Effectiveness of the CoronaVac vaccine in older adults during a gamma variant associated epidemic of covid-19 in Brazil: test negative case-control study

COVID-19 vaccine updates for people under different conditions

SARS-CoV-2 has caused global waves of infection since December 2019 and continues to persist today. The emergence of SARS-CoV-2 variants with strong immune evasion capabilities has compromised the effectiveness of existing vaccines against breakthrough infections. Therefore, it is important to determine the best utilization strategies for different demographic groups given the variety of vaccine options available. In this review, we will discuss the protective efficacy of vaccines during different stages of the epidemic and emphasize the importance of timely updates to target prevalent variants, which can significantly improve immune protection. While it is recognized that vaccine effectiveness may be lower in certain populations such as the elderly, individuals with chronic comorbidities (e.g., diabetes with poor blood glucose control, those on maintenance dialysis), or those who are immunocompromised compared to the general population, administering multiple doses can result in a strong protective immune response that outweighs potential risks. However, caution should be exercised when considering vaccines that might trigger an intense immune response in populations prone to inflammatory flare or other complications. In conclusion, individuals with special conditions require enhanced and more effective immunization strategies to prevent infection or reinfection, as well as to avoid the potential development of long COVID.

Estimated Deaths Averted in Adults by COVID-19 Vaccination in Select Latin American and Caribbean Countries

Background

The coronavirus disease 2019 (COVID-19) pandemic has had a significant impact on global health, with millions of lives lost worldwide. Vaccination has emerged as a crucial strategy in mitigating the impact of the disease. This study aims to estimate the number of deaths averted through vaccination in Latin America and the Caribbean region (LAC) during the first year and a half of vaccination rollout (January 2021-May 2022).

Methods

Publicly available data on COVID-19 deaths and vaccination rates were used to estimate the total number of deaths averted via vaccination in LAC. Using estimates for number of deaths, number of vaccinated, and vaccine effectiveness, a counterfactual estimated number of deaths observed without vaccination was calculated. Vaccine effectiveness estimates were obtained from published studies. The analysis focused on 17 countries in LAC and considered adults aged 18 years and older.

Results

After accounting for underreporting, the analysis estimated that >1.49 million deaths were caused by COVID-19 in the selected countries during the study period. Without vaccination, the model estimated that between 2.10 and 4.11 million COVID-19 deaths would have occurred. Consequently, vaccination efforts resulted in ∼610 000 to 2.61 million deaths averted.

Conclusions

This study represents the first large-scale, multicenter estimate of population-level vaccine impact on COVID-19 mortality in LAC. The findings underscore the substantial impact of timely and widespread vaccination in averting COVID-19 deaths. These results provide crucial support for vaccination programs aimed at combating epidemic infectious diseases in the region and future pandemics.

Real-world effectiveness of the CoronaVac vaccine in a retrospective population-based cohort in four Colombian cities (2021-2022)

OBJECTIVES

The National Vaccination Plan against SARS-CoV-2/COVID-19 was launched by the Ministry of Health and Social Protection on 14 February 2021. The main objective of this study was to evaluate the effectiveness of the CoronaVac in preventing the three clinical outcomes of infection, hospitalisation, or death, in a real-world scenario.

DESIGN

This was a population-based retrospective dynamic cohort study using a multivariate Cox model to calculate hazard ratios to estimate vaccine effectiveness from 17 February 2021 to 30 June 2022. The data were collected from surveillance systems for 12 months for each individual. Four cities were selected on the basis of the reliability of their data bases.

RESULTS

The rates of CoronaVac effectiveness were 32% (95% confidence interval [CI] 31-33) for preventing infection, 55% (95% CI 54-56) for hospitalisation, and 90% (95% CI 89-90) for death, at the end of follow-up. These findings were more consistent during the first 4 months. Compared with the unvaccinated group, homologous booster doses appeared to increase effectiveness in preventing hospitalisation, whereas heterologous booster doses increased protection for both hospitalisation and death. Booster doses did not improve effectiveness among those already vaccinated with CoronaVac, even when they received heterologous boosters.

CONCLUSIONS

CoronaVac demonstrated effectiveness in preventing death and hospitalisation during the first year of follow-up, but its effectiveness in preventing infection was lower, decreasing rapidly after the first 4 months of follow-up. The effectiveness was higher among children aged between 3 and 12 years, and among adults aged ≥60 years. Booster doses did not improve effectiveness among those already vaccinated with CoronaVac.

COVID-19 vaccine coverage effectiveness among elderly with geographical information system mapping: what about Indonesia?

Background

The elderly are the next priority after health workers and public service workers get the COVID-19 vaccine to control morbidity and even mortality in the elderly who have a risk factor that is up to 60 times more severe than children.

Objectives

This study aimed to spatially analyze the effectiveness of COVID-19 vaccine coverage among the elderly in Indonesia with geographic information system (GIS) mapping and to analyze the relationship between COVID-19 vaccine coverage in the elderly with the COVID-19 cure rate.

Design

This quantitative study used secondary data on COVID-19 vaccination coverage in the elderly group of Central Java Province, Indonesia in 2021.

Methods

Data were analyzed using a simple linear correlation test to test the relationship between variables with a 1,774,396 elderly sample size, then distributed using mapping of COVID-19 vaccination coverage using a GIS.

Results

The relationship between COVID-19 vaccine dose-2 elderly coverage cure rate showed a strong relationship (r = 0.677) and a positive pattern. The coefficient value with a determination of 0.459 means that the regression line equation obtained can explain 45.90% of the variation in the COVID-19 cure rate. There was a significant relationship between COVID-19 vaccine elderly coverage and the COVID-19 cure rate (p-value = 0.005).

Conclusion

Clinicians and public health workers should continue to encourage elderly vaccination at all recommended doses for eligible individuals.

COVID-19 inpatient care performance in the unified health system, São Paulo state, Brazil: an application of standardized mortality ratio for hospitals' comparisons : COVID-19 inpatient care performance in SUS, Brazil

OBJECTIVE

To evaluate the variation in COVID-19 inpatient care mortality among hospitals reimbursed by the Unified Health System (SUS) in the first two years of the pandemic in São Paulo state and make performance comparisons within periods and over time.

METHODS

Observational study based on secondary data from the Hospital Information System. The study universe consisted of 289,005 adult hospitalizations whose primary diagnosis was COVID-19 in five periods from 2020 to 2022. A multilevel regression model was applied, and the death predictive variables were sex, age, Charlson Index, obesity, type of admission, Brazilian Deprivation Index (BrazDep), the month of admission, and hospital size. Then, the total observed deaths and total deaths predicted by the model's fixed effect component were aggregated by each hospital, estimating the Standardized Mortality Ratio (SMR) in each period. Funnel plots with limits of two standard deviations were employed to classify hospitals by performance (higher-than-expected, as expected, and lower-than-expected) and determine whether there was a change in category over the periods.

RESULTS

A positive association was observed between hospital mortality and size (number of beds). There was greater variation in the percentage of hospitals with as-expected performance (39.5 to 76.1%) and those with lower-than-expected performance (6.6 to 32.3%). The hospitals with higher-than-expected performance remained at around 30% of the total, except in the fifth period. In the first period, 64 hospitals (18.3%) had lower-than-expected performance, with standardized mortality ratios ranging from 1.2 to 4.4, while in the last period, only 23 (6.6%) hospitals were similarly classified, with ratios ranging from 1.3 to 2.8. A trend of homogenization and adjustment to expected performance was observed over time.

CONCLUSION

Despite the study's limitations, the results suggest an improvement in the COVID-19 inpatient care performance of hospitals reimbursed by the SUS in São Paulo over the period studied, measured by the standardized mortality ratio for hospitalizations due to COVID-19. Moreover, the methodological approach adapted to the Brazilian context provides an applicable tool to follow-up hospital's performance in caring all or specific-cause hospitalizations, in regular or exceptional emergency situations.

Effectiveness of CoronaVac in the prevention of COVID-19, a test-negative case-control study in Brazil

The present study aimed to evaluate the effectiveness of two doses of CoronaVac in preventing SARS-CoV-2 symptomatic disease with virological confirmation, as well as in the prevention of COVID-19 moderate and severe cases. A test-negative unmatched case-control design was used, in which cases were patients with suspected COVID-19 (presenting at least two of the following symptoms: fever, chills, sore throat, headache, cough, runny nose, olfactory or taste disorders) with virological confirmation, and controls were those whose SARS-CoV-2 test was negative. As for exposure, participants were classified as unvaccinated, or vaccinated with a complete schedule. Suspected COVID-19 cases were identified from March to November 2021, in two cities located in the State of São Paulo, Brazil. All participants signed the Informed Consent Form before enrollment. RT-PCR results and vaccination data were obtained from the local surveillance systems. Up to two phone calls were made to obtain information on the outcome of the cases. A total of 2981 potential participants were screened for eligibility, of which 2163 were included, being 493 cases and 1670 controls. Vaccination, age, the reported contact with a COVID-19 suspected or confirmed case in the 14 days before symptoms onset, and the educational level were the variables independently associated with the outcome. The adjusted vaccine effectiveness for symptomatic COVID-19 (AVE) was 39.0 % (95 % CI 6.0-60.0 %). The AVE in the prevention of moderate and severe disease was 91.0 % (95 % CI 76.0-97.0 %). Our results were influenced by the waning of the Gamma variant, in the second trimester of 2021, followed by the increase in vaccination coverage, and a drop in the number of cases in the second half of the year. The study demonstrated the high effectiveness of CoronaVac in preventing moderate/severe COVID-19 cases.

Impacts of COVID-19 vaccine boosters on clinical outcomes associated with the Omicron variant in China: A cross-sectional survey

Objective

To investigate the real-world effectiveness of COVID-19 vaccine boosters during China's Omicron wave.

Methods

In January 2023, we surveyed Shenzhen, China residents via online questionnaires to investigate their COVID-19 symptoms and vaccination history. The outcomes of interest included fever, other COVID-19-related symptoms, severity of symptoms, whether early onset (before December 23, 2022) and duration. Respondents were categorized as no booster, one booster 6mo ago, one booster within 6mo, or two boosters based on dose count and vaccination timing. We used multivariable logistic regressions and Tobit models to assess COVID-19 vaccine booster impacts.

