Effectiveness of inactivated COVID-19 vaccines against severe illness in B.1.617.2 (Delta) variant-infected patients in Jiangsu, China

Effectiveness of COVID-19 Vaccination against Severe Symptoms and Death Among Geriatric Inpatients: A Retrospective Cohort Study in Macao

Monitoring the effectiveness of COVID-19 vaccination is critical for understanding if the vaccinated population, especially the elderly, is adequately protected from the emergence of new SARS-CoV-2 variants. This study aimed to investigate the effects of COVID-19 vaccination on the severity of symptoms and mortality in hospitalized geriatric patients during the Omicron BF.7 surge in Macao. Data from electronic health records and vaccination registry of inpatients aged 60 years or above admitted to Kiang Wu Hospital from 12 December 2022 to 12 March 2023 were retrospectively analyzed. The study involved 848 people, including 426 vaccinated and 422 unvaccinated individuals. The mean CXR scores (8.95 ± 9.49 vs. 11.41 ± 10.81, p < 0.001) and the mean MEWS scores (0.96 ± 2.01 vs. 1.49 ± 2.45, p < 0.001) were lower in the vaccinated group. By comparing the dose counts, no significant difference was seen in the odds of death. Based on the time of the last vaccination, 128 people were categorized as complete and 298 as incomplete vaccination. The complete vaccination group showed a 54% (95% CI 0.23-0.91) reduction in mortality risk (p = 0.026). The study findings not only reconfirm the effectiveness of COVID-19 vaccination but, more importantly, highlight the importance of vaccination timing to maximize vaccines' protective effect.

Efficacy, immunogenicity, and safety of a monovalent mRNA vaccine, ABO1020, in adults: A randomized, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

ABO1020 is a monovalent COVID-19 mRNA vaccine. Results from a phase 1 trial showed ABO1020 was safe and well tolerated, and phase 3 trials to evaluate the efficacy, immunogenicity, and safety of ABO1020 in healthy adults are urgently needed.

METHODS

We conducted a multinational, randomized, placebo-controlled, double-blind, phase 3 trial among healthy adults (ClinicalTrials.gov: NCT05636319). Participants were randomly assigned (1:1) to receive either 2 doses of ABO1020 (15 μg per dose) or placebo, administered 28 days apart. The primary endpoint was the vaccine efficacy in preventing symptomatic COVID-19 cases that occurred at least 14 days post-full vaccination. The second endpoint included the neutralizing antibody titers against Omicron BA.5 and XBB and safety assessments.

FINDINGS

A total of 14,138 participants were randomly assigned to receive either vaccine or placebo (7,069 participants in each group). A total of 366 symptomatic COVID-19 cases were confirmed 14 days after the second dose among 93 participants in the ABO1020 group and 273 participants in the placebo group, yielding a vaccine efficacy of 66.18% (95% confidence interval: 57.21-73.27, p < 0.0001). A single dose or two doses of ABO1020 elicited potent neutralizing antibodies against both BA.5 and XBB.1.5. The safety profile of ABO1020 was characterized by transient, mild-to-moderate fever, pain at the injection site, and headache.

CONCLUSION

ABO1020 was well tolerated and conferred 66.18% protection against symptomatic COVID-19 in adults.

FUNDING

National Key Research and Development Project of China, Innovation Fund for Medical Sciences from the CAMS, National Natural Science Foundation of China.

Shift in SARS-CoV-2 variants of concern from Delta to Omicron was associated with reduced hospitalizations, increased risk of breakthrough infections but lesser disease severity

BACKGROUND

COVID-19 epidemiology changed with the emergence of SARS-CoV-2 variants of concern (VOC). Pakistan administered mostly inactivated vaccines. We investigated the association between VOC and breakthrough infections in a mixed-vaccination-status population of Karachi.

METHODS

We investigated SARS-CoV-2 VOC tested in 392 respiratory specimens collected between May and December 2021. Data for age, sex, hospital admission, vaccinations, together with CT values of the diagnostic PCR test were analyzed.

