Vaccine effectiveness of primary series and booster doses against covid-19 associated hospital admissions in the United States: living test negative design study

Healthcare workers' willingness to receive COVID-19 booster dose and associated factors in the Democratic Republic of the Congo

The COVID-19 booster dose is considered an important adjunct for the control of the COVID-19 pandemic due to reports of reduced immunity in fully vaccinated individuals. The aims of this study were to assess healthcare workers' intention to receive the booster dose of COVID-19 vaccine and to identify predictive factors among healthcare workers. A cross-sectional study was conducted among healthcare workers selected in two provinces, Kasai Oriental, and Haut-Lomami. Data were collected using a questionnaire administered through structured face-to-face interviews, with respondents using a pre-tested questionnaire set up on the Open Data Kit (ODK Collect). All data were analyzed using SPSS v26.0 (IBM Corporation, Armonk, NY, USA). Vaccination coverage for COVID-19, considering declarations by health workers, is around 85.9% for the province of Kasai Oriental and 85.8% for Haut-Lomami. A total of 975 responses were collected, 71.4% of health workers at Kasai Oriental and 66.4% from Haut-Lomami declared a definite willingness to receive a COVID-19 vaccine booster. The duration of protection was the main reason for accepting a booster COVID-19 dose for 64.6% of the respondents. Logistic regression analysis showed that having chronic diseases (aOR = 2.95 [1.65-5.28]), having already received one of the COVID-19 vaccines (aOR = 2.72 [1.43-5. 19]); the belief that only high-risk individuals, such as healthcare professionals and elderly people suffering from other illnesses, needed a booster dose (aOR = 1.75 [1.10-2.81]). Considering the burden of COVID-19, a high acceptance rate for booster doses could be essential to control the pandemic. Our results are novel and could help policymakers design and implement specific COVID-19 vaccination programs to reduce reluctance to seek booster vaccination.

Viral and Host Factors Are Associated With Mortality in Hospitalized Patients With COVID-19

BACKGROUND

Persistent mortality in adults hospitalized due to acute COVID-19 justifies pursuit of disease mechanisms and potential therapies. The aim was to evaluate which virus and host response factors were associated with mortality risk among participants in Therapeutics for Inpatients with COVID-19 (TICO/ACTIV-3) trials.

METHODS

A secondary analysis of 2625 adults hospitalized for acute SARS-CoV-2 infection randomized to 1 of 5 antiviral products or matched placebo in 114 centers on 4 continents. Uniform, site-level collection of participant baseline clinical variables was performed. Research laboratories assayed baseline upper respiratory swabs for SARS-CoV-2 viral RNA and plasma for anti-SARS-CoV-2 antibodies, SARS-CoV-2 nucleocapsid antigen (viral Ag), and interleukin-6 (IL-6). Associations between factors and time to mortality by 90 days were assessed using univariate and multivariable Cox proportional hazards models.

RESULTS

Viral Ag ≥4500 ng/L (vs <200 ng/L; adjusted hazard ratio [aHR], 2.07; 1.29-3.34), viral RNA (<35 000 copies/mL [aHR, 2.42; 1.09-5.34], ≥35 000 copies/mL [aHR, 2.84; 1.29-6.28], vs below detection), respiratory support (<4 L O2 [aHR, 1.84; 1.06-3.22]; ≥4 L O2 [aHR, 4.41; 2.63-7.39], or noninvasive ventilation/high-flow nasal cannula [aHR, 11.30; 6.46-19.75] vs no oxygen), renal impairment (aHR, 1.77; 1.29-2.42), and IL-6 >5.8 ng/L (aHR, 2.54 [1.74-3.70] vs ≤5.8 ng/L) were significantly associated with mortality risk in final adjusted analyses. Viral Ag, viral RNA, and IL-6 were not measured in real-time.

CONCLUSIONS

Baseline virus-specific, clinical, and biological variables are strongly associated with mortality risk within 90 days, revealing potential pathogen and host-response therapeutic targets for acute COVID-19 disease.

Uptake, effectiveness and safety of COVID-19 vaccines in individuals at clinical risk due to immunosuppressive drug therapy or transplantation procedures: a population-based cohort study in England

BACKGROUND

Immunocompromised individuals are at increased risk of severe COVID-19 outcomes, underscoring the importance of COVID-19 vaccination in this population. The lack of comprehensive real-world data on vaccine uptake, effectiveness and safety in these individuals presents a critical knowledge gap, highlighting the urgency to better understand and address the unique challenges faced by immunocompromised individuals in the context of COVID-19 vaccination.

METHODS

We analysed data from 12,274,946 people in the UK aged > 12 years from 01/12/2020 to 11/04/2022. Of these, 583,541 (4.8%) were immunocompromised due to immunosuppressive drugs, organ transplants, dialysis or chemotherapy. We undertook a cohort analysis to determine COVID-19 vaccine uptake, nested case-control analyses adjusted for comorbidities and sociodemographic characteristics to determine effectiveness of vaccination against COVID-19 hospitalisation, ICU admission and death, and a self-controlled case series assessing vaccine safety for pre-specified adverse events of interest.

RESULTS

Overall, 93.7% of immunocompromised individuals received at least one COVID-19 vaccine dose, with 80.4% having received three or more doses. Uptake reduced with increasing deprivation (hazard ratio [HR] 0.78 [95%CI 0.77-0.79] in the most deprived quintile compared to the least deprived quintile for the first dose). Estimated vaccine effectiveness against COVID-19 hospitalisation 2-6 weeks after the second and third doses compared to unvaccinated was 78% (95%CI 72-83) and 91% (95%CI 88-93) in the immunocompromised population, versus 85% (95%CI 83-86) and 86% (95%CI 85-89), respectively, for the general population. Results showed COVID-19 vaccines were protective against intensive care unit (ICU) admission and death in both populations, with effectiveness of over 92% against COVID-19-related death and up to 95% in reducing ICU admissions for both populations following the third dose. COVID-19 vaccines were generally safe for immunocompromised individuals, though specific doses of ChAdOx1, mRNA-1273 and BNT162b2 raised risks of specific cardiovascular/neurological conditions.

CONCLUSIONS

COVID-19 vaccine uptake is high in immunocompromised individuals on immunosuppressive drug therapy or who have undergone transplantation procedures, with documented disparities by deprivation. Findings suggest that COVID-19 vaccines are protective against severe COVID-19 outcomes in this vulnerable population, and show a similar safety profile in immunocompromised individuals and the general population, despite some increased risk of adverse events. These results underscore the importance of ongoing vaccination prioritisation for this clinically at-risk population to maximise protection against severe COVID-19 outcomes.

Non-specific protection against severe COVID-19 associated to typhoid fever and DTP vaccination

Trained immunity (TRAIM) or the enhanced non-specific immune response after primary stimulation by infection or vaccination is a recent but well-recognized concept. To verify its predictions, our objective was to determine the effects of two bacterial vaccines, typhoid fever (TFV) and diphtheria-tetanus-pertussis (DTP) on the infection, hospitalization and death frequencies associated to COVID-19 in a retrospective study on subjects vaccinated or not with TFV and DTP in the 4 years prior to the start of COVID-19 pandemia in the Basque Country (Spain). The studied outcome records were split into two periods according to COVID-19 vaccination, the pre-vaccination (ACV) from March to December 2020 and the post-vaccination (PCV) from September 2021 to June 2022). In total, 13,673 subjects were vaccinated against TFV and 42,997 against DTP. A total of 2,005,084 individual records were studied in the ACV period and 1,436,693 in the PCV period. The proportion of infection, hospitalization and death associated to COVID-19 among controls in ACV was 4.97 %, 7.14 % and 3.54 %, respectively vs. 7.20 %, 2.24 % and 0.10 % among TFV subjects. Regarding DTP, the proportions were 4.97 %, 7.12 % and 3.58 % for controls and 5.79 %, 5.79 % and 0.80 % for vaccinees. In the PCV period, the proportion of infection, hospitalization and death among controls was 21.89 %, 2.62 % and 0.92 %, respectively vs. 31.19 %, 0.76 %, 0.00 % among TFV. For DTP, infection, hospitalization and death proportions were 21.89 %, 2.62 % and 0.92 %, respectively, among controls vs. 32.03 %, 1.85 % and 0.24 % among vaccinated subjects. The corresponding combined ACV and PCV odds ratios (OR) for SARS-CoV2 infection were 1.505 (95%CI 1.455-1.558; p < 0.0001; reduction -41.85 %) and 1.633 (95%CI 1.603-1.662; p < 0.0001; reduction -51.74 %), for TFV and DTP, respectively. Regarding COVID-19 associated hospitalization, the OR were 0.295 (95%CI 0.220-0.396; p = 0.0001; reduction 69.74 %) and 0.667 (95%CI 0.601-0.741; p = 0.0001; reduction 32.44 %), for TFV and DTP, respectively). COVID-19 associated death OR were 0.016 (95%CI 0.002-0.113, p < 0.0001; reduction 98.38 %) and 0.212 (95%CI 0.161-0.280; p = 0.0001; reduction 78.52 %), for TFV and DTP, respectively. We conclude that TRAIM effects by TFV and DTP vaccination in the four years prior to the pandemic SARS-CoV2 were supported by slightly increased infection rates, but strongly reduced COVID-19 associated hospitalization and death rates.