Results

Compared to the no booster group, two booster recipients had a lower fever risk (OR = 0.35, 95 %CI = 0.16-0.76) but not lower risks of COVID-19-related symptoms (OR = 0.74, 95 %CI = 0.26-2.06) and self-reported severe symptoms (OR = 0.47, 95 %CI = 0.19-1.15). Nor did the two booster recipients had a shorter illness duration (marginal effect = -0.79 days, 95 %CI = -1.65-0.07) and a lower risk of symptom onset delay (OR = 0.48, 95 %CI = 0.19-1.23). Compared to the no booster group, both one booster within six months (OR = 2.17, 95 %CI = 1.34-3.52) and one booster six months ago (OR = 1.30, 95 %CI = 0.92-1.82) did not reduce the risks of fever and symptoms (one booster within six months: OR = 1.57, 95 %CI = 0.84-2.90; one booster six months ago: OR = 1.23, 95 %CI = 0.79-1.93). Regardless of timing, one booster did not reduce illness duration (within six months: marginal effect = 0.25 days, 95 %CI = -0.20-0.70; six months ago: marginal effect = 0.27 days, 95 %CI = -0.08-0.62). However, receiving one booster within six months delayed symptom onset (OR = 0.54, 95 %CI = 0.34-0.86), while one booster six months ago did not (OR = 1.03, 95 %CI = 0.74-1.44).

Conclusions

Receiving two booster doses reduced the onset of fever during the Omicron outbreak in mainland China.

The landscape of the COVID-19 pandemic in Poland emerging from epidemiological and genomic data

The COVID-19 pandemic has profoundly affected all aspects of our lives. Through real-time monitoring and rapid vaccine implementation, we succeeded in suppressing the spread of the disease and mitigating its consequences. Finally, conclusions can be summarized and drawn. Here, we use the example of Poland, which was seriously affected by the pandemic. Compared to other countries, Poland has not achieved impressive results in either testing or vaccination, which may explain its high mortality (case fatality rate, CFR 1.94%). Through retrospective analysis of data collected by the COVID-19 Data Portal Poland, we found significant regional differences in the number of tests performed, number of cases detected, number of COVID-19-related deaths, and vaccination rates. The Masovian, Greater Poland, and Pomeranian voivodeships, the country's leaders in vaccination, reported high case numbers but low death rates. In contrast, the voivodeships in the eastern and southern parts of Poland (Subcarpathian, Podlaskie, Lublin, Opole), which documented low vaccination levels and low case numbers, had higher COVID-19-related mortality rates. The strong negative correlation between the CFR and the percentage of the population that was vaccinated in Poland supports the validity of vaccination. To gain insight into virus evolution, we sequenced more than 500 genomes and analyzed nearly 80 thousand SARS-CoV-2 genome sequences deposited in GISAID by Polish diagnostic centers. We showed that the SARS-CoV-2 variant distribution over time in Poland reflected that in Europe. Haplotype network analysis allowed us to follow the virus transmission routes and identify potential superspreaders in each pandemic wave.

Adjuvants for cancer mRNA vaccines in the era of nanotechnology: strategies, applications, and future directions

Research into mRNA vaccines is advancing rapidly, with proven efficacy against coronavirus disease 2019 and promising therapeutic potential against a variety of solid tumors. Adjuvants, critical components of mRNA vaccines, significantly enhance vaccine effectiveness and are integral to numerous mRNA vaccine formulations. However, the development and selection of adjuvant platforms are still in their nascent stages, and the mechanisms of many adjuvants remain poorly understood. Additionally, the immunostimulatory capabilities of certain novel drug delivery systems (DDS) challenge the traditional definition of adjuvants, suggesting that a revision of this concept is necessary. This review offers a comprehensive exploration of the mechanisms and applications of adjuvants and self-adjuvant DDS. It thoroughly addresses existing issues mentioned above and details three main challenges of immune-related adverse event, unclear mechanisms, and unsatisfactory outcomes in old age group in the design and practical application of cancer mRNA vaccine adjuvants. Ultimately, this review proposes three optimization strategies which consists of exploring the mechanisms of adjuvant, optimizing DDS, and improving route of administration to improve effectiveness and application of adjuvants and self-adjuvant DDS.

Effectiveness of the fourth dose of COVID-19 vaccines against severe COVID-19 among adults 40 years or older in Brazil: a population-based cohort study

Background

The emergence of COVID-19 variants with immune scape and the waning of primary vaccine schemes effectiveness have prompted many countries to indicate first and second booster COVID-19 vaccine doses to prevent severe COVID-19. However, current available evidence on second booster dose effectiveness are mostly limited to high-income countries, older adults, and mRNA-based vaccination schemes scenarios. We aimed to investigate the relative vaccine effectiveness (rVE) of the fourth dose compared to three doses for severe COVID-19 outcomes in Brazil; and compare the rVE of a fourth dose with an mRNA vaccine compared to adenovirus-based product in the same settings.

Methods

We performed a target emulated trial using a population-based cohort of individuals aged 40 years or older who have received a homologous primary scheme of CoronaVac, ChAdOx1, or BNT162b2, and any third dose product and were eligible for the fourth dose in Brazil. The primary outcome was COVID-19 associated hospitalization or death. We built Cohort A matching individuals vaccinated with a fourth dose to individuals who received three doses to estimate the rVE of the fourth dose. We built Cohort B, a subset of Cohort A, matching mRNA-based (mRNA) to adenovirus-based fourth dose vaccinated individuals to compare their relative hazards for severe COVID-19.

Findings

46,693,484 individuals were included in Cohort A and 6,763,016 in Cohort B. 45% of them were aged between 40 and 60 years old, and 48% between 60 and 79 years old. In Cohort A, the most common previous series was a ChAdOx1 two-dose followed by BNT162b2 (44%), and a CoronaVac two-dose followed by a BNT162b2 (36%). Among those fourth dose vaccinated, 36.9% received ChAdOx1, 32.7% Ad26.COV2.S, 25.8% BNT162b2, and 4.7% CoronaVac. In Cohort B, among those who received an adenovirus fourth dose, 53.7% received ChAdOx1 and 46.3% received Ad26.COV2.S. The estimated rVE for the primary outcome of four doses compared to three doses was 44.1% (95% CI 42.3-46.0), with some waning during follow-up (rVE 7-60 days 46.8% [95% CI 44.4-49.1], rVE after 120 days 33.8% [95% CI 18.0-46.6]). Among fourth dose vaccinated individuals, mRNA-based vaccinated individuals had lower hazards for hospitalization or death compared to adenovirus-vaccinated individuals (HR 0.81, 95% CI 0.75-0.87). After 120 days, no difference in hazards between groups was observed (HR 1.35, 95% CI 0.93-1.97). Similar findings were observed for hospitalization and death separately, except no evidence for differences between fourth dose brands for death in Cohort B.

Interpretation

In a heterogeneous scenario of primary and first booster vaccination combinations, a fourth dose provided meaningful and durable protection against severe COVID-19 outcomes. Compared to adenovirus-based booster, a fourth dose wild-type mRNA vaccine was associated with immediate lower hazards of hospitalization or death unsustained after 120 days.

Funding

None.

Homologous and Heterologous Covid-19 Booster Vaccinations Against SARS-CoV-2 Infection in the Elderly

A third booster doses for the 2019 coronavirus disease (COVID-19) is widely used all over the world, especially in risky individuals, with the recommendation of WHO. The purpose of this study was to evaluate the effectiveness of mRNA (BNT162b2), and CoronaVac (Sinovac Biotech) vaccines as a reminder dose following two doses of CoronaVac against COVID-19 infection, serious illness, and mortality in the geriatric population aged 75 and older during the delta variant dominant period. Our study comprised 2730 individuals the age of 75 and older in total, of which 1082 (39.6%) were male and 1648 (60.4%) were female. The vaccine effectiveness (VE) of 2 doses of CoronaVac + 1 dose of BNT162b2 vaccine combination against COVID-19 was determined as 89.2% (95% Confidence interval (CI) 80.7-93.9%), while the VE of 3 doses of CoronaVac vaccine was determined as 80.4% (95% CI 60.5-90.2%). Geriatric patients who received three doses of CoronaVac vaccine did not need intensive care. No deaths were observed in the vaccinated groups. While the VE of vaccination with 2 doses of CoronaVac + 1 dose of BNT162b2 was 41.8% (95% CI 0-74.1%) against hospitalization, 64.4% (95% CI 0-94.7%) against intensive care unit admission, the VE of vaccination with three doses of the CoronaVac was 78.2% (95% CI 0-96.5%) against hospitalization. In conclusion, our research showed that, even with the emergence of viral variants, a third dose of the CoronaVac and BNT162b2 vaccines is highly effective against symptomatic SARS-CoV-2 infection. Third-dose vaccination regimens, including heterologous and homologous vaccines, can be an effective tool in controlling the COVID-19 pandemic and the emergence of new variants.

Lessons we learned during the past four challenging years in the COVID-19 era: pharmacotherapy, long COVID complications, and vaccine development

About four years have passed since the detection of the first cases of COVID-19 in China. During this lethal pandemic, millions of people have lost their lives around the world. Since the first waves of COVID-19 infection, various pharmacotherapeutic agents have been examined in the management of COVID-19. Despite all these efforts in pharmacotherapy, drug repurposing, and design and development of new drugs, multiple organ involvement and various complications occurred during COVID-19. Some of these complications became chronic and long-lasting which led to the "long COVID" syndrome appearance. Therefore, the best way to eradicate this pandemic is prophylaxis through mass vaccination. In this regard, various vaccine platforms including inactivated vaccines, nucleic acid-based vaccines (mRNA and DNA vaccines), adenovirus-vectored vaccines, and protein-based subunit vaccines have been designed and developed to prevent or reduce COVID-19 infection, hospitalization, and mortality rates. In this focused review, at first, the most commonly reported clinical presentations of COVID-19 during these four years have been summarized. In addition, different therapeutic regimens and their latest status in COVID-19 management have been listed. Furthermore, the "long COVID" and related signs, symptoms, and complications have been mentioned. At the end, the effectiveness of available COVID-19 vaccines with different platforms against early SARS-CoV-2 variants and currently circulating variants of interest (VOI) and the necessity of booster vaccine shots have been summarized and discussed in more detail.

Immune Response to an Inactivated Vaccine of SARS-CoV-2 (CoronaVac) in an Indigenous Brazilian Population: A Cohort Study

INTRODUCTION

Although the adaptive immune responses to the CoronaVac vaccine are known, their dynamics in indigenous communities remain unclear. In this study, we assessed the humoral and cellular immune responses to CoronaVac (Sinovac Biotech Life Sciences, 2021 NCT05225285, Beijing, China), in immunized Brazilian indigenous individuals.

METHODS

We conducted a prospective cohort study on indigenous Brazilian people between February 2021 and June 2021. Analyses of immune responses were carried out before (T1) and after a vaccination schedule was completed (T2). Demographic data were collected using a questionnaire.

RESULTS

We initially included 328 patients; among them, 120 (36.6%) had no SARS-CoV-2 antibodies. Peripheral blood mononuclear cells (PBMCs) were collected from 106 patients during follow-up visits, of which 91 samples were analyzed by immunophenotyping assay to detect SARS-CoV-2-specific memory T-cell response. Post-vaccination, the levels of memory B-cells and Natural Killer T-lymphocytes increased. Bororó village residents, females, and Terena ethnic group members had higher levels of anti-spike IgG antibodies post-vaccination, whereas alcohol and tobacco users had lower concentrations.

CONCLUSIONS

To our best knowledge, this was the first comprehensive assessment of antibody and T-cell responses against CoronaVac vaccination in indigenous patients. Our findings showed that antibody response and T-cell immunity against SARS-CoV-2 were present in most patients following the vaccination schedule.

Immunogenicity and efficacy of VLA2001 vaccine against SARS-CoV-2 infection in male cynomolgus macaques

BACKGROUND

The fight against COVID-19 requires mass vaccination strategies, and vaccines inducing durable cross-protective responses are still needed. Inactivated vaccines have proven lasting efficacy against many pathogens and good safety records. They contain multiple protein antigens that may improve response breadth and can be easily adapted every year to maintain preparedness for future seasonally emerging variants.

METHODS

The vaccine dose was determined using ELISA and pseudoviral particle-based neutralization assay in the mice. The immunogenicity was assessed in the non-human primates with multiplex ELISA, neutralization assays, ELISpot and intracellular staining. The efficacy was demonstrated by viral quantification in fluids using RT-qPCR and respiratory tissue lesions evaluation.

RESULTS

Here we report the immunogenicity and efficacy of VLA2001 in animal models. VLA2001 formulated with alum and the TLR9 agonist CpG 1018™ adjuvant generate a Th1-biased immune response and serum neutralizing antibodies in female BALB/c mice. In male cynomolgus macaques, two injections of VLA2001 are sufficient to induce specific and polyfunctional CD4+ T cell responses, predominantly Th1-biased, and high levels of antibodies neutralizing SARS-CoV-2 infection in cell culture. These antibodies also inhibit the binding of the Spike protein to human ACE2 receptor of several variants of concern most resistant to neutralization. After exposure to a high dose of homologous SARS-CoV-2, vaccinated groups exhibit significant levels of protection from viral replication in the upper and lower respiratory tracts and from lung tissue inflammation.

CONCLUSIONS

We demonstrate that the VLA2001 adjuvanted vaccine is immunogenic both in mouse and NHP models and prevent cynomolgus macaques from the viruses responsible of COVID-19.

What makes SARS-CoV-2 unique? Focusing on the spike protein

Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) seriously threatens public health and safety. Genetic variants determine the expression of SARS-CoV-2 structural proteins, which are associated with enhanced transmissibility, enhanced virulence, and immune escape. Vaccination is encouraged as a public health intervention, and different types of vaccines are used worldwide. However, new variants continue to emerge, especially the Omicron complex, and the neutralizing antibody responses are diminished significantly. In this review, we outlined the uniqueness of SARS-CoV-2 from three perspectives. First, we described the detailed structure of the spike (S) protein, which is highly susceptible to mutations and contributes to the distinct infection cycle of the virus. Second, we systematically summarized the immunoglobulin G epitopes of SARS-CoV-2 and highlighted the central role of the nonconserved regions of the S protein in adaptive immune escape. Third, we provided an overview of the vaccines targeting the S protein and discussed the impact of the nonconserved regions on vaccine effectiveness. The characterization and identification of the structure and genomic organization of SARS-CoV-2 will help elucidate its mechanisms of viral mutation and infection and provide a basis for the selection of optimal treatments. The leaps in advancements regarding improved diagnosis, targeted vaccines and therapeutic remedies provide sound evidence showing that scientific understanding, research, and technology evolved at the pace of the pandemic.

Waning immune response to CoronaVac in health care workers from different age groups

Introduction

The waning of serum antibodies against severe acute respiratory syndrome coronavirus 2 observed in several studies raises questions about long-term immunity. Lower antibody levels are associated with new cases of COVID-19 even postvaccination, leading to the administration of booster doses.

Objectives

To evaluate the postvaccination immune humoral response and the relationship between postvaccination seropositivity rates and demographic data among health care workers 6 months after CoronaVac vaccination.

Methods

This was a cross-sectional study including health care workers vaccinated with two doses of CoronaVac after 6 months or more. The present study was conducted with the analysis of postvaccination serology test to assess the level of humoral response (anti-receptor binding domain IgG) after vaccination.

Results

A total of 325 participants were enrolled, of whom 76% were female, with a median age of 42 years (20-85; interquartile range 31-53). Overall, 18.8% (61) of the participants results were seropositive for anti-receptor binding domain IgG; 81.2% did not have sufficient quantitative titers. The IgG titers obtained from female health care workers did not differ from those obtained from seropositive male health care workers, regardless of age.

Conclusions

A group of positive quantitative titers was identified in the serology test for IgG antibodies against severe acute respiratory syndrome coronavirus 2. Further studies are needed to determine the durability of postvaccination antibodies and how serology testing can be used to determine the ideal timing for booster doses of the vaccine.

The Association Between Prepandemic ICU Performance and Mortality Variation in COVID-19: A Multicenter Cohort Study of 35,619 Critically Ill Patients

BACKGROUND

During the COVID-19 pandemic, ICUs remained under stress and observed elevated mortality rates and high variations of outcomes. A knowledge gap exists regarding whether an ICU performing best during nonpandemic times would still perform better when under high pressure compared with the least performing ICUs.

RESEARCH QUESTION

Does prepandemic ICU performance explain the risk-adjusted mortality variability for critically ill patients with COVID-19?

STUDY DESIGN AND METHODS

This study examined a cohort of adults with real-time polymerase chain reaction-confirmed COVID-19 admitted to 156 ICUs in 35 hospitals from February 16, 2020, through December 31, 2021, in Brazil. We evaluated crude and adjusted in-hospital mortality variability of patients with COVID-19 in the ICU during the pandemic. Association of baseline (prepandemic) ICU performance and in-hospital mortality was examined using a variable life-adjusted display (VLAD) during the pandemic and a multivariable mixed regression model adjusted by clinical characteristics, interaction of performance with the year of admission, and mechanical ventilation at admission.

RESULTS

Thirty-five thousand six hundred nineteen patients with confirmed COVID-19 were evaluated. The median age was 52 years, median Simplified Acute Physiology Score 3 was 42, and 18% underwent invasive mechanical ventilation. In-hospital mortality was 13% and 54% for those receiving invasive mechanical ventilation. Adjusted in-hospital mortality ranged from 3.6% to 63.2%. VLAD in the most efficient ICUs was higher than the overall median in 18% of weeks, whereas VLAD was 62% and 84% in the underachieving and least efficient groups, respectively. The least efficient baseline ICU performance group was associated independently with increased mortality (OR, 2.30; 95% CI, 1.45-3.62) after adjusting for patient characteristics, disease severity, and pandemic surge.

INTERPRETATION

ICUs caring for patients with COVID-19 presented substantial variation in risk-adjusted mortality. ICUs with better baseline (prepandemic) performance showed reduced mortality and less variability. Our findings suggest that achieving ICU efficiency by targeting improvement in organizational aspects of ICUs may impact outcomes, and therefore should be a part of the preparedness for future pandemics.

Alterations in microbiota of patients with COVID-19: implications for therapeutic interventions

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) recently caused a global pandemic, resulting in more than 702 million people being infected and over 6.9 million deaths. Patients with coronavirus disease (COVID-19) may suffer from diarrhea, sleep disorders, depression, and even cognitive impairment, which is associated with long COVID during recovery. However, there remains no consensus on effective treatment methods. Studies have found that patients with COVID-19 have alterations in microbiota and their metabolites, particularly in the gut, which may be involved in the regulation of immune responses. Consumption of probiotics may alleviate the discomfort caused by inflammation and oxidative stress. However, the pathophysiological process underlying the alleviation of COVID-19-related symptoms and complications by targeting the microbiota remains unclear. In the current study, we summarize the latest research and evidence on the COVID-19 pandemic, together with symptoms of SARS-CoV-2 and vaccine use, with a focus on the relationship between microbiota alterations and COVID-19-related symptoms and vaccine use. This work provides evidence that probiotic-based interventions may improve COVID-19 symptoms by regulating gut microbiota and systemic immunity. Probiotics may also be used as adjuvants to improve vaccine efficacy.

Revolutionizing Cancer Treatment: Unleashing the Power of Viral Vaccines, Monoclonal Antibodies, and Proteolysis-Targeting Chimeras in the New Era of Immunotherapy

In the realm of cancer immunotherapy, a profound evolution has ushered in sophisticated strategies that encompass both traditional cancer vaccines and emerging viral vaccines. This comprehensive Review offers an in-depth exploration of the methodologies, clinical applications, success stories, and future prospects of these approaches. Traditional cancer vaccines have undergone significant advancements utilizing diverse modalities such as proteins, peptides, and dendritic cells. More recent innovations have focused on the physiological mechanisms enabling the human body to recognize and combat precancerous and malignant cells, introducing specific markers like peptide-based anticancer vaccines targeting tumor-associated antigens. Moreover, cancer viral vaccines, leveraging engineered viruses to stimulate immune responses against specific antigens, exhibit substantial promise in inducing robust and enduring immunity. Integration with complementary therapeutic methods, including monoclonal antibodies, adjuvants, and radiation therapy, has not only improved survival rates but also deepened our understanding of viral virulence. Recent strides in vaccine design, encompassing oncolytic viruses, virus-like particles, and viral vectors, mark the frontier of innovation. While these advances hold immense potential, critical challenges must be addressed, such as strategies for immune evasion, potential off-target effects, and the optimization of viral genomes. In the landscape of immunotherapy, noteworthy innovations take the spotlight from the use of immunomodulatory agents for the enhancement of innate and adaptive immune collaboration. The emergence of proteolysis-targeting chimeras (PROTACs) as precision tools for cancer therapy is particularly exciting. With a focus on various cancers, from melanoma to formidable solid tumors, this Review critically assesses types of cancer vaccines, mechanisms, barriers in vaccine therapy, vaccine efficacy, safety profiles, and immune-related adverse events, providing a nuanced perspective on the underlying mechanisms involving cytotoxic T cells, natural killer cells, and dendritic cells. The Review also underscores the transformative potential of cutting-edge technologies such as clinical studies, molecular sequencing, and artificial intelligence in advancing the field of cancer vaccines. These tools not only expedite progress but also emphasize the multidimensional and rapidly evolving nature of this research, affirming its profound significance in the broader context of cancer therapy.