Risk factors for progressing to critical illness in patients with hospital-acquired COVID-19

BACKGROUND/AIMS

Risk factors for progression to critical illness in hospital-acquired coronavirus disease 2019 (COVID-19) remain unknown. Here, we assessed the incidence and risk factors for progression to critical illness and determined their effects on clinical outcomes in patients with hospital-acquired COVID-19.

METHODS

This retrospective cohort study analyzed patients admitted to the tertiary hospital between January 2020 and June 2022 with confirmed hospital-acquired COVID-19. The primary outcome was the progression to critical illness of hospital- acquired COVID-19. Patients were stratified into high-, intermediate-, or low-risk groups by the number of risk factors for progression to critical illness.

RESULTS

In total, 204 patients were included and 37 (18.1%) progressed to critical illness. In the multivariable logistic analysis, patients with preexisting respiratory disease (OR, 3.90; 95% CI, 1.04-15.18), preexisting cardiovascular disease (OR, 3.49; 95% CI, 1.11-11.27), immunocompromised status (OR, 3.18; 95% CI, 1.11-9.16), higher sequential organ failure assessment (SOFA) score (OR, 1.56; 95% CI, 1.28-1.96), and higher clinical frailty scale (OR, 2.49; 95% CI, 1.62-4.13) showed significantly increased risk of progression to critical illness. As the risk of the groups increased, patients were significantly more likely to progress to critical illness and had higher 28-day mortality.

CONCLUSION

Among patients with hospital-acquired COVID-19, preexisting respiratory disease, preexisting cardiovascular disease, immunocompromised status, and higher clinical frailty scale and SOFA scores at baseline were risk factors for progression to critical illness. Patients with these risk factors must be prioritized and appropriately isolated or treated in a timely manner, especially in pandemic settings.

Factors influencing Thai university students' decisions to take COVID-19 vaccine booster doses: a cross-sectional survey

BACKGROUND

We aimed to describe the acceptance of COVID-19 vaccine booster doses and factors influencing this among Thai university students.

METHODS

A cross-sectional survey was conducted between July and September 2022. All university students in Thailand were eligible to participate. We explored the acceptance rate of COVID-19 vaccine booster doses and regular vaccines (if available) among university students. Associations between factors influencing the acceptance of vaccination were analyzed by multiple logistic regression analysis.

RESULTS

A total of 322 participants were surveyed (78.9% female, age 18 to 49 years (mean = 22.6, standard deviation = 5.47)). Most participants (85.7%) were undergraduate students (Bachelor level), and a proportion (84.8%) had a background in health sciences studies. The proportions who accepted booster doses and regular vaccines were 52.8% and 69.3%, respectively. Vaccine accessibility was found to be significantly associated with the acceptance of booster doses (adjusted odds ratio (AOR) = 2.77, 95% confidence interval (CI) = 1.10-6.97), while the availability of scientific evidence (AOR = 3.44, 95% CI = 1.21-9.77) was significantly associated with the acceptance of regular vaccines.

CONCLUSIONS

This study contributes to addressing the knowledge gap regarding acceptance of COVID-19 vaccine booster doses among university students in Thailand. Our findings revealed that vaccine accessibility and the availability of scientific evidence, as well as vaccination costs, influenced individuals' decisions around accepting vaccine booster doses. Further research should focus on the dynamics of vaccine acceptance to facilitate the development of targeted strategies and support vaccination policymaking in Thailand.

Vaccine Effectiveness Against Influenza A-Associated Hospitalization, Organ Failure, and Death: United States, 2022-2023

BACKGROUND

Influenza circulation during the 2022-2023 season in the United States largely returned to pre-coronavirus disease 2019 (COVID-19)-pandemic patterns and levels. Influenza A(H3N2) viruses were detected most frequently this season, predominately clade 3C.2a1b.2a, a close antigenic match to the vaccine strain.

METHODS

To understand effectiveness of the 2022-2023 influenza vaccine against influenza-associated hospitalization, organ failure, and death, a multicenter sentinel surveillance network in the United States prospectively enrolled adults hospitalized with acute respiratory illness between 1 October 2022, and 28 February 2023. Using the test-negative design, vaccine effectiveness (VE) estimates against influenza-associated hospitalization, organ failures, and death were measured by comparing the odds of current-season influenza vaccination in influenza-positive case-patients and influenza-negative, SARS-CoV-2-negative control-patients.

RESULTS

A total of 3707 patients, including 714 influenza cases (33% vaccinated) and 2993 influenza- and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-negative controls (49% vaccinated) were analyzed. VE against influenza-associated hospitalization was 37% (95% confidence interval [CI]: 27%-46%) and varied by age (18-64 years: 47% [30%-60%]; ≥65 years: 28% [10%-43%]), and virus (A[H3N2]: 29% [6%-46%], A[H1N1]: 47% [23%-64%]). VE against more severe influenza-associated outcomes included: 41% (29%-50%) against influenza with hypoxemia treated with supplemental oxygen; 65% (56%-72%) against influenza with respiratory, cardiovascular, or renal failure treated with organ support; and 66% (40%-81%) against influenza with respiratory failure treated with invasive mechanical ventilation.

CONCLUSIONS

During an early 2022-2023 influenza season with a well-matched influenza vaccine, vaccination was associated with reduced risk of influenza-associated hospitalization and organ failure.

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.

Severity of Respiratory Syncytial Virus vs COVID-19 and Influenza Among Hospitalized US Adults

Importance

On June 21, 2023, the Centers for Disease Control and Prevention recommended the first respiratory syncytial virus (RSV) vaccines for adults aged 60 years and older using shared clinical decision-making. Understanding the severity of RSV disease in adults can help guide this clinical decision-making.

Objective

To describe disease severity among adults hospitalized with RSV and compare it with the severity of COVID-19 and influenza disease by vaccination status.

Design, Setting, and Participants

In this cohort study, adults aged 18 years and older admitted to the hospital with acute respiratory illness and laboratory-confirmed RSV, SARS-CoV-2, or influenza infection were prospectively enrolled from 25 hospitals in 20 US states from February 1, 2022, to May 31, 2023. Clinical data during each patient's hospitalization were collected using standardized forms. Data were analyzed from August to October 2023.

Exposures

RSV, SARS-CoV-2, or influenza infection.

Main Outcomes and Measures

Using multivariable logistic regression, severity of RSV disease was compared with COVID-19 and influenza severity, by COVID-19 and influenza vaccination status, for a range of clinical outcomes, including the composite of invasive mechanical ventilation (IMV) and in-hospital death.

Results

Of 7998 adults (median [IQR] age, 67 [54-78] years; 4047 [50.6%] female) included, 484 (6.1%) were hospitalized with RSV, 6422 (80.3%) were hospitalized with COVID-19, and 1092 (13.7%) were hospitalized with influenza. Among patients with RSV, 58 (12.0%) experienced IMV or death, compared with 201 of 1422 unvaccinated patients with COVID-19 (14.1%) and 458 of 5000 vaccinated patients with COVID-19 (9.2%), as well as 72 of 699 unvaccinated patients with influenza (10.3%) and 20 of 393 vaccinated patients with influenza (5.1%). In adjusted analyses, the odds of IMV or in-hospital death were not significantly different among patients hospitalized with RSV and unvaccinated patients hospitalized with COVID-19 (adjusted odds ratio [aOR], 0.82; 95% CI, 0.59-1.13; P = .22) or influenza (aOR, 1.20; 95% CI, 0.82-1.76; P = .35); however, the odds of IMV or death were significantly higher among patients hospitalized with RSV compared with vaccinated patients hospitalized with COVID-19 (aOR, 1.38; 95% CI, 1.02-1.86; P = .03) or influenza disease (aOR, 2.81; 95% CI, 1.62-4.86; P < .001).

Conclusions and Relevance

Among adults hospitalized in this US cohort during the 16 months before the first RSV vaccine recommendations, RSV disease was less common but similar in severity compared with COVID-19 or influenza disease among unvaccinated patients and more severe than COVID-19 or influenza disease among vaccinated patients for the most serious outcomes of IMV or death.