Test negative design for vaccine effectiveness estimation in the context of the COVID-19 pandemic: A systematic methodology review

BACKGROUND

During the height of the global COVID-19 pandemic, the test-negative design (TND) was extensively used in many countries to evaluate COVID-19 vaccine effectiveness (VE). Typically, the TND involves the recruitment of care-seeking individuals who meet a common clinical case definition. All participants are then tested for an infection of interest.

OBJECTIVES

To review and describe the variation in TND methodology, and disclosure of potential biases, as applied to the evaluation of COVID-19 VE during the early vaccination phase of the pandemic.

METHODS

We conducted a systematic review by searching four biomedical databases using defined keywords to identify peer-reviewed articles published between January 1, 2020, and January 25, 2022. We included only original articles that employed a TND to estimate VE of COVID-19 vaccines in which cases and controls were evaluated based on SARS-CoV-2 laboratory test results.

RESULTS

We identified 96 studies, 35 of which met the defined criteria. Most studies were from North America (16 studies) and targeted the general population (28 studies). Outcome case definitions were based primarily on COVID-19-like symptoms; however, several papers did not consider or specify symptoms. Cases and controls had the same inclusion criteria in only half of the studies. Most studies relied upon administrative or hospital databases assembled for a different (non-evaluation) clinical purpose. Potential unmeasured confounding (20 studies), misclassification of current SARS-CoV-2 infection (16 studies) and selection bias (10 studies) were disclosed as limitations by some studies.

CONCLUSION

We observed potentially meaningful deviations from the validated design in the application of the TND during the COVID-19 pandemic.

Immunomodulatory Peptides as Vaccine Adjuvants and Antimicrobial Agents

The underdevelopment of adjuvant discovery and diversity, compared to core vaccine technology, is evident. On the other hand, antibiotic resistance is on the list of the top ten threats to global health. Immunomodulatory peptides that target a pathogen and modulate the immune system simultaneously are promising for the development of preventive and therapeutic molecules. Since investigating innate immunity in insects has led to prominent achievements in human immunology, such as toll-like receptor (TLR) discovery, we used the capacity of the immunomodulatory peptides of arthropods with concomitant antimicrobial or antitumor activity. An SVM-based machine learning classifier identified short immunomodulatory sequences encrypted in 643 antimicrobial peptides from 55 foe-to-friend arthropods. The critical features involved in efficacy and safety were calculated. Finally, 76 safe immunomodulators were identified. Then, molecular docking and simulation studies defined the target of the most optimal peptide ligands among all human cell-surface TLRs. SPalf2-453 from a crab is a cell-penetrating immunoadjuvant with antiviral properties. The peptide interacts with the TLR1/2 heterodimer. SBsib-711 from a blackfly is a TLR4/MD2 ligand used as a cancer vaccine immunoadjuvant. In addition, SBsib-711 binds CD47 and PD-L1 on tumor cells, which is applicable in cancer immunotherapy as a checkpoint inhibitor. MRh4-679 from a shrimp is a broad-spectrum or universal immunoadjuvant with a putative Th1/Th2-balanced response. We also implemented a pathway enrichment analysis to define fingerprints or immunological signatures for further in vitro and in vivo immunogenicity and reactogenicity measurements. Conclusively, combinatorial machine learning, molecular docking, and simulation studies, as well as systems biology, open a new opportunity for the discovery and development of multifunctional prophylactic and therapeutic lead peptides.

SARS-CoV-2 vaccines in China could reduce COVID-19-related respiratory syndromes and deaths: A retrospective cohort study

Background

Information is limited regarding the effectiveness of the inactivated vaccine for COVID-19 approved in China in preventing infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) when administered in real-world conditions.

Methods

We retrospectively surveyed 1352 patients with a positive SARS-CoV-2 nucleic acid test treated at a major tertiary medical center in Foshan city (Guangdong, China) between November 2022 and February 2023. The exposure group was patients who had previously received the COVID-19 vaccine, which included patients who had received different doses of the vaccine and different vaccine types. The primary outcome of this study was the effectiveness of the vaccine in preventing severe disease and death among SARS-CoV-2-infected patients.

Results

We found a mortality rate of 12.1 % associated with COVID-19. The results showed that an increase in the number of vaccine doses was associated with a reduction in in-hospital mortality. When compared to unvaccinated patients, vaccinated patients had an 8.5 % lower mortality rate. There was also a statistically significant reduction in the risk of death among vaccinated patients compared to unvaccinated patients (OR = 0.521 [95 % CI, 0.366 to 0.741]). Patients who had received the vaccine had a 22.8 % reduction in the risk of severe disease. In addition, the use of antiviral drugs decreased progressively with increasing vaccine doses (P < 0.05). Of these, anticoagulation, Paxlovid, and mechanical ventilation were used least frequently in the one-dose group.

Conclusions

The vaccines approved in China mitigated the incidence of severe COVID-19 and reduced mortality. These findings suggest that COVID-19 vaccination can help to control the pandemic.

Temporary impact on medical system and effectiveness of mitigation strategies after COVID-19 policy adjustment in China: a modeling study

Background

As China amends its "zero COVID" strategy, a sudden increase in the number of infections may overwhelm medical resources and its impact has not been quantified. Specific mitigation strategies are needed to minimize disruption to the healthcare system and to prepare for the next possible epidemic in advance.

Method

We develop a stochastic compartmental model to project the burden on the medical system (that is, the number of fever clinic visits and admission beds) of China after adjustment to COVID-19 policy, which considers the epidemiological characteristics of the Omicron variant, age composition of the population, and vaccine effectiveness against infection and severe COVD-19. We also estimate the effect of four-dose vaccinations (heterologous and homologous), antipyretic drug supply, non-pharmacological interventions (NPIs), and triage treatment on mitigating the domestic infection peak.

Result

As to the impact on the medical system, this epidemic is projected to result in 398.02 million fever clinic visits and 16.58 million hospitalizations, and the disruption period on the healthcare system is 18 and 30 days, respectively. Antipyretic drug supply and booster vaccination could reduce the burden on emergency visits and hospitalization, respectively, while neither of them could not reduce to the current capacity. The synergy of several different strategies suggests that increasing the heterologous booster vaccination rate for older adult to over 90% is a key measure to alleviate the bed burden for respiratory diseases on the basis of expanded healthcare resource allocation.

Conclusion

The Omicron epidemic followed the adjustment to COVID-19 policy overloading many local health systems across the country at the end of 2022. The combined effect of vaccination, antipyretic drug supply, triage treatment, and PHSMs could prevent overwhelming medical resources.

COVID-19 inpatient mortality in Brazil from 2020 to 2022: a cross-sectional overview study based on secondary data

BACKGROUND

In Brazil, the COVID-19 pandemic found the universal and public Unified Health System (SUS) with problems accumulated over time, due, among other reasons, to low investments, and disparities in resource distribution. The preparedness and response of the healthcare system, involving the SUS and a private sector, was affected by large socioeconomic and healthcare access inequities. This work was aimed at offering an overview of COVID-19 inpatient mortality during the pandemic in Brazil, exploring factors associated with its variations and, specifically, differences across public, private (for-profit) and philanthropic (private non-profit) inpatient healthcare units, providers, and non-providers of services to the SUS.

METHODS

This cross-sectional study used public secondary data. The main data source was the SIVEP-Gripe, which comprises data on severe acute respiratory illness records prospectively collected. We also employed the National Record of Health Establishments, the SUS' Hospitalization Information System and municipalities' data from IBGE. We considered adult COVID-19 hospitalizations registered in SIVEP-Gripe from February 2020 to December 2022 in inpatient healthcare units with a minimum of 100 cases in the period. Data analyses explored the occurrence of inpatient mortality, employing general linear mixed models to identify the effects of patients', health care processes', healthcare units' and municipalities' characteristics on it.

RESULTS

About 70% of the COVID-19 hospitalizations in Brazil were covered by the SUS, which attended the more vulnerable population groups and had worse inpatient mortality. In general, non-SUS private and philanthropic hospitals, mostly reimbursed by healthcare insurance plans accessible for more privileged socioeconomic classes, presented the best outcomes. Southern Brazil had the best performance among the macro-regions. Black and indigenous individuals, residents of lower HDI municipalities, and those hospitalized out of their residence city presented higher odds of inpatient mortality. Moreover, adjusted inpatient mortality rates were higher in the pandemic peak moments and were significantly reduced after COVID-19 vaccination reaching a reasonable coverage, from July 2021.

CONCLUSIONS

COVID-19 exposed socioeconomic and healthcare inequalities and the importance and weaknesses of SUS in Brazil. This work indicates the need to revert the disinvestment in the universal public system, a fundamental policy for reduction of inequities in the country.

Effectiveness of BNT162b2 and ChAdOx1 against SARS-CoV-2 household transmission: a prospective cohort study in England

Background

The ability of SARS-CoV-2 vaccines to protect against infection and onward transmission determines whether immunisation can control global circulation. We estimated the effectiveness of Pfizer-BioNTech mRNA vaccine (BNT162b2) and Oxford AstraZeneca adenovirus vector vaccine (ChAdOx1) vaccines against acquisition and transmission of the Alpha and Delta variants in a prospective household study in England.

Methods

Households were recruited based on adult purported index cases testing positive after reverse transcription-quantitative (RT-q)PCR testing of oral-nasal swabs. Purported index cases and their household contacts took oral-nasal swabs on days 1, 3 and 7 after enrolment and a subset of the PCR-positive swabs underwent genomic sequencing conducted on a subset. We used Bayesian logistic regression to infer vaccine effectiveness against acquisition and transmission, adjusted for age, vaccination history and variant.

Results

Between 2 February 2021 and 10 September 2021, 213 index cases and 312 contacts were followed up. After excluding households lacking genomic proximity (N=2) or with unlikely serial intervals (N=16), 195 households with 278 contacts remained, of whom 113 (41%) became PCR positive. Delta lineages had 1.53 times the risk (95% Credible Interval: 1.04 - 2.20) of transmission than Alpha; contacts older than 18 years old were 1.48 (1.20 - 1.91) and 1.02 (0.93 - 1.16) times more likely to acquire an Alpha or Delta infection than children. Effectiveness of two doses of BNT162b2 against transmission of Delta was 36% (-1%, 66%) and 49% (18%, 73%) for ChAdOx1, similar to their effectiveness for Alpha. Protection against infection with Alpha was higher than for Delta, 69% (9%, 95%) vs. 18% (-11%, 59%), respectively, for BNT162b2 and 24% (-41%, 72%) vs. 9% (-15%, 42%), respectively, for ChAdOx1.

Conclusions

BNT162b2 and ChAdOx1 reduce transmission of the Delta variant from breakthrough infections in the household setting, although their protection against infection within this setting is low.

Assessing the real-world effectiveness of five SARS-CoV-2 vaccines in a cohort of Mexican pensioners: a nationwide nested test-negative design study

Background

Despite the extensive distribution of COVID-19 vaccines across Latin America, research on their real-world performance remains limited. We aimed to evaluate the effectiveness of five vaccines (BNT162b2, AZD1222, CoronaVac, Gam-COVID-Vac, and Ad5-nCoV) in a cohort of 2,559,792 pensioners covered by the Mexican Institute of Social Security.

Methods

We conducted a nested test-negative design study on 28,271 individuals tested for SARS-CoV-2 infection between April and November 2021, accounting for 29,226 separate episodes. We used mixed-effects logistic regression models to estimate the vaccine effectiveness (VE) in fully vaccinated individuals for symptomatic infection, hospitalization, severe disease, and death.

Findings

The median age of the study population was 70 years (interquartile range 65-76) and 76.4% (21,598/28,271) were male. VE rates were 56.3%, 75.3%, 79.7%, and 79.8% against symptomatic infection (95% confidence interval [CI]: 53.5-59.0), hospitalization (95% CI: 73.4-77.0), severe disease (95% CI: 78.0-81.3), and death (95% CI: 78.1-81.4), respectively. When evaluating vaccines individually, all showed moderate to high VE, with the best being BNT162b2 (symptomatic infection, 69.8%, 95% CI: 67.3-72.0; hospitalization, 84.1%, 95% CI: 82.5-85.6; severe disease, 88.2%, 95% CI: 86.7-89.5; and death, 88.3%, 95% CI: 86.9-89.6) and Gam-COVID-Vac (symptomatic infection, 70.0%, 95% CI: 64.8-74.4; hospitalization, 86.8%, 95% CI: 83.7-89.3; severe disease, 91.9%, 95% CI: 89.4-93.9; and death, 92.0%, 95% CI: 89.5-93.9).

Interpretation

All five SARS-CoV-2 vaccines available for this population showed moderate to high levels of protection against COVID-19 and its progression to severe outcomes.

Funding

Fundación IMSS, México.

The Impact of CoronaVac Vaccination on 28-day Mortality Rate of Critically Ill Patients with COVID-19 in Türkiye

Background

Vaccines against coronavirus disease-19 (COVID-19) have been effective in preventing symptomatic diseases, hospitalizations, and intensive care unit (ICU) admissions. However, data regarding the effectiveness of COVID-19 vaccines in reducing mortality among critically ill patients with COVID-19 remains unclear.

Aims

To determine the vaccination status and investigate the impact of the COVID-19 vaccine on the 28-day mortality in critically ill patients with COVID-19.

Study Design

Multicenter prospective observational clinical study.

Methods

This study was conducted in 60 hospitals with ICUs managing critically ill patients with COVID-19. Patients aged ≥ 18 years with confirmed COVID-19 who were admitted to the ICU were included. The present study had two phases. The first phase was designed as a one-day point prevalence study, and demographic and clinical findings were evaluated. In the second phase, the 28-day mortality was evaluated.

Results

As of August 11, 2021, 921 patients were enrolled in the study. The mean age of the patients was 65.42 ± 16.74 years, and 48.6% (n = 448) were female. Among the critically ill patients with COVID-19, 52.6% (n = 484) were unvaccinated, 7.7% (n = 71) were incompletely vaccinated, and 39.8% (n = 366) were fully vaccinated. A subgroup analysis of 817 patients who were unvaccinated (n = 484) or who had received two doses of the CoronaVac vaccine (n = 333) was performed. The 28-day mortality rate was 56.8% (n = 275) and 57.4% (n = 191) in the unvaccinated and two-dose CoronaVac groups, respectively. The 28-day mortality was associated with age, hypertension, the number of comorbidities, type of respiratory support, and APACHE II and sequential organ failure assessment scores (p < 0.05). The odds ratio for the 28-day mortality among those who had received two doses of CoronaVac was 0.591 (95% confidence interval: 0.413-0.848) (p = 0.004).

Conclusion

Vaccination with at least two doses of CoronaVac within six months significantly decreased mortality in vaccinated patients than in unvaccinated patients.

Effectiveness of BNT162b2 and CoronaVac vaccines against omicron in children aged 5 to 11 years

BACKGROUND

This study aimed to estimate vaccine effectiveness (VE) against omicron variant infection and severe corona virus disease 2019 (COVID-19) in children aged 5-11 years hospitalized with acute respiratory syndrome.

METHODS

A test-negative, case-control analysis was conducted from February 2022 to June 2022. We enrolled 6950 eligible children, including 1102 cases and 5848 controls. VE was calculated after immunization with one and two doses of BNT162b2 or CoronaVac. The outcomes were hospitalization with acute respiratory symptoms and detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe COVID-19. The adjusted odds ratio for the association of prior vaccination and outcomes was used to estimate VE.

RESULTS

For fully vaccinated children, the overall estimated VE against hospitalization with SARS-CoV-2 infection was 42% [95% confidence interval (CI) 26 to 54]. VE peaked at 29-42 days (67%, 95% CI 40% to 82%) and then declined to 19% (95% CI, - 20% to 45%) at 57-120 days after the second dose. The BNT162b2 vaccine had a similar VE against hospitalization with SARS-CoV-2 infection (45%, 95% CI, 20 to 61) compared to the CoronaVac vaccine (40%, 95% CI, 17% to 56%). Among cases, 56 (5%) children died; 53 (94.6%) were not fully vaccinated. For cases, the two-dose schedule effectiveness against ICU admission, need for invasive ventilation, severe illness, and death were 10% (95% CI, - 54%-45%), 22% (95% CI - 70%-68%), 12% (95% CI, - 62%-52%), and 16% (95% CI, - 77%-75%), respectively.

CONCLUSIONS

For hospitalized children aged 5-11 years during the omicron-predominant period in Brazil, two doses of both vaccines had moderate effectiveness against hospitalization with acute respiratory symptoms and SARS-CoV-2 infection and offered limited protection against endpoints of COVID-19 severity.

CoronaVac and BBIBP-CorV vaccines against SARS-CoV-2 during predominant circulation of Omicron BA.5.2 and BF.7 in China, a retrospective cohort study

Pandemic of COVID-19 hit China at the end of 2022. According to China Center for Disease Control and Prevention, Omicron BA.5.2 and BF.7 were the main circulating variants. Chinese people had a high COVID-19 vaccination rate, and the most widely used vaccines were CoronaVac (Sinovac) and BBIBP-CorV (Sinopharm). An online questionnaire was distributed to survey the vaccination history and infection information of China mainland residents during this pandemic. A total of 4250 subjects were included for propensity score matching, 566 unvaccinated subjects and 1072 vaccinated subjects were finally included to analyze the effects of the two vaccines on BA.5.2 and BF.7. The SARS-CoV-2 infection rate was 84.5% in the vaccinated group and 82.3% in the unvaccinated group (p = 0.255). Vaccinated subjects had significantly higher rates of COVID-19-related symptoms, including fever, cough, nasal obstruction, runny nose, and sore throat. However, vaccinated people had lower risk of pneumonia (odds ratio [OR]: 0.467, 95% confidence interval [CI]: 0.286-0.762) and hospitalization (OR: 0.290, 95% CI: 0.097-0.870) due to COVID-19. In general, the current study did not observe the protective effect of CoronaVac and BBIBP CorV against BA.5.2 and BF.7 infection. However, these vaccines can still reduce the risk of adverse outcomes such as pneumonia and hospitalization.

Clinical Severity of SARS-CoV-2 Variants during COVID-19 Vaccination: A Systematic Review and Meta-Analysis

Due to the variation in the SARS-CoV-2 virus, COVID-19 exhibits significant variability in severity. This presents challenges for governments in managing the allocation of healthcare resources and prioritizing health interventions. Clinical severity is also a critical statistical parameter for researchers to quantify the risks of infectious disease, model the transmission of COVID-19, and provide some targeted measures to control the pandemic. To obtain more accurate severity estimates, including confirmed case-hospitalization risk, confirmed case-fatality risk, hospitalization-fatality risk, and hospitalization-ICU risk, we conducted a systematic review and meta-analysis on the clinical severity (including hospitalization, ICU, and fatality risks) of different variants during the period of COVID-19 mass vaccination and provided pooled estimates for each clinical severity metric. All searches were carried out on 1 February 2022 in PubMed for articles published from 1 January 2020 to 1 February 2022. After identifying a total of 3536 studies and excluding 3523 irrelevant studies, 13 studies were included. The severity results show that the Delta and Omicron variants have the highest (6.56%, 0.46%, 19.63%, and 9.06%) and lowest severities (1.51%, 0.04%, 6.01%, and 3.18%), respectively, according to the four clinical severity metrics. Adults over 65 have higher severity levels for all four clinical severity metrics.