Immunogenicity and safety of a booster dose of a self-amplifying RNA COVID-19 vaccine (ARCT-154) versus BNT162b2 mRNA COVID-19 vaccine: a double-blind, multicentre, randomised, controlled, phase 3, non-inferiority trial

BACKGROUND

Licensed mRNA COVID-19 vaccines require booster doses to sustain SARS-CoV-2-specific responses, creating the need for novel, broadly immunogenic vaccines. We aimed to compare the immunogenicity, safety, and tolerability of ARCT-154-a self-amplifying mRNA vaccine against SARS-CoV-2 D614G variant-with the BNT162b2 (Comirnaty; Pfizer-BioNTech) mRNA vaccine when administered as a fourth-dose booster.

METHODS

This double-blind, multicentre, randomised, controlled, phase 3, non-inferiority trial, conducted at 11 outpatient clinical sites in Japan, enrolled healthy adults aged at least 18 years who had previously been immunised with two doses of an mRNA COVID-19 vaccine (BNT162b2 or mRNA-1273 [Spikevax; Moderna]) followed by a third dose of BNT162b2 at least 3 months before enrolment. Participants were randomly assigned, in a 1:1 ratio using an Interactive Response Technology system with a block size of four, and with stratification by age (18-64 years or ≥65 years) and by interval since last COVID-19 vaccination (<5 months or ≥5 months), to receive either ARCT-154 or BNT162b2 as a fourth-dose booster via deltoid intramuscular injection. Participants and investigators assessing outcomes were masked to group assignment. The primary objective, measured in per-protocol set 1 (consisting of participants with no evidence of previous SARS-CoV-2 infection who received their intended injection according to protocol), was to show that the immune response 28 days after the ARCT-154 vaccine was non-inferior to that of the BNT162b2 vaccine, measured in terms of both pseudovirus neutralising antibody geometric mean titre (GMT) ratios and seroresponse rates against the wild-type Wuhan-Hu-1 strain of SARS-CoV-2. Non-inferiority was declared when the lower limit of the 95% CI of the ARCT-154 to BNT162b2 GMT ratio exceeded 0·67, and when the lower limit for the difference in seroresponse rates exceeded -10%. Key secondary endpoints included the immune response against the omicron BA.4/5 subvariant, which was assessed for non-inferiority and superiority in per-protocol set 1. Safety was assessed in the full analysis set. This study was registered on the Japan Registry for Clinical Trials, jRCT 2071220080, and is ongoing.

FINDINGS

Between Dec 13, 2022, and Feb 25, 2023, we enrolled and randomly assigned 828 participants to receive ARCT-154 (n=420) or BNT162b2 (n=408) vaccines as a fourth-dose booster. In per-protocol set 1, the GMTs of surrogate neutralising antibodies induced against the Wuhan-Hu-1 SARS-CoV-2 strain in the ARCT-154 group (5641 [95% CI 4321-7363]) were non-inferior to those in the BNT162b2 group (3934 [2993-5169]) when measured at 28 days after boosting, with a GMT ratio of 1·43 (95% CI 1·26-1·63). Seroresponse rates were 65·2% (95% CI 60·2-69·9) in the ARCT-154 group versus 51·6% (46·4-56·8) in the BNT162b2 group, a difference of 13·6% (95% CI 6·8-20·5). GMTs against the omicron BA.4/5 variant on day 29 were 2551 (1687-3859) in the ARCT-154 group and 1958 (1281-2993) in the BNT162b2 group-a GMT ratio of 1·30 (1·07-1·58)-with seroresponse rates of 69·9% (65·0-74·4) and 58·0% (52·8-63·1). Both boosters were equally well tolerated. No treatment-related deaths were reported, nor were there severe or serious adverse events considered to be causally associated related to study vaccination. One serious adverse event, a foot deformity reported in a participant in the BNT162b2 group, was observed but determined not to have a causal relationship to the study vaccination. One severe adverse event, a case of abnormal hepatic function in the ARCT-154 group, was considered to be related to study vaccine. Adverse events of special interest for detection of myocarditis and pericarditis included chest pain (one case in the ARCT-154 group and three cases in the BNT162b2 group) and shortness of breath (two cases in the BNT162b2 group), all of which were considered to have a reasonable possibility of being related to vaccination. Local reactions were reported by 398 (95%) of 420 participants receiving the ARCT-154 vaccine and 395 (97%) of 408 participants receiving the BNT162b2 vaccine, and solicited systemic adverse events by 276 (66%) of those receiving the ARCT-154 vaccine and 255 (63%) of those receiving the BNT162b2 vaccine. Adverse events were mainly mild in severity, occurring and resolving within 3-4 days after vaccination.

INTERPRETATION

In adults who had previously received three doses of an mRNA COVID-19 vaccine, immune responses 28 days after an ARCT-154 booster dose were non-inferior to those observed after a BNT162b2 booster dose for the Wuhan-Hu-1 strain of SARS-CoV-2 and superior for the Omicron BA.4/5 variant. Increased immune responses at 28 days might provide increased likelihood of protection against these strains during this period and could also result in longer duration of protection. Further studies will assess the immunogenicity induced against more recent SARS-CoV-2 variants.

FUNDING

Japanese Ministry of Health, Labour, and Welfare.

TRANSLATION

For the Japanese translation of the abstract see Supplementary Materials section.

Population-Based Evaluation of Vaccine Effectiveness against SARS-CoV-2 Infection, Severe Illness, and Death, Taiwan

Taiwan provided several COVID-19 vaccine platforms: mRNA (BNT162b2, mRNA-1273), adenoviral vector-based (AZD1222), and protein subunit (MVC-COV1901). After Taiwan shifted from its zero-COVID strategy in April 2022, population-based evaluation of vaccine effectiveness (VE) became possible. We conducted an observational cohort study of 21,416,151 persons to examine VE against SARS-CoV-2 infection, moderate and severe illness, and death during March 22, 2021-September 30, 2022. After adjusting for age and sex, we found that persons who completed 3 vaccine doses (2 primary, 1 booster) or received MVC-COV1901 as the primary series had the lowest hospitalization incidence (0.04-0.20 cases/100,000 person-days). We also found 95.8% VE against hospitalization for 3 doses of BNT162b2, 91.0% for MVC-COV1901, 81.8% for mRNA-1273, and 65.7% for AZD1222, which had the lowest overall VE. Our findings indicated that protein subunit vaccines provide similar protection against SARS-CoV-2---associated hospitalization as mRNA vaccines and can inform mix-and-match vaccine selection in other countries.

Temporal changes in factors associated with COVID-19 vaccine hesitancy among Chinese adults: Repeated nationally representative survey

Background

COVID-19 vaccine hesitancy has been cited as one of the main obstacles impacting vaccine coverage. However, factors that affect hesitancy may change over time. Understanding these evolving concerns and adapting strategies accordingly are crucial for effectively addressing vaccine hesitancy effectively and promoting public health. We aimed to explore the temporal changes in factors associated with COVID-19 VH during the COVID-19 pandemic and assess the dynamic evolution of VH.

Methods

In August 2022 and February 2023, repeated online surveys were undertaken to collect information from 5378 adults across four regions of China. Multiple linear regression models assessed the influencing factors of COVID-19 VH. The association between protective motive theory (PMT) (perceived severity, susceptibility, benefits, barriers, and self-efficacy) and VH was evaluated by structural equation modeling (SEM).

Results

Repeated measures showed that 573 (10.7%) and 1598 (29.7%) of the 5378 participants reported COVID-19 VH in the baseline and follow-up surveys, respectively. Educational levels, chronic disease, history of allergy, COVID-19 infection, and trust in medical staff and vaccine developers were positively associated with COVID-19 VH (P＜0.05). The application of SEM revealed that perceived severity, susceptibility, vaccination barriers, and self-efficacy in the PMT directly impacted on VH (P＜0.05). In addition, severity, susceptibility, benefits, and barriers had a significant direct effect on self-efficacy as β = 0.113, β = 0.070, β = 0.722, β = -0.516 respectively with P < 0.001.

Conclusion

The prevalence of COVID-19 VH was relatively low in the baseline survey and much higher in the follow-up survey, with a significant increase in hesitancy rates among mainland Chinese residents. Acknowledging the substantial impact on the shaping of COVID-19 VH, one must consider factors including perceived severity, susceptibility, vaccination barriers, and self-efficacy.

Building the U.S. COVID-19 vaccine effectiveness program: Past successes and future directions

COVID-19 vaccines were originally authorized in the United States in December 2020 on the basis of safety, immunogenicity, and clinical efficacy data from randomized controlled trials (RCTs). However, real-world vaccine effectiveness (VE) data are necessary to provide information on how the vaccines work in populations not included in the RCTs (e.g., nursing home residents), against new SARS-CoV-2 variants, with increasing time since vaccination, and in populations with increasing levels of prior infection. The goal of CDC's COVID-19 VE program is to provide timely and robust data to support ongoing policy decisions and implementation of vaccination and includes VE platforms to study the spectrum of illness, from infection to critical illness. Challenges to estimating VE include accurate ascertainment of vaccination history, outcome status, changing rates of prior infection, emergence of new variants, and appropriate interpretation of absolute and relative VE measures. CDC COVID-19 VE platforms have played a pivotal role in numerous vaccine policy decisions since 2021 and will continue to play a key role in future decisions as the vaccine program moves from an emergency response to a routine schedule.

Protection of the third-dose and fourth-dose mRNA vaccines against SARS-CoV-2 Omicron subvariant: a systematic review and meta-analysis

OBJECTIVES

The rapid spread of the SARS-CoV-2 Omicron variant has raised concerns regarding waning vaccine-induced immunity and durability. We evaluated protection of the third-dose and fourth-dose mRNA vaccines against SARS-CoV-2 Omicron subvariant and its sublineages.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Electronic databases and other resources (PubMed, Embase, CENTRAL, MEDLINE, CINAHL PLUS, APA PsycINFO, Web of Science, Scopus, ScienceDirect, MedRxiv and bioRxiv) were searched until December 2022.

STUDY ELIGIBILITY CRITERIA

We included studies that assessed the effectiveness of mRNA vaccine booster doses against SARS-CoV-2 infection and severe COVID-19 outcomes caused by the subvariant.

DATA EXTRACTION AND SYNTHESIS

Estimates of vaccine effectiveness (VE) at different time points after the third-dose and fourth-dose vaccination were extracted. Random-effects meta-analysis was used to compare VE of the third dose versus the primary series, no vaccination and the fourth dose at different time points. The certainty of the evidence was assessed by Grading of Recommendations, Assessments, Development and Evaluation approach.

RESULTS

This review included 50 studies. The third-dose VE, compared with the primary series, against SARS-CoV-2 infection was 48.86% (95% CI 44.90% to 52.82%, low certainty) at ≥14 days, and gradually decreased to 38.01% (95% CI 13.90% to 62.13%, very low certainty) at ≥90 days after the third-dose vaccination. The fourth-dose VE peaked at 14-30 days (56.70% (95% CI 50.36% to 63.04%), moderate certainty), then quickly declined at 61-90 days (22% (95% CI 6.40% to 37.60%), low certainty). Compared with no vaccination, the third-dose VE was 75.84% (95% CI 40.56% to 111.12%, low certainty) against BA.1 infection, and 70.41% (95% CI 49.94% to 90.88%, low certainty) against BA.2 infection at ≥7 days after the third-dose vaccination. The third-dose VE against hospitalisation remained stable over time and maintained 79.30% (95% CI 58.65% to 99.94%, moderate certainty) at 91-120 days. The fourth-dose VE up to 60 days was 67.54% (95% CI 59.76% to 75.33%, moderate certainty) for hospitalisation and 77.88% (95% CI 72.55% to 83.21%, moderate certainty) for death.

CONCLUSION

The boosters provided substantial protection against severe COVID-19 outcomes for at least 6 months, although the duration of protection remains uncertain, suggesting the need for a booster dose within 6 months of the third-dose or fourth-dose vaccination. However, the certainty of evidence in our VE estimates varied from very low to moderate, indicating significant heterogeneity among studies that should be considered when interpreting the findings for public health policies.

PROSPERO REGISTRATION NUMBER

CRD42023376698.

Identifying beliefs driving COVID-19 vaccination: Lessons for effective messaging

Increasing vaccination acceptance has been essential during the COVID-19 pandemic and in preparation for future public health emergencies. This study aimed to identify messaging strategies to encourage vaccine uptake by measuring the drivers of COVID-19 vaccination among the general public. A survey to assess COVID-19 vaccination acceptance and hesitancy was advertised on Facebook in February-April 2022. The survey included items asking about COVID-19 vaccination status and participant demographics, and three scales assessing medical mistrust, perceived COVID-19 risk, and COVID-19 vaccine confidence (adapted from the Oxford COVID-19 vaccine confidence and complacency scale). The main outcome was vaccination, predicted by patient demographics and survey scale scores. Of 1,915 survey responses, 1,450 (75.7%) were included, with 1,048 (72.3%) respondents reporting they had been vaccinated. In a multivariable regression model, the COVID-19 vaccine confidence scale was the strongest predictor of vaccination, along with education level and perceived COVID-19 risk. Among the items on this scale, not all were equally important in predicting COVID-19 vaccination. The items that best predicted vaccination, at a given score on the COVID-19 vaccine confidence scale, included confidence that vaccine side effects are minimal, that the vaccine will work, that the vaccine will help the community, and that the vaccine provides freedom to move on with life. This study improved our understanding of perceptions most strongly associated with vaccine acceptance, allowing us to consider how to develop messages that may be particularly effective in encouraging vaccination among the general public for both the COVID-19 pandemic and future public health emergencies.

Multiantigen pan-sarbecovirus DNA vaccines generate protective T cell immune responses

SARS-CoV-2 is the third zoonotic coronavirus to cause a major outbreak in humans in recent years, and many more SARS-like coronaviruses with pandemic potential are circulating in several animal species. Vaccines inducing T cell immunity against broadly conserved viral antigens may protect against hospitalization and death caused by outbreaks of such viruses. We report the design and preclinical testing of 2 T cell-based pan-sarbecovirus vaccines, based on conserved regions within viral proteins of sarbecovirus isolates of human and other carrier animals, like bats and pangolins. One vaccine (CoVAX_ORF1ab) encoded antigens derived from nonstructural proteins, and the other (CoVAX_MNS) encoded antigens from structural proteins. Both multiantigen DNA vaccines contained a large set of antigens shared across sarbecoviruses and were rich in predicted and experimentally validated human T cell epitopes. In mice, the multiantigen vaccines generated both CD8+ and CD4+ T cell responses to shared epitopes. Upon encounter of full-length spike antigen, CoVAX_MNS-induced CD4+ T cells were responsible for accelerated CD8+ T cell and IgG Ab responses specific to the incoming spike, irrespective of its sarbecovirus origin. Finally, both vaccines elicited partial protection against a lethal SARS-CoV-2 challenge in human angiotensin-converting enzyme 2-transgenic mice. These results support clinical testing of these universal sarbecovirus vaccines for pandemic preparedness.

Vaccine Preventable Disease and Vaccine Hesitancy

Global immunization programs have saved tens of millions of lives over the last 2 decades. Now, the recent successes of COVID-19 vaccines having saved more than 3 million lives in North America during the pandemic may open the door to accelerate technologies for other emerging infection vaccines. New vaccines for respiratory syncytial virus, norovirus, influenza, herpes simplex virus, shingles, dengue fever, enteric bacterial infections, malaria, and Chagas disease are advancing through clinical development and could become ready for delivery over the next 5 years. The successful delivery of these new vaccines may require expanded advocacy and communications efforts.

Protection of COVID-19 Vaccination Against Hospitalization During the Era of Omicron BA.4 and BA.5 Predominance: A Nationwide Case-Control Study Based on the French National Health Data System

Background

Knowing the duration of effectiveness of coronavirus disease 2019 (COVID-19) booster doses is essential to providing decision-makers with scientific arguments about the frequency of subsequent injections. We estimated the level of protection against COVID-19-related hospitalizations (Omicron BA.4-BA.5) over time after vaccination, accounting for breakthrough infections.

Methods

In this nationwide case-control study, all cases of hospitalizations for COVID-19 identified in the comprehensive French National Health Data System between June 1, 2022, and October 15, 2022, were matched with up to 10 controls by year of birth, sex, department, and an individual COVID-19 hospitalization risk score. Conditional logistic regressions were used to estimate the level of protection against COVID-19-related hospitalizations conferred by primary and booster vaccination, accounting for history of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

Results

A total of 38 839 cases were matched to 377 653 controls; 19.2% and 9.9% were unvaccinated, respectively, while 68.2% and 77.7% had received ≥1 booster dose. Protection provided by primary vaccination reached 45% (95% CI, 42%-47%). The incremental effectiveness of booster doses ranged from 69% (95% CI, 67%-71%; ≤2 months) to 22% (95% CI, 19%-25%; ≥6 months). Specifically, the second booster provided an additional protection compared with the first ranging from 61% (95% CI, 59%-64%; ≤2 months) to 7% (95% CI, 2%-13%; ≥4 months). Previous SARS-CoV-2 infection conferred a strong, long-lasting protection (51% ≥20 months). There was no incremental effectiveness of a second booster among individuals infected since the first booster.

Conclusions

In the era of Omicron BA.4 and BA.5 predominance, primary vaccination still conferred protection against COVID-19 hospitalization, while booster doses provided an additional time-limited protection. The second booster had no additional protection in case of infection since the first booster.