Real-world effectiveness of COVID-19 vaccines among Colombian adults: A retrospective, population-based study of the ESPERANZA cohort

COVID-19 vaccines have been essential for reducing the impact of the pandemic; nevertheless, population-based data under real-life conditions are needed to compare their effectiveness in various contexts. The objective of this study was to estimate the effectiveness of vaccines in preventing hospitalization and death from COVID-19 in Colombia under real-life conditions among people aged 18 years and older, according to sex, age, confirmed history of COVID-19 and vaccination series, including the effects of boosters. This investigation was an observational, retrospective, population-based study based on the Colombian cohort "Esperanza". A total of 14,213,409 individuals aged 18 years and older were analyzed, who were matched in a 1:1 ratio of vaccinated to unvaccinated. The study groups consisted of unvaccinated individuals, those with a complete series (CS) and individuals with a CS plus booster. The vaccinated individuals received either homologous or heterologous vaccinations with Ad26.COV2-S, BNT162b2, ChAdOx1 nCoV-19, CoronaVac and mRNA-1273 vaccines. Follow-up was conducted between February 2021 and June 2022. Cox proportional hazards models were used, adjusted for potential confounders, to estimate the effectiveness of different vaccination series. For adults aged 18 years and older, the overall effectiveness of the vaccines in preventing hospitalization was 82.7% (95% CI 82.1-83.2) for CS and 80.2% (95%CI 78.7-81.6) for CS + booster. The effectiveness in preventing death was 86.0% (95%CI 85.5-86.5) for CS and 83.1% (95%CI 81.5-84.5) for CS + booster. Effectiveness decreased with age. While all efficacies were high, CoronaVac offered significantly lower protection, although this improved with a booster. Continued mass vaccination is pivotal, especially in low- and middle-income countries. The study highlights both the real-world effectiveness of these vaccines and the challenges in understanding waning immunity and the influence of different VoC(Variants of Concern) on results.

Effectiveness of the Booster Dose in Protecting against COVID-19, Colombia 2022

Vaccination has proven to be one of the most effective strategies against the COVID-19 pandemic. Several studies have evaluated and confirmed its effectiveness in different populations, particularly in reducing severe outcomes such as hospitalization and death. Some studies have investigated the effectiveness of vaccination against the infection, identifying the need for booster doses. This study aimed to explore the effectiveness of the vaccination schedule on the probability of infection in a sample of Colombian patients during the fourth wave of the COVID-19 pandemic, which was associated with the emergence and predominance of the Omicron variant. A cross-sectional study was conducted on individuals who underwent RT-PCR testing for COVID-19 detection in a dedicated laboratory in Bogotá, Colombia, between 30 December 2021 and 7 February 2022. A total of 1468 subjects was included in the study, of whom 36.6% (n = 538) had a positive PCR test for COVID-19. The comparison between fully vaccinated individuals with a booster dose and those without the booster dose revealed a 28% reduction in the odds of infection (OR = 0.719 CI 0.531-0.971). Age (OR = 1.009 CI 1.001-1.018) and low economic status (OR = 1.812 CI 1.416-2.319) were associated with an increased risk of infection. These findings suggest the need for a booster vaccination in the general population to improve the prevention rates of SARS-CoV-2 infection and mitigate severe outcomes.

Considerations of COVID-19 in Ophthalmology

Since its emergence in early 2020, the SARS-CoV-2 infection has had a significant impact on the entire eye care system. Ophthalmologists have been categorized as a high-risk group for contracting the virus due to the belief that the eye may be a site of inoculation and transmission of the SARS-CoV-2 infection. As a result, clinical ophthalmologists, optometrists, and eyecare professionals have had to familiarize themselves with the ocular manifestations of COVID-19, as well as its treatments and vaccines. The implementation of measures to prevent the transmission of the virus, such as restrictions, lockdowns, telemedicine, and artificial intelligence (AI), have led to substantial and potentially irreversible changes in routine clinical practice, education, and research. This has resulted in the emergence of a new mode of managing patients in a routine clinical setting. This brief review aims to provide an overview of various aspects of COVID-19 in ophthalmology, including the ocular manifestations related to the disease, the modes of transmission of SARS-CoV-2 infection, precautions taken in ophthalmic practice to prevent the spread of the virus, drugs, and vaccines used in the treatment of COVID-19, the impact of the pandemic on patients, clinicians, and the eye care system as a whole, and the future of ophthalmology conditioned by this global pandemic experience.

Evidence of leaky protection following COVID-19 vaccination and SARS-CoV-2 infection in an incarcerated population

Whether SARS-CoV-2 infection and COVID-19 vaccines confer exposure-dependent ("leaky") protection against infection remains unknown. We examined the effect of prior infection, vaccination, and hybrid immunity on infection risk among residents of Connecticut correctional facilities during periods of predominant Omicron and Delta transmission. Residents with cell, cellblock, and no documented exposure to SARS-CoV-2 infected residents were matched by facility and date. During the Omicron period, prior infection, vaccination, and hybrid immunity reduced the infection risk of residents without a documented exposure (HR: 0.36 [0.25-0.54]; 0.57 [0.42-0.78]; 0.24 [0.15-0.39]; respectively) and with cellblock exposures (0.61 [0.49-0.75]; 0.69 [0.58-0.83]; 0.41 [0.31-0.55]; respectively) but not with cell exposures (0.89 [0.58-1.35]; 0.96 [0.64-1.46]; 0.80 [0.46-1.39]; respectively). Associations were similar during the Delta period and when analyses were restricted to tested residents. Although associations may not have been thoroughly adjusted due to dataset limitations, the findings suggest that prior infection and vaccination may be leaky, highlighting the potential benefits of pairing vaccination with non-pharmaceutical interventions in crowded settings.

Nationwide analysis of the impact of COVID-19 in patients with a cardiovascular, oncological or chronic pulmonary disease in the context of an Eastern European country with a low vaccination rate, Bulgaria: March 2020-April 2022

OBJECTIVE

This study focused on Bulgarian patient cohorts harbouring a single documented chronic comorbidity-cardiovascular pathology, an oncological disease or a chronic pulmonary diseases (CPD) comparing the outcomes in fully vaccinated and non-vaccinated populations classified by sex and age groups in ambulatory, hospital and intensive care unit (ICU) settings at the national level.

DESIGN

Retrospective analysis SETTINGS, PARTICIPANTS AND OUTCOME MEASURES: In total, 1 126 946 patients with confirmed COVID-19, on a national level, were retrospectively analysed between March 2020 and April 2022, using data from the Ministry of Health's United Information Portal, launched in March 2020.

RESULTS

Of all the confirmed 247 441 hospitalised cases of COVID-19, 67 723 (27.3%) had documented cardiovascular disease (CVD), 2140 (0.9%) had confirmed solid malignancy (regardless of stage) and 3243 (1.3%) had established CPD as their only chronic pathology. The number of cumulative deaths in each subgroup was 10 165 (in-hospital=5812 and ICU=4353); 4.0% vaccinated (410/10 165, p<0.001), 344 (in-hospital=196 and ICU=148), 4.9% vaccinated (17/344, p<0.001), 494 (in-hospital=287 and ICU=207) and 5.2% vaccinated (26/494, p<0.001), respectively. Statistical significance (p<0.001) was obtained in favour of reduced ambulatory, hospitalisation and both in-hospital and ICU-related mortality in the vaccinated cohorts, and BNT162b2 was the most effective at preventing mortality in all age groups.

CONCLUSIONS

This retrospective analysis shows that patients vaccinated against COVID-19 demonstrated trends of reduced hospitalisations and premature mortality in patients with CVD, solid malignancy or CPD as a single comorbidity.

Effectiveness of homologous or heterologous immunization regimens against SARS-CoV-2 after two doses of inactivated COVID-19 vaccine: A systematic review and meta-analysis

We aimed to evaluate the effectiveness or efficacy of heterologous or homologous COVID-19 vaccine regimens against COVID-19-related outcomes after primary immunization with two doses of CoronaVac or Sinopharm COVID-19 vaccines. PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched up to 31 October 2022. The primary measure was vaccine effectiveness against COVID-19 infection with homologous or heterologous booster. The results showed heterologous and homologous booster significantly improved effectiveness against COVID-19 infection compared to primary immunization. The effectiveness against COVID-19 infection was 89.19% (95%CI 78.49, 99.89) for heterologous mRNA vaccine booster, 87.00% (95%CI 82.14, 91.85) for non-replicating vector vaccine booster, 69.99% (95%CI 52.16, 87.82) for homologous booster, and 51.48% (95%CI 41.75, 61.21) for two doses of inactivated vaccine. Homologous and heterologous regimens were also effective against SARS-CoV-2 variants, and more evidence is still needed to confirm our findings.

The Role of Children in Household Transmission of SARS-CoV-2 Across Four Waves of the Pandemic

BACKGROUND

It is important to understand the dynamics of SARS-CoV-2 transmission in close-contact settings such as households. We hypothesized that children would most often acquire SARS-CoV-2 from a symptomatic adult caregiver.

METHODS

This prospective cohort study was conducted from April 2020 to July 2022 in a low-resource, urban settlement in Brazil. We recruited families who brought their children to a public clinic. We collected nasopharyngeal and oral swabs from household members and tracked symptoms and vaccination.

RESULTS

In total, 1256 participants in 298 households were tested for SARS-CoV-2. A total of 4073 RT-PCR tests were run with 893 SARS-CoV-2 positive results (21.9%). SARS-CoV-2 cases were defined as isolated cases (N = 158) or well-defined transmission events (N = 175). The risk of household transmission was lower if the index case was a child (OR: 0.3 [95% CI: 0.16-0.55], P < .001) or was vaccinated (OR: 0.29 [95% CI: 0.1-0.85], P = .024), and higher if the index was symptomatic (OR: 2.53 [95% CI: 1.51-4.26], P < .001). The secondary attack rate for child index cases to child contacts was 0.29, whereas the secondary attack rate for adult index cases to child contacts was 0.47 (P = .08).

CONCLUSIONS

In this community, children were significantly less infectious to their household contacts than adolescents or adults. Most children were infected by a symptomatic adult, usually their mother. There was a double benefit of vaccination as it protected the vaccine from severe illness and prevented onward transmission to household contacts. Our findings may also be valid for similar populations throughout Latin America.

Vaccine adjuvants: mechanisms and platforms

Adjuvants are indispensable components of vaccines. Despite being widely used in vaccines, their action mechanisms are not yet clear. With a greater understanding of the mechanisms by which the innate immune response controls the antigen-specific response, the adjuvants' action mechanisms are beginning to be elucidated. Adjuvants can be categorized as immunostimulants and delivery systems. Immunostimulants are danger signal molecules that lead to the maturation and activation of antigen-presenting cells (APCs) by targeting Toll-like receptors (TLRs) and other pattern recognition receptors (PRRs) to promote the production of antigen signals and co-stimulatory signals, which in turn enhance the adaptive immune responses. On the other hand, delivery systems are carrier materials that facilitate antigen presentation by prolonging the bioavailability of the loaded antigens, as well as targeting antigens to lymph nodes or APCs. The adjuvants' action mechanisms are systematically summarized at the beginning of this review. This is followed by an introduction of the mechanisms, properties, and progress of classical vaccine adjuvants. Furthermore, since some of the adjuvants under investigation exhibit greater immune activation potency than classical adjuvants, which could compensate for the deficiencies of classical adjuvants, a summary of the adjuvant platforms under investigation is subsequently presented. Notably, we highlight the different action mechanisms and immunological properties of these adjuvant platforms, which will provide a wide range of options for the rational design of different vaccines. On this basis, this review points out the development prospects of vaccine adjuvants and the problems that should be paid attention to in the future.