Safety and immunogenicity of a modified Omicron-adapted inactivated vaccine in healthy adults: a randomized, double-blind, active-controlled Phase III clinical trial

Background

Updated vaccine strategies are needed to protect against new SARS-CoV-2 variants with increased immune escape. Here, information on the safety and immunogenicity of an inactivated Omicron-adapted vaccine is presented, as compared with CoronaVac.

Methods

A randomized, double-blind, active-controlled, phase III clinical trial was conducted to compare a modified Omicron-adapted vaccine (Omicron vaccine) with the authorized prototype vaccine (CoronaVac®) as a booster dose. Healthy adults aged ≥18 years, who have previously received 2 or 3 doses of CoronaVac (2C or 3C cohort) at least 6 months before, were enrolled to get a booster dose of Omicron vaccine or CoronaVac in a ratio of 2:1 (2C/3C+1O/1C). Back-up serums after two initial doses of CoronaVac (2C+0) for adults aged 26-45 years were collected from a previous study. Immunogenicity and safety data at 28 days after vaccination were collected and analyzed. One of the primary objectives was to evaluate the superiority of immunogenicity of Omicron vaccine booster against Omicron BA.1, compared with CoronaVac booster against BA.1. Another objective was to evaluate the non-inferiority of immunogenicity of Omicron vaccine booster against BA.1, compared with two initial doses of CoronaVac against ancestral strain.

Results

Between June 1st and July 21st, 2022, a total of 1,500 healthy adults were enrolled. Results show that all pre-specified superiority criteria for BA.1 neutralizing antibody were met. Specifically, within the 3C cohort (3C+1O vs. 3C+1C), the geometric mean titers' (GMT) ratio and 95% confidence interval (CI) was 1.64 (1.42, 1.89), with the lower 95%CI ≥1; a GMT ratio of 1.84 (1.57, 2.16) was observed for 2C+1O versus 3C+1C. For seroconversion rate, the lower 95%CIs of differences between immuno-comparative groups (2/3C+1O vs. 3C+1C) were all above the superiority criterion 0%. However, the non-inferiority criterion of the lower 95%CI of GMT ratio ≥2/3 was unfulfilled for 2C/3C+1O against BA.1 versus 2C+0 against ancestral strain. Safety profiles were similar between groups, with no safety concerns identified.

Conclusion

The Omicron-adapted vaccine was well-tolerated and could elicit superior immune responses as compared with CoronaVac against Omicron, while it appeared inferior to CoronaVac against ancestral strain.

Clinical trial registration

https://classic.clinicaltrials.gov/ct2/show/NCT05381350?term=NCT05381350&draw=2&rank=1, identifier NCT05381350.

Comparative effectiveness of four COVID-19 vaccines, BNT162b2 mRNA, mRNA-1273, ChAdOx1 nCov-19 and NVX-CoV2373 against SARS-CoV-2 B.1.1.529 (Omicron) infection

BACKGROUND

There is limited data directly comparing the effectiveness of different COVID-19 vaccines.

METHODS

We compared rates of SARS-CoV-2 Omicron BA.1/2 infection during March to May 2022 in Australian adults who had received one of four COVID-19 vaccines in the last 14-63 days as either a primary course or a booster dose using Cox proportional hazards models adjusting for age and other characteristics.

RESULTS

As a primary course, over 2318 person-years and 1033 infections, compared to recipients of BNT162b2 mRNA vaccine, adjusted hazard ratios for SARS-CoV-2 infection were 1.03 (95%CI 0.82-1.30), 1.19 (0.95-1.49), 1.70 (1.46-1.97) for respectively mRNA-1273, ChAdOx-1 nCov-19 and NVX-CoV2373. For the booster dose, over 154,984 person-years and 93,580 infections the respective adjusted hazard ratios compared to BNT162b2 mRNA vaccine were 1.02 (95%CI 1.00-1.04), 1.20 (1.10-1.32), 1.39 (1.20-1.60).

CONCLUSIONS

Our findings suggest relatively higher effectiveness of ancestral strain mRNA vaccines against SARS-CoV-2 Omicron infection than viral vector and protein subunit vaccines and provide clinical confirmation of immunological data on differences in COVID-19 vaccine performance.

Social participation during the COVID-19 pandemic in persons with a high risk for a severe course of COVID-19 - results of a longitudinal, multi-center observational study in Germany

Objective

The COVID-19 pandemic has affected how people go about their daily lives, often in various and substantial ways. This study aims to prospectively evaluate the changes in social participation during the COVID-19 pandemic in persons with a high risk for a severe COVID-19 course in Germany.

Methods

A paper-pencil-based survey was conducted starting at March 2021. Participants filled out questionnaires at four time points based on their COVID-19 vaccination status: before COVID-19 vaccination, one month, six months and twelve months after COVID-19 vaccination. Social participation measures included the Pandemic Social Participation Questionnaire (PSP-Q) and the Index for measuring participation restrictions (IMET). Repeated measures ANOVA and paired t-test were used to test for changes between time-points. Repeated measures correlation was used to assess the relationship between social participation and local COVID-19 incidences.

Results

Data from 245 participants was analyzed before and one month after COVID-19 vaccination. In addition, data from 156 participants was analyzed at time points one, six and twelve months after COVID-19. PSP-Q and IMET scores changed significantly after participants received a COVID-19 vaccination. Between one month and twelve months after vaccination, social participation improved significantly measured by PSP-Q. Social participation was negatively correlated with regional COVID-19 incidences before and after COVID-19 vaccination. Social participation was positively correlated with COVID-19 incidences between one month and twelve months after COVID-19 vaccination.

Conclusions

Social participation improved in persons with a high risk for a severe COVID-19 course during the pandemic. The local COVID-19 incidence showed a negative association with social participation only until the fall of 2021 when it was used as the sole metric to regulate COVID-19 protective measures. Although our data describes the trends in social participation, further studies are needed to identify the influencing factors for the observed increase in social participation.

Total and Subgenomic RNA Viral Load in Patients Infected With SARS-CoV-2 Alpha, Delta, and Omicron Variants

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomic and subgenomic RNA levels are frequently used as a correlate of infectiousness. The impact of host factors and SARS-CoV-2 lineage on RNA viral load is unclear.

METHODS

Total nucleocapsid (N) and subgenomic N (sgN) RNA levels were measured by quantitative reverse transcription polymerase chain reaction (RT-qPCR) in specimens from 3204 individuals hospitalized with coronavirus disease 2019 (COVID-19) at 21 hospitals. RT-qPCR cycle threshold (Ct) values were used to estimate RNA viral load. The impact of time of sampling, SARS-CoV-2 variant, age, comorbidities, vaccination, and immune status on N and sgN Ct values were evaluated using multiple linear regression.

RESULTS

Mean Ct values at presentation for N were 24.14 (SD 4.53) for non-variants of concern, 25.15 (SD 4.33) for Alpha, 25.31 (SD 4.50) for Delta, and 26.26 (SD 4.42) for Omicron. N and sgN RNA levels varied with time since symptom onset and infecting variant but not with age, comorbidity, immune status, or vaccination. When normalized to total N RNA, sgN levels were similar across all variants.

CONCLUSIONS

RNA viral loads were similar among hospitalized adults, irrespective of infecting variant and known risk factors for severe COVID-19. Total N and subgenomic RNA N viral loads were highly correlated, suggesting that subgenomic RNA measurements add little information for the purposes of estimating infectivity.

Dynamic Trends and Underlying Factors of COVID-19 Vaccine Booster Hesitancy in Adults: Cross-Sectional Observational Study

BACKGROUND

COVID-19 vaccine hesitancy reduces vaccination rates, which is detrimental to building herd immunity and halting the spread of COVID-19 and its variations. Most researches have simply identified the reasons affecting COVID-19 vaccination reluctance without delving into its dynamics, which makes forecasting future trends difficult.

OBJECTIVE

This study aimed to examine the current COVID-19 vaccine booster hesitancy rate in Chinese adults as well as the dynamics of vaccine hesitancy and its influencing factors. The results of this study will have practical implications for policy responses in mainland China, and effective COVID-19 booster vaccination in specific populations.

METHODS

The web-based survey was completed by creating questionnaires and using a stratified random sampling method to collect information from adults (≥18 years old) among 2556 households in 4 geographical regions of China. We collected sociodemographic information, health status, awareness of COVID-19 and its vaccine, self-perceptions, trust in medical staff and vaccine developers, and so on. The odds ratios and 95% CI for the statistical associations were estimated using logistic regression models.

RESULTS

Overall, 6659 participants (females: n=3540, 53.2%; males: n=3119, 46.8%) responded. In total, 533 (8%; 95% CI 7.4%-8.7%) participants presented a clear hesitancy in receiving the COVID-19 booster vaccination, while 736 (11.1%; 95% CI 10.3%-11.8%) expressed hesitancy in regular booster vaccination. A higher prevalence of vaccine hesitancy in both booster vaccination and regular booster vaccination was observed among participants with a history of allergies, experiencing chronic disease, lower levels of public health prevention measures or susceptibility or benefits or self-efficiency, higher levels of severity or barriers, and lower trust in both medical staff and vaccine developers (P<.05). The females and participants with higher education levels, higher levels of barriers, lower levels of susceptibility, and lower trust in vaccine developers preferred to have attitudinal changes from acceptance to hesitancy, while people with higher education levels, lower self-report health conditions, experiencing chronic disease, history of allergies, and lower trust in medical staff and developers were all positively associated with constant COVID-19 booster hesitancy.

CONCLUSIONS

The prevalence of COVID-19 vaccine booster hesitancy is not high in mainland China. However, there is a slight increment in hesitancy on regular booster vaccination. Conducting targeted information guidance for people with higher education levels and chronic diseases, as well as improving accessibility to booster vaccination and increasing trust in medical staff and vaccine producers may be highly effective in reducing vaccine hesitancy.

Immunogenicity and reactogenicity of inactivated SARS-CoV-2 vaccines in healthy adults

Introduction

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly pathogenic to humans and has caused the ongoing coronavirus disease 2019 (COVID-19) pandemic. Vaccines are one of the efficient ways to prevent the viral infection. After COVID-19 vaccination, the monitoring of the dynamic change in neutralizing antibodies is necessary to determine booster requirements.

Methods

We estimated the effectiveness of the inactivated vaccines by monitoring dynamic SARS-CoV-2 neutralizing antibodies for over 2 years. Additionally, we also investigated the activation of T lymphocytes (CD3+ T cells) after three doses of the inactivated vaccine.

Result

The results showed that the rate of reduction of SARS-CoV-2 neutralizing antibody levels gradually showed after each booster dose. The IgG/IgM level at 9 months after the third vaccination were significantly higher than those at 6 months after the second dose (p<0.0001). The expression of CD25+T cell in 18-35 age group was significantly higher than that in the other groups. Nine months after the third dose (the time of last blood sample collection), the expression of CD25+T cell in the 18-35 age group was significantly higher than that at 6 months after the second dose. CD25+T cell in the 18-35 years old group was significantly higher than 6 months after the second vaccination.

Conclusion

CD25, a late activation marker of lymphocytes and high-activity memory T cell subgroup, exhibited higher levels at the later stages after vaccination. COVID-19 booster vaccination in older adults and regular testing of SARS-CoV-2 neutralizing antibodies are recommended. Booster doses should be administered if the antibody level falls below the 30% inhibition rate.

Safety and immunogenicity of a tetravalent and bivalent SARS-CoV-2 protein booster vaccine in men

The safety and immunogenicity of a protein-based tetravalent vaccine SCTV01E that contains spike protein ectodomain (S-ECD) of Alpha, Beta, Delta and Omicron BA.1 are assessed and compared with bivalent protein vaccine SCTV01C (Alpha and Beta variants) and monovalent mRNA vaccine (NCT05323461). The primary endpoints are the geometric mean titers (GMT) of live virus neutralizing antibodies (nAb) to Delta (B.1.617.2) and Omicron BA.1 at day 28 post-injection. The secondary endpoints include the safety, day 180 GMTs against Delta and Omicron BA.1, day 28 GMTs to BA.5, and seroresponse rates of neutralizing antibodies and T cell responses at day 28 post-injection. 450 participants, comprising of 449 males and 1 female, with a median age (range) of 27 (18-62) years, are assigned to receive one booster dose of BNT162b2, 20 µg SCTV01C or 30 µg SCTV01E and completed 4-week follow-up. All SCTV01E related adverse events (AEs) are mild or moderate and no Grade ≥3 AE, serious AE or new safety concerns are identified. Day 28 GMT of live virus neutralizing antibodies and seroresponse against Omicron BA.1 and BA.5 with SCTV01E are significantly higher than those with SCTV01C and BNT162b2. These data indicate an overall neutralization superiority with tetravalent booster immunization in men.

Effectiveness of SARS-CoV-2 vaccines against Omicron infection and severe events: a systematic review and meta-analysis of test-negative design studies

Background

A rapidly growing body was observed of literature evaluating the vaccine effectiveness (VE) against Omicron in test-negative design studies.

Methods

We systematically searched papers that evaluated VE of SARS-CoV-2 vaccines on PubMed, Web of Science, Cochrane Library, Google Scholar, Embase, Scopus, bioRxiv, and medRxiv published from November 26th, 2021, to June 27th, 2022 (full doses and the first booster), and to January 8th, 2023 (the second booster). The pooled VE against Omicron-associated infection and severe events were estimated.

Results

From 2,552 citations identified, 42 articles were included. The first booster provided stronger protection against Omicron than full doses alone, shown by VE estimates of 53.1% (95% CI: 48.0-57.8) vs. 28.6% (95% CI: 18.5-37.4) against infection and 82.5% (95% CI: 77.8-86.2) vs. 57.3% (95% CI: 48.5-64.7) against severe events. The second booster offered strong protection among adults within 60 days of vaccination against infection (VE=53.1%, 95% CI: 48.0-57.8) and severe events (VE=87.3% (95% CI: 75.5-93.4), comparable to the first booster with corresponding VE estimates of 59.9% against infection and 84.8% against severe events. The VE estimates of booster doses against severe events among adults sustained beyond 60 days, 77.6% (95% CI: 69.4-83.6) for first and 85.9% (95% CI: 80.3-89.9) for the second booster. The VE estimates against infection were less sustainable regardless of dose type. Pure mRNA vaccines provided comparable protection to partial mRNA vaccines, but both provided higher protection than non-mRNA vaccines.

Conclusions

One or two SARS-CoV-2 booster doses provide considerable protection against Omicron infection and substantial and sustainable protection against Omicron-induced severe clinical outcomes.

NVX-CoV2373 vaccine efficacy against hospitalization: A post hoc analysis of the PREVENT-19 phase 3, randomized, placebo-controlled trial

PREVENT-19, the pivotal phase 3 trial of the Novavax adjuvanted, recombinant spike protein COVID-19 vaccine (NVX-CoV2373), demonstrated that the vaccine was well tolerated and efficacious (vaccine efficacy, VE = 90%) for the prevention of symptomatic COVID-19. In the trial, participants were randomly assigned in a 2:1 ratio to receive 2 doses of NVX-CoV2373 or placebo 21 days apart. Throughout the study, the predominant SARS-CoV-2 variant was alpha, but additional variants were in circulation (i.e., beta, gamma, epsilon, and iota). VE among the per-protocol efficacy analysis population was calculated according to pre-specified disease severity (mild, moderate, or severe) criteria, but the impact on the risk of COVID-19-associated hospitalization was not specifically investigated. During this analysis period (January 25, 2021, to April 30, 2021 [95 days]), 4 hospitalizations occurred among the 77 events analyzed for the primary endpoint using the per-protocol population, 0 among vaccine recipients and 4 among placebo recipients, yielding a post hoc VE against hospitalization of 100% (95% CI: 28.8, 100). Among an expanded efficacy population, also identified post hoc, which included COVID-19-associated hospitalizations without a requirement for diagnostic polymerase chain reaction testing performed at the study central laboratory, 12 total hospitalizations were identified, 0 among vaccine recipients and 12 among placebo recipients, yielding a post hoc VE against hospitalization of 100% (95% CI: 83.1, 100). These additional data from the PREVENT-19 trial provide relevant public health information concerning the attributes of NVX-CoV2373.

Renin-Angiotensin System Modulation With Synthetic Angiotensin (1-7) and Angiotensin II Type 1 Receptor-Biased Ligand in Adults With COVID-19: Two Randomized Clinical Trials

Importance

Preclinical models suggest dysregulation of the renin-angiotensin system (RAS) caused by SARS-CoV-2 infection may increase the relative activity of angiotensin II compared with angiotensin (1-7) and may be an important contributor to COVID-19 pathophysiology.

Objective

To evaluate the efficacy and safety of RAS modulation using 2 investigational RAS agents, TXA-127 (synthetic angiotensin [1-7]) and TRV-027 (an angiotensin II type 1 receptor-biased ligand), that are hypothesized to potentiate the action of angiotensin (1-7) and mitigate the action of the angiotensin II.

Design, Setting, and Participants

Two randomized clinical trials including adults hospitalized with acute COVID-19 and new-onset hypoxemia were conducted at 35 sites in the US between July 22, 2021, and April 20, 2022; last follow-up visit: July 26, 2022.