Metabolomics acts as a powerful tool for comprehensively evaluating vaccines approved under emergency: a CoronaVac retrospective study

Introduction

To control the COVID-19 pandemic, great efforts have been made to realize herd immunity by vaccination since 2020. Unfortunately, most of the vaccines against COVID-19 were approved in emergency without a full-cycle and comprehensive evaluation process as recommended to the previous vaccines. Metabolome has a close tie with the phenotype and can sensitively reflect the responses to stimuli, rendering metabolomic analysis have the potential to appraise and monitor vaccine effects authentically.

Methods

In this study, a retrospective study was carried out for 330 Chinese volunteers receiving recommended two-dose CoronaVac, a vaccine approved in emergency in 2020. Venous blood was sampled before and after vaccination at 5 separate time points for all the recipients. Routine clinical laboratory analysis, metabolomic and lipidomic analysis data were collected.

Results and discussion

It was found that the serum antibody-positive rate of this population was around 81.82%. Most of the laboratory parameters were slightly perturbated within the relevant reference intervals after vaccination. The metabolomic and lipidomic analyses showed that the metabolic shift after inoculation was mainly in the glycolysis, tricarboxylic acid cycle, amino acid metabolism, urea cycle, as well as microbe-related metabolism (bile acid metabolism, tryptophan metabolism and phenylalanine metabolism). Time-course metabolome changes were found in parallel with the progress of immunity establishment and peripheral immune cell counting fluctuation, proving metabolomics analysis was an applicable solution to evaluate immune effects complementary to traditional antibody detection. Taurocholic acid, lysophosphatidylcholine 16:0 sn-1, glutamic acid, and phenylalanine were defined as valuable metabolite markers to indicate the establishment of immunity after vaccination. Integrated with the traditional laboratory analysis, this study provided a feasible metabolomics-based solution to relatively comprehensively evaluate vaccines approved under emergency.

Effectiveness of inactivated COVID-19 vaccines against SARS-CoV-2 infections among healthcare personnel in Pakistan: a test-negative case-control study

OBJECTIVE

During the COVID-19 pandemic, several vaccines that were efficacious in randomised controlled trials were authorised for mass vaccination. In developing countries, inactivated vaccines were widely administered. While inactivated vaccines have been deemed effective in reducing disease severity, for healthcare personnel (HCP), effectiveness against SARS-CoV-2 infections is essential to reduce the risk to vulnerable patients and ensure a stable healthcare workforce. There are limited studies examining inactivated vaccines' effectiveness against SARS-CoV-2 variants of concern (VOCs) in real-world settings. We estimated the effectiveness of inactivated vaccines (BBIBP-CorV and CoronaVac) against reverse transcription PCR (RT-PCR)-confirmed SARS-CoV-2 infections among HCP in the setting of emerging SARS-CoV-2 VOCs in Pakistan.

DESIGN

A retrospective matched, test-negative case-control analysis using existing data from an Employee Health database on HCP at a large, private healthcare system in Pakistan.

PARTICIPANTS

4599 HCP were tested between 1 April and 30 September 2021. Each case (PCR positive) was matched to two to six controls (PCR negative) by the date of the RT-PCR test (±7 days) to reduce bias.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was vaccine effectiveness (VE) against SARS-CoV-2 infection. The secondary outcome was VE against symptomatic SARS-CoV-2 infection. Per cent VE was calculated using (1-OR)*100, with the OR of getting a PCR-confirmed SARS-COV-2 infection estimated using conditional logistic regression, after adjusting for age, gender, work area and history of SARS-CoV-2 infection.

RESULTS

Inactivated vaccines were ineffective against SARS-CoV-2 infections after receiving the first dose (VE 17%, 95% CI -10, 39; p=0.261). They showed modest effectiveness ≥14 days after the second dose against SARS-CoV-2 infections (VE 30%, 95% CI 7, 48; p=0.015) and symptomatic SARS-CoV-2 infections (VE 33%, 95% CI 6, 52; p=0.002).

CONCLUSIONS

Inactivated vaccines show modest effectiveness against SARS-CoV-2 infections in the setting of emerging VOCs. This builds a strong case for boosters and/or additional vaccination.

A Review of Inactivated COVID-19 Vaccine Development in China: Focusing on Safety and Efficacy in Special Populations

The coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been widespread globally, and vaccination is critical for preventing further spread or resurgence of the outbreak. Inactivated vaccines made from whole inactivated SARS-CoV-2 virus particles generated in Vero cells are currently the most widely used COVID-19 vaccines, with China being the largest producer of inactivated vaccines. As a result, the focus of this review is on inactivated vaccines, with a multidimensional analysis of the development process, platforms, safety, and efficacy in special populations. Overall, inactivated vaccines are a safe option, and we hope that the review will serve as a foundation for further development of COVID-19 vaccines, thus strengthening the defense against the pandemic caused by SARS-CoV-2.

Effects of vaccination against COVID-19 on the emotional health of older adults

Background: The COVID-19 pandemic significantly impacted the mental and emotional health of the elderly, especially those from low to middle-income countries. However, COVID-19 vaccination may reduce this influence. Therefore, we aimed to estimate the effect of vaccination against COVID-19 on the emotional health of older adults. Methods: We selected a national, random, and stratified sample of non-hospitalized adults aged 60 to 79 years from Peru who intended to receive or had already received the COVID-19 vaccine during recruitment. During June and July 2021, the assessed outcomes were the fear, anxiety, and worry about COVID-19, general anxiety, and depression at baseline and after a month. We estimated the adjusted odds ratios (aOR) and 95% confidence intervals (95% CI) for each altered emotional health outcomes in those who had one and two doses, compared with those who were not vaccinated using multilevel logistic regression with mixed effects. Results: We recruited 861 older adults with 20.8% of loss to follow-up. At baseline, 43.9% had received only one dose of the vaccine, and 49.1% had two doses. In the analysis during follow-up, those who had two doses had less fear (aOR: 0.19; CI 95%: 0.07 to 0.51) and anxiety to COVID-19 (aOR: 0.45; CI 95%: 0.22 to 0.89), compared to unvaccinated. We observed no effects in those with only one dose. Conclusions: Two doses of COVID-19 vaccination in older adults improves their perception of COVID-19 infection consequences. This information could be integrated into the vaccination campaign as an additional beneficial effect.

Immunogenicity of NVX-CoV2373 in PREVENT-19: A Phase 3, Randomized, Placebo-Controlled Trial in Adults in the United States and Mexico

Background

NVX-CoV2373, an adjuvanted, recombinant SARS-CoV-2 spike (rS) protein vaccine, consistently demonstrated protective efficacy against COVID-19 in clinical trials and has received regulatory authorizations or approvals worldwide.

Methods

PREVENT-19 (NCT04611802) is a phase 3, randomized, observer-blinded, placebo-controlled trial evaluating safety, immunogenicity, and efficacy of NVX-CoV2373 in ≈30 000 participants ≥18 years in the United States and Mexico. Vaccine humoral immune response (ie, serum immunoglobulin [IgG] antibodies, hACE2 receptor binding inhibition antibodies, and neutralizing antibodies to SARS-CoV-2) (ancestral strain) was assessed in 1200 participants randomly selected and equally divided between participants 18-64 and ≥65 years.

Results

In the per protocol analysis, NVX-CoV2373 induced vigorous serum antibody responses among the 1063 analyzed participants who were SARS-CoV-2 seronegative at baseline, received both doses of study treatment, and had serology results available 2 weeks after dose 2. Geometric mean (GM) responses in both younger and older adults were higher among recipients of vaccine versus placebo for IgG (64 259 vs 121 and 37 750 vs 133 ELISA units, respectively), hACE2 receptor binding inhibition GM titers (GMTs) (222 vs 5 and 136 vs 5, respectively), and neutralizing antibody GMTs (1303 vs 11 and 900 vs 11, respectively). Humoral responses were 30-40% lower in participants ≥65 years or HIV-positive; however, seroconversion rates were high and comparable between the age cohorts, regardless of HIV serostatus.

Conclusions

NVX-CoV2373 elicited robust humoral immune responses against ancestral SARS-CoV-2 virus 2 weeks following the second vaccination in adult PREVENT-19 participants, consistent with previously reported high vaccine efficacy.

Sequential Administration of SARS-CoV-2 Strains-Based Vaccines Effectively Induces Potent Immune Responses against Previously Unexposed Omicron Strain

In the past few years, the continuous pandemic of COVID-19 caused by SARS-CoV-2 has placed a huge burden on public health. In order to effectively deal with the emergence of new SARS-CoV-2 variants, it becomes meaningful to further enhance the immune responses of individuals who have completed the first-generation vaccination. To understand whether sequential administration using different variant sequence-based inactivated vaccines could induce better immunity against the forthcoming variants, we tried five inactivated vaccine combinations in a mouse model and compared their immune responses. Our results showed that the sequential strategies have a significant advantage over homologous immunization by inducing robust antigen-specific T cell immune responses in the early stages of immunization. Furthermore, the three-dose vaccination strategies in our research elicited better neutralizing antibody responses against the BA.2 Omicron strain. These data provide scientific clues for finding the optimal strategy within the existing vaccine platform in generating cross-immunity against multiple variants including previously unexposed strains.

Real-world effectiveness and factors associated with effectiveness of inactivated SARS-CoV-2 vaccines: a systematic review and meta-regression analysis

BACKGROUND

The two inactivated SARS-CoV-2 vaccines, CoronaVac and BBIBP-CorV, have been widely used to control the COVID-19 pandemic. The influence of multiple factors on inactivated vaccine effectiveness (VE) during long-term use and against variants is not well understood.

METHODS

We selected published or preprinted articles from PubMed, Embase, Scopus, Web of Science, medRxiv, BioRxiv, and the WHO COVID-19 database by 31 August 2022. We included observational studies that assessed the VE of completed primary series or homologous booster against SARS-CoV-2 infection or severe COVID-19. We used DerSimonian and Laird random-effects models to calculate pooled estimates and conducted multiple meta-regression with an information theoretic approach based on Akaike's Information Criterion to select the model and identify the factors associated with VE.