Interventions

A 0.5-mg/kg intravenous infusion of TXA-127 once daily for 5 days or placebo. A 12-mg/h continuous intravenous infusion of TRV-027 for 5 days or placebo.

Main Outcomes and Measures

The primary outcome was oxygen-free days, an ordinal outcome that classifies a patient's status at day 28 based on mortality and duration of supplemental oxygen use; an adjusted odds ratio (OR) greater than 1.0 indicated superiority of the RAS agent vs placebo. A key secondary outcome was 28-day all-cause mortality. Safety outcomes included allergic reaction, new kidney replacement therapy, and hypotension.

Results

Both trials met prespecified early stopping criteria for a low probability of efficacy. Of 343 patients in the TXA-127 trial (226 [65.9%] aged 31-64 years, 200 [58.3%] men, 225 [65.6%] White, and 274 [79.9%] not Hispanic), 170 received TXA-127 and 173 received placebo. Of 290 patients in the TRV-027 trial (199 [68.6%] aged 31-64 years, 168 [57.9%] men, 195 [67.2%] White, and 225 [77.6%] not Hispanic), 145 received TRV-027 and 145 received placebo. Compared with placebo, both TXA-127 (unadjusted mean difference, -2.3 [95% CrI, -4.8 to 0.2]; adjusted OR, 0.88 [95% CrI, 0.59 to 1.30]) and TRV-027 (unadjusted mean difference, -2.4 [95% CrI, -5.1 to 0.3]; adjusted OR, 0.74 [95% CrI, 0.48 to 1.13]) resulted in no difference in oxygen-free days. In the TXA-127 trial, 28-day all-cause mortality occurred in 22 of 163 patients (13.5%) in the TXA-127 group vs 22 of 166 patients (13.3%) in the placebo group (adjusted OR, 0.83 [95% CrI, 0.41 to 1.66]). In the TRV-027 trial, 28-day all-cause mortality occurred in 29 of 141 patients (20.6%) in the TRV-027 group vs 18 of 140 patients (12.9%) in the placebo group (adjusted OR, 1.52 [95% CrI, 0.75 to 3.08]). The frequency of the safety outcomes was similar with either TXA-127 or TRV-027 vs placebo.

Conclusions and Relevance

In adults with severe COVID-19, RAS modulation (TXA-127 or TRV-027) did not improve oxygen-free days vs placebo. These results do not support the hypotheses that pharmacological interventions that selectively block the angiotensin II type 1 receptor or increase angiotensin (1-7) improve outcomes for patients with severe COVID-19.

Trial Registration

ClinicalTrials.gov Identifier: NCT04924660.

Retrospective Analysis of Vaccination Status and Predominant Viral Variants in Patients Hospitalized with COVID-19 in Reus, Spain

SARS-CoV-2 infection in already-vaccinated individuals is still possible and may require hospitalization. The aim of the present study was to evaluate the clinical evolution of patients with COVID-19 admitted to a public hospital. The outcomes were assessed in relation to the predominant viral variant and the vaccination status. This retrospective study was performed on 1295 COVID-19-positive patients who attended a 352-bed university hospital between 2021 and 2022. Clinical variables and vaccination status were recorded. Of the patients, 799 had not been vaccinated (NV, 61.7%), 449 were partially vaccinated (PV, 34.7%), and 47 were completely vaccinated (CV, 3.6%). The mean age of the CV patients was significantly higher than that of PV and NV. Additionally, they had higher percentages of chronic diseases. The outcomes depended on age but not on vaccination status. There were 209 patients admitted during the Omicron-infection period, of whom 70 (33.5%) were NV, 135 (64.6%) were PV, and 4 (1.9%) were CV. In conclusion, correct vaccination greatly reduces the risk of acquiring severe COVID-19. Partial vaccination does not guarantee protection of the population. This highlights the need for continuous vaccination promotion with all recommended doses, while also investigating alternative treatments for those patients who do not respond to the vaccines.

Vaccine Effectiveness Against Influenza A(H3N2)-Associated Hospitalized Illness: United States, 2022

BACKGROUND

The COVID-19 pandemic was associated with historically low influenza circulation during the 2020-2021 season, followed by an increase in influenza circulation during the 2021-2022 US season. The 2a.2 subgroup of the influenza A(H3N2) 3C.2a1b subclade that predominated was antigenically different from the vaccine strain.

METHODS

To understand the effectiveness of the 2021-2022 vaccine against hospitalized influenza illness, a multistate sentinel surveillance network enrolled adults aged ≥18 years hospitalized with acute respiratory illness and tested for influenza by a molecular assay. Using the test-negative design, vaccine effectiveness (VE) was measured by comparing the odds of current-season influenza vaccination in influenza-positive case-patients and influenza-negative, SARS-CoV-2-negative controls, adjusting for confounders. A separate analysis was performed to illustrate bias introduced by including SARS-CoV-2-positive controls.

RESULTS

A total of 2334 patients, including 295 influenza cases (47% vaccinated), 1175 influenza- and SARS-CoV-2-negative controls (53% vaccinated), and 864 influenza-negative and SARS-CoV-2-positive controls (49% vaccinated), were analyzed. Influenza VE was 26% (95% CI: -14% to 52%) among adults aged 18-64 years, -3% (-54% to 31%) among adults aged ≥65 years, and 50% (15-71%) among adults aged 18-64 years without immunocompromising conditions. Estimated VE decreased with inclusion of SARS-CoV-2-positive controls.

CONCLUSIONS

During a season where influenza A(H3N2) was antigenically different from the vaccine virus, vaccination was associated with a reduced risk of influenza hospitalization in younger immunocompetent adults. However, vaccination did not provide protection in adults ≥65 years of age. Improvements in vaccines, antivirals, and prevention strategies are warranted.

Vaccine-induced or hybrid immunity and COVID-19-associated mortality during the Omicron wave

BACKGROUND

It is not yet entirely clear to what extent vaccine-induced or hybrid immunity protects individuals in Germany from death during the omicron wave of the COVID-19 pandemic.

METHODS

In this retrospective study, we evaluated 470 159 cases over age 59 in the German federal state of Bavaria who tested positive for SARS-CoV-2 between 1 January and 30 June 2022. Cox models were used to estimate adjusted hazard ratios (aHR) for dying within 60 days of the infection, depending on sex, age, time point of infection, and a range of immunity levels.

RESULTS

Over the period of observation, 3836 COVID-19-associated deaths were registered (case fatality rate 0.82 %). Risk of death was significantly lower in cases with a higher immunity level than in unvaccinated cases (aHR for a full primary immunity level, if reached less than six months before the time of the infection: 0.30, 95 %-confidence interval [0.23; 0.39]; if reached more than six months before: aHR 0.46 [0.35; 0.60]). A boosted immunity level lowered risk of death even further (if reached less than three months before the infection: aHR 0.17 [0.15; 0.20]; if reached more than three months before: aHR 0.25 [0.21; 0.29]).

CONCLUSION

Among elderly persons in Bavaria, a higher immunity level was associated with a substantial degree of protection against death during the Omicron wave; the strength of protection may have diminished somewhat over time.

The Fourth Dose of mRNA COVID-19 Vaccine Following 12 Different Three-Dose Regimens: Safety and Immunogenicity to Omicron BA.4/BA.5

The aim of this study is to investigate the reactogenicity and immunogenicity of the fourth dose using monovalent mRNA vaccines after different three-dose regimens and to compare the 30 µg BNT162b2 and 50 µg mRNA-1273 vaccines. This prospective cohort study was conducted between June and October 2022. The self-recorded reactogenicity was evaluated on the subsequent 7 days after a fourth dose. The binding and neutralizing activity of antibodies against the Omicron BA.4/5 variants were determined. Overall, 292 healthy adults were enrolled and received BNT162b2 or mRNA-1273. Reactogenicity was mild to moderate and well tolerated after a few days. Sixty-five individuals were excluded. Thus, 227 eligible individuals received a fourth booster dose of BNT162b2 (n = 109) and mRNA-1273 (n = 118). Most participants, regardless of the type of previous three-dose regimens, elicited a significantly high level of binding antibodies and neutralizing activity against Omicron BA.4/5 28 days after a fourth dose. The neutralizing activity against Omicron BA.4/5 between the BNT162b2 (82.8%) and mRNA-1273 (84.2%) groups was comparable with a median ratio of 1.02. This study found that the BNT162b2 and mRNA-1273 vaccines can be used as a fourth booster dose for individuals who were previously immunized with any prior three-dose mix-and-match COVID-19 vaccine regimens.

Real-World Effectiveness of SARS-CoV-2 Vaccine Booster in Hemodialysis Patients with COVID-19 Receiving Molnupiravir

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine booster is one of the most essential strategies against coronavirus disease 2019 (COVID-19) in the era of emerging variants. However, the effectiveness of SARS-CoV-2 vaccine boosters has not much been investigated in hemodialysis (HD) patients receiving oral antiviral agents. In this retrospective study involving 258 HD patients with COVID-19 receiving molnupiravir, we stratified the study cohort according to vaccination status and compared the baseline characteristics and risks of 30-day composite events (COVID-19-related acute care visits, hospitalization, or mortality) among groups. Our analysis demonstrated that the SARS-CoV-2 vaccine boosters markedly decreased the risk of composite events in HD patients (hazard ratio (95% confidence interval), 0.163 (0.063-0.423) for three vs. ≤ two doses of vaccination, p < 0.001; 0.309 (0.115-0.830) for four vs. ≤ two doses of vaccination, p = 0.020). The benefits of vaccine boosters were similar between patients receiving mRNA-based and protein-based boosters and between those with post-booster intervals of ≤ 120 and > 120 days. In conclusion, for HD patients with initially mild or asymptomatic COVID-19 receiving molnupiravir, the benefits of SARS-CoV-2 vaccine boosters are prominent, irrespective of booster vaccine types.

Not Getting Vaccinated? It Is a Matter of Problem-Solving Abilities and Socio-Cognitive Polarization

The anti-COVID-19 vaccination campaign in the United States provided a significant contribution to the control of the virus spread. Despite the recommendations by public health institutions, vaccine skepticism and hesitancy contributed to low vaccine uptake, thus possibly disrupting the management of preventable diseases associated with the COVID-19 infection. The process that led individuals to accept COVID-19 vaccines required the ability to gather, synthesize, and weigh-up information within a novel, dynamically changing, complex, and ambiguous context. To deal with such complexity, we hypothesized that both the ability of reflection and flexible adaptation played a fundamental role. Based on previous research on cognitive predictors of vaccine refusal, we decided to investigate the combined role of two constructs, namely, problem-solving skills and socio-cognitive polarization (SCP), on vaccine acceptance and uptake. Two-hundred-seventy-seven US participants completed an online survey aimed to measure problem-solving ability, through a rebus puzzles task, and SCP, through a composite measure of absolutist thinking, political conservatism, and xenophobia. Mediation analyses indicated that SCP mediated the association between problem-solving ability and vaccine acceptance, so lower problem-solving abilities associated with higher polarization predicted vaccine rejection. Thus, our findings suggested that low problem-solving skills may represent a risk factor for COVID-19 vaccine refusal, with cognitive and social rigidity playing a crucial role in undermining the anti-COVID-19 vaccine uptake.

Efficacy of a bivalent (D614 + B.1.351) SARS-CoV-2 Protein Vaccine

Background

COVID-19 vaccines with alternative strain compositions are needed to provide broad protection against newly emergent SARS-CoV-2 variants of concern.

Methods

We conducted a global Phase 3, multi-stage efficacy study (NCT04904549) among adults aged ≥18 years. Participants were randomized 1:1 to receive two intramuscular injections 21 days apart of a bivalent SARS-CoV-2 recombinant protein vaccine with AS03-adjuvant (5 μg of ancestral (D614) and 5 μg of B.1.351 [beta] variant spike protein) or placebo. Symptomatic COVID-19 was defined as laboratory-confirmed COVID-19 with COVID-19-like illness (CLI) symptoms. The primary efficacy endpoint was the prevention of symptomatic COVID-19 ≥14 days after the second injection (post-dose 2 [PD2]).

Results

Between 19 Oct 2021 and 15 Feb 2022, 12,924 participants received ≥1 study injection. 75% of participants were SARS-CoV-2 non-naïve. 11,416 participants received both study injections (efficacy-evaluable population [vaccine, n=5,736; placebo, n=5,680]). Up to 15 March 2022, 121 symptomatic COVID-19 cases were reported (32 in the vaccine group and 89 in the placebo group) ≥14 days PD2 with a vaccine efficacy (VE) of 64.7% (95% confidence interval [CI] 46.6; 77.2%). VE was 75.1% (95% CI 56.3; 86.6%) in non-naïve and 30.9% (95% CI -39.3; 66.7%) in naïve participants. Viral genome sequencing identified the infecting strain in 68 cases (Omicron [BA.1 and BA.2 subvariants]: 63; Delta: 4; Omicron and Delta: 1). The vaccine was well-tolerated and had an acceptable safety profile.

Conclusions

A bivalent vaccine conferred heterologous protection against symptomatic infection with newly emergent Omicron (BA.1 and BA.2) in non-naïve adults 18-59 years of age.

Characterization of SARS-CoV-2 recombinants and emerging Omicron sublineages

The SARS-CoV-2 Omicron is currently the predominant circulating variant in the COVID-19 pandemic. The dominating Omicron sublineages respond to host immune pressure and develop advantageous mutations or genetic recombination, which result in variants that are more contagious or better at escaping immune responses in response to previous infection or vaccination. Meanwhile, multiple genetic recombination events have been reported in coinfection cases, the majority of which have resulted from the recombination between co-circulating Omicron BA.1 (or BA.1.1) and Delta variant or BA.2. Here, we review the knowledge and characterization of recombination for SARS-CoV-2 at the population level, provide an update on the occurrence of newly circulating Omicron sublineages, and discuss the effectiveness of novel vaccines/therapeutic drugs against the Omicron variant.

Clinical development of variant-adapted BNT162b2 COVID-19 vaccines: the early Omicron era

INTRODUCTION

The Omicron BA.1 variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and subsequent sub-lineages exhibit partial escape from neutralizing antibodies elicited by vaccines containing or encoding wild-type spike protein. In response to the emergence of Omicron sub-lineages, variant-adapted vaccines that contain or encode for Omicron spike protein components have been developed.

AREAS COVERED

This review presents currently available clinical immunogenicity and safety data on Omicron variant-adapted versions of the BNT162b2 messenger RNA (mRNA) vaccine and summarizes the expected mechanism of action, and rationale for development, of these vaccines. In addition, challenges encountered during development and regulatory approval are discussed.

EXPERT OPINION

Omicron-adapted BNT162b2 vaccines provide a wider breadth and potentially more durable protection against Omicron sub-lineages and antigenically aligned variants when compared with the original vaccine. As SARS-CoV-2 continues to evolve, further vaccine updates may be required. To facilitate this, a globally harmonized regulatory process for the transition to updated vaccines is needed. Next-generation vaccine approaches may provide broader protection against future variants.

Considerations in Understanding Vaccine Effectiveness

Although vaccine effectiveness reports are essential to assessing policies on SARS-CoV-2 vaccination, several factors can affect our interpretation of the results. These include the waning of antibodies, the prevailing viral variants at the time of the study, and COVID-19 disease prevalence in the population. Disease prevalence significantly impacts absolute risk reduction and could skew expected efficacy when increased disease prevalence inflates the absolute risk reduction in the face of a constant relative risk reduction. These factors must be considered in the interpretation of vaccine effectiveness to better understand how vaccines can improve disease prevention among the population. We highlight the impact of various factors on vaccine effectiveness.

Effectiveness of COVID-19 Vaccines in Adults with Diabetes Mellitus: A Systematic Review

Persons with diabetes mellitus may have an increased risk of severe illness or death from COVID-19 compared to persons without diabetes. Prior studies indicate that immune response and thus vaccine effectiveness might be lower in persons with diabetes. We aimed to systematically review the effectiveness of COVID-19 vaccines in adults with diabetes. Pubmed, Embase, Web of Science and Cochrane Library were searched for studies that evaluated the effectiveness of COVID-19 vaccines in adults with diabetes, published before 4 March 2022. Risk of bias in the included studies was evaluated using the ROBINS-I tool. At least two reviewers conducted the study selection, data extraction, and risk of bias assessment independently. After screening of 2196 studies, a total of 17 articles were included. Six different COVID-19 vaccines (Ad5-nCoV-S, AZD1222, BNT162b2, CoronaVac, JNJ-78436735, and mRNA-1273) were included in the synthesis. Vaccine effectiveness was reported for SARS-CoV-2 infection, symptomatic COVID-19, hospitalization, and death, and ranged from 24 to 96% in persons with diabetes, and from 33 to 97% in total study populations; effectiveness was generally lower for persons with diabetes. Odds ratios for breakthrough infection or severe COVID-19 ranged from 1.03 to 2.41 in vaccinated persons with diabetes compared to persons without diabetes. Even though the included studies were very heterogeneous, results from the synthesis indicate that effectiveness of COVID-19 vaccines might be lower in persons with diabetes. More research is needed on the comparison of vaccine effectiveness between persons with and without diabetes, and the effectiveness of repeat COVID-19 vaccinations.