RESULTS

Fifty-one eligible studies with 151 estimates were included. For prevention of infection, VE associated with study region, variants, and time since vaccination; VE was significantly decreased against Omicron compared to Alpha (P = 0.021), primary series VE was 52.8% (95% CI, 43.3 to 60.7%) against Delta and 16.4% (95% CI, 9.5 to 22.8%) against Omicron, and booster dose VE was 65.2% (95% CI, 48.3 to 76.6%) against Delta and 20.3% (95% CI, 10.5 to 28.0%) against Omicron; primary VE decreased significantly after 180 days (P = 0.022). For the prevention of severe COVID-19, VE associated with vaccine doses, age, study region, variants, study design, and study population type; booster VE increased significantly (P = 0.001) compared to primary; though VE decreased significantly against Gamma (P = 0.034), Delta (P = 0.001), and Omicron (P = 0.001) compared to Alpha, primary and booster VEs were all above 60% against each variant.

CONCLUSIONS

Inactivated vaccine protection against SARS-CoV-2 infection was moderate, decreased significantly after 6 months following primary vaccination, and was restored by booster vaccination. VE against severe COVID-19 was greatest after boosting and did not decrease over time, sustained for over 6 months after the primary series, and more evidence is needed to assess the duration of booster VE. VE varied by variants, most notably against Omicron. It is necessary to ensure booster vaccination of everyone eligible for SARS-CoV-2 vaccines and continue monitoring virus evolution and VE.

TRIAL REGISTRATION

PROSPERO, CRD42022353272.

Cellular and Humoral Immune Responses to Vaccination for COVID-19 Are Negatively Impacted by Senescent T Cells: A Case Report

BACKGROUND

Herein, we aimed to follow up on the cellular and humoral immune responses of a group of individuals who initially received the CoronaVac vaccine, followed by a booster with the Pfizer vaccine.

METHODS

Blood samples were collected: before and 30 days after the first CoronaVac dose; 30, 90, and 180 days after the second CoronaVac dose, and also 20 days after the booster with the Pfizer vaccine.

RESULTS

Whilst the positivity to gamma interferon-type cellular response increased after the first CoronaVac dose, neutralizing and IgG antibody levels only raised 30 days after the second dose, followed by a drop in these responses after 90 and 180 days. The booster with the Pfizer vaccine elicited a robust cellular and humoral response. A higher number of double-negative and senescent T cells, as well as increased pro-inflammatory cytokines levels were found in the participants with lower humoral immune responses.

CONCLUSION

CoronaVac elicited an early cellular response, followed by a humoral response, which dropped 90 days after the second dose. The booster with the Pfizer vaccine significantly enhanced these responses. Furthermore, a pro-inflammatory systemic status was found in volunteers who presented senescent T cells, which could putatively impair the immune response to vaccination.

Levels and durability of neutralizing antibodies against SARS-CoV-2 Omicron and other variants after ChAdOx-1 or BNT162b2 booster in CoronaVac-primed elderly individuals

The outbreak of the SARS-CoV-2 Omicron variant raised the need for vaccine boosting. We evaluated the efficiency of the third booster vaccine, ChAdOx-1 or BNT162b2, in causing a neutralizing antibody (NAb) response and its durability against the Omicron and other variants in elderly individuals previously vaccinated with 2-dose CoronaVac inactivated vaccine. After receiving 2-dose CoronaVac, only 2.2% of subjects had NAbs against the Omicron variant above the cut-off value. Four weeks after boosting, the number of subjects who had NAb levels above the cut-off values in the ChAdOx-1 and BNT162b2 vaccine boosting groups increased to 41.7% and 54.5%, respectively. However, after 12 and 24 weeks of boosting with any vaccines, NAb levels against the Omicron variant dramatically waned. Twenty-four weeks after boosting, only 2% had high levels of NAbs against the Omicron variant. Compared to other variants, the Omicron variant was less responsive to boosting vaccines. The waning rate of NAb levels for the Omicron variant was much faster than that observed in the Alpha, Beta and Delta variants. To combat the Omicron variant, the fourth booster dose is, therefore, recommended for elderly individuals.

The effectiveness of COVID-19 vaccines against severe cases and deaths in Brazil from 2021 to 2022: a registry-based study

Background

Brazil started the COVID-19 mass vaccination in January 2021 with CoronaVac and ChAdOx1, followed by BNT162b2 and Ad26.COV2.S vaccines. By the end of 2021, more than 317 million vaccine doses were administered in the adult population. This study aimed at estimating the effectiveness of the primary series of COVID-19 vaccination and booster shots in protecting against severe cases and deaths in Brazil during the first year of vaccination.

Methods

A cohort dataset of over 158 million vaccination and severe cases records linked from official national registries was analyzed via a mixed-effects Poisson model, adjusted for age, state of residence, time after immunization, and calendar time to estimate the absolute vaccine effectiveness of the primary series of vaccination and the relative effectiveness of the booster. The method permitted analysis of effectiveness against hospitalizations and deaths, including in the periods of variant dominance.

Findings

Vaccine effectiveness against severe cases and deaths remained over 25% and 50%, respectively, after 19 weeks from primary vaccination of BNT162b2, ChAdOx1, or CoronaVac vaccines. The boosters conferred greater protection than the primary series of vaccination, with heterologous boosters providing marginally greater protection than homologous. The effectiveness against hospitalization during the Omicron dominance in the 60+ years old population started at 61.7% (95% CI, 26.1-86.2) for ChAdOx1, 95.6% (95% CI, 82.4-99.9) for CoronaVac, and 72.3% (95% CI, 51.4-87.4) for the BNT162b2 vaccine.

Interpretation

This study provides real-world evidence of the effectiveness of COVID-19 vaccination in Brazil, including during the Omicron wave, demonstrating protection even after waning effectiveness. Comparisons of the effectiveness among different vaccines require caution due to potential bias effects related to age groups, periods in the pandemic, and eventual behavioural changes.

Funding

Fundação Oswaldo Cruz (FIOCRUZ), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ), Pan American Health Organization (PAHO), Departamento de Ciência e Tecnologia da Secretaria de Ciência, Tecnologia, Inovação e Insumos Estratégicos em Saúde do Ministério da Saúde do Brasil (DECIT/SCTIE/MS).

Effectiveness of a nationwide COVID-19 vaccination program in Mexico against symptomatic COVID-19, hospitalizations, and death: a retrospective analysis of national surveillance data

OBJECTIVES

Vaccination has been effective in ameliorating the impact of COVID-19. Here, we report vaccine effectiveness (VE) of the nationally available COVID-19 vaccines in Mexico.

METHODS

Retrospective analysis of a COVID-19 surveillance system to assess the VE of the BNT162b2, messenger RNA (mRNA)-12732, Gam-COVID-Vac, Ad5-nCoV, Ad26.COV2.S, ChAdOx1, and CoronaVac vaccines against SARS-CoV-2 infection, COVID-19 hospitalization, and death in Mexico. The VE was estimated using time-varying Cox proportional hazard models in vaccinated and unvaccinated adults, adjusted for age, sex, and comorbidities. VE was also estimated for adults with diabetes, aged ≥60 years, and comparing the predominance of SARS-CoV-2 variants B.1.1.519 and B.1.617.2.

RESULTS

We assessed 793,487 vaccinated and 4,792,338 unvaccinated adults between December 24, 2020 and September 27, 2021. The VE against SARS-CoV-2 infection was the highest for fully vaccinated individuals with mRNA-12732 (91.5%, 95% confidence interval [CI] 90.3-92.4) and Ad26.COV2.S (82.2%, 95% CI 81.4-82.9); for COVID-19 hospitalization, BNT162b2 (84.3%, 95% CI 83.6-84.9) and Gam-COVID-Vac (81.4% 95% CI 79.5-83.1), and for mortality, BNT162b2 (89.8%, 95% CI 89.2-90.2) and mRNA-12732 (93.5%, 95% CI 86.0-97.0). The VE decreased for all vaccines in adults aged ≥60 years, people with diabetes, and periods of Delta variant predominance.

CONCLUSION

All the vaccines implemented in Mexico were effective against SARS-CoV-2 infection, COVID-19 hospitalization, and death. Mass vaccination with multiple vaccines is useful to maximize vaccination coverage.

The effectiveness of COVID-19 vaccines in Latin America, 2021: a multicenter regional case–control study

Background

As of September 2022, nearly 1.3 billion doses of COVID-19 vaccine products have been administered in Latin America and the Caribbean, where 27% of global COVID-19 deaths have occurred. This study aimed to estimate the effectiveness of COVID-19 vaccines against lab-confirmed COVID-19 related hospitalizations and deaths among adults in Argentina, Brazil, Chile, and Colombia.

Methods

Using a test-negative case control design, we evaluated the effectiveness of a primary vaccination series considering six COVID-19 vaccine products (Sputnik V, mRNA-1273, CoronaVac, ChAdOx1, BNT162b2, Ad26.COV2.S) against lab-confirmed COVID-19 hospitalizations and deaths among 83,708 hospitalized adults from February–December, 2021. Data from hospitalization records, COVID surveillance, and vaccination registries were used. Vaccine effectiveness was estimated using logistic regression ((1-OR) x 100).

Findings

The average age of participants was 56.7 (SD = 17.5), and 45,894 (54.8%) were male. Adjusted VE (aVE) estimates for full vaccination against hospitalization were 82% for mRNA-1273 (95% confidence interval (CI) = −30 to 98%), 76% (71%–81%) for BNT162b2, 65% (61–68%) for ChAdOx1, 57% (10–79%) for Sputnik V, 53% (50–56%) for CoronaVac, and 46% (23–62%) for Ad26.COV2.S. Estimates, particularly for CoronaVac, varied by variant. Decreasing aVE was estimated as age increased, particularly for CoronaVac and ChAdOx1. aVE estimates against death were generally higher, with 100% (CI not estimated) for mRNA-1273, 82% (69–90%) for BNT162b2, 73% (69–77%) for ChAdOx1, 65% (60–67%) for CoronaVac, 38% (−75 to 78%) for Sputnik V, 6% (−58 to 44%) for Ad26.COV2.S.

Interpretation

Primary series vaccination with available COVID-19 vaccine products was effective against COVID-19 hospitalization and mortality. Effectiveness varied by product and declined with increasing age.

Funding

This study was funded by the Pan-American Health Organization (10.13039/100011893PAHO, World Health Organization (WHO)). PAHO convened and led the study implementation.