RESULTS

The median age of COVID-19 cases tested was 40 (27-57) years and 43.4% were female. Delta variants were most common (56.4%) followed by Alpha (15.9%), Omicron (12.2%), Beta/Gamma (11.3%), and others (4.3%). Eighteen percent of cases were hospitalized whereby, predominant VOC were Beta/Gamma (40.8%), Alpha (35.2%) and Delta (22.5%). Overall, 55.4% of individuals were fully vaccinated, 7.4% were partially vaccinated and 37.2% were unvaccinated. Most (74.6%) inpatients were unvaccinated. Vaccines comprised inactivated (85.34%), single-shot vector (8.62%), two-shot vector (3.02%) and mRNA (3.02%) types. Omicron variants showed lower viral loads as compared to Alpha, Beta/Gamma, and Delta (p = 0.017). The risk of infection with Delta and Omicron variants was higher, 8 weeks after vaccination. The majority of those with breakthrough infections after receiving inactivated vaccines acquired COVID-19 within 4 months of vaccination.

CONCLUSION

Our data highlights the shifting of VOC from Delta to Omicron during 2021 and that COVID-19 vaccinations reduced both hospitalizations and viral transmission. It informs on the increased risk of breakthrough infection within 8 weeks of vaccination, indicating the need for booster vaccinations.

Studying the correlation of inflammatory cytokines to COVID-19 disease

Extreme response of the immune system develops cytokine storm which might be crucial in the pathology of COVID-19. The research aims to evaluate the serum level of IL-6, TNF-α, and IP-10 in severe, mild, and pre-vaccinated one-dose COVID-19 patients and investigate their clinical value and effect in the disease development among different groups of patients. A total of 72 samples were collected 18 as healthy control and 54 from confirmed COVID-19 patients including 18 mild, 18 severe, and 18 pre-vaccinated (one dose). It was confirmed that the severe group of COVID-19 patients had the highest circulating IL-6, TNF- α, and IP-10. IL-6 level in mild and pre-vaccinated (one dose) was significantly lower than in severe. In conclusion, IL-6, TNF-α, and IP-10 are associated with the pathogenicity of COVID-19, furthermore, vaccination could help to control severity of the disease.

Effect of vaccination status on CORADS and computed tomography severity score in hospitalized COVID-19 patients: A retrospective study

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic is continuing. The disease most commonly affects the lungs. Since the beginning of the pandemic thorax computed tomography (CT) has been an indispensable imaging method for diagnosis and follow-up. The disease is tried to be controlled with vaccines. Vaccination reduces the possibility of a severe course of the disease.

AIM

The aim of this study is to investigate whether the vaccination status of patients hospitalized due to COVID-19 has an effect on the CT severity score (CT-SS) and CORADS score obtained during hospitalization.

METHODS

The files of patients hospitalized between April 1, 2021 and April 1, 2022 due to COVID-19 were retrospectively reviewed. A total of 224 patients who were older than 18 years of age, whose vaccination status was accessible, whose severe acute respiratory syndrome coronavirus 2 polymerase chain reaction result was positive, and who had a Thorax CT scan during hospitalization were included in the study.

RESULTS

Among the patients included in the study, 52.2% were female and the mean age was 61.85 years. The patients applied to the hospital on the average 7th day of their complaints. While 63 patients were unvaccinated (Group 1), 20 were vaccinated with a single dose of CoronaVac (Group 2), 24 with a single dose of BioNTech (Group 3), 38 with 2 doses of CoronaVac (Group 4), 40 with 2 doses of BioNTech (Group 5), and 39 with 3 doses of vaccine (2 doses of CoronaVac followed by a single dose of BioNTech, Group 6). CT-SS ranged from 5 to 23, with a mean of 12.17.CT-SS mean of the groups were determined as 14.17, 13.35, 11.58, 10.87, 11.28, 10.85, respectively. Accordingly, as a result of the comparisons between the groups, the CT-SS levels of the unvaccinated patients found to be significantly higher than the other groups. As the vaccination rates increased, the rate of typical COVID-19 findings on CT was found to be significantly lower.

CONCLUSION

Increased vaccination rates in COVID-19 patients reduce the probability of typical COVID-19 symptoms in the lungs. It also reduces the risk of severe disease and decreases CT Severity Scores. This may lead to a loss of importance of Thorax CT in the diagnosis of COVID-19 pneumonia as the end of the pandemic approaches.

Effectiveness of inactivated COVID-19 vaccines against SARS-CoV-2 Omicron subvariant BF.7 among outpatients in Beijing, China

OBJECTIVE

To evaluate the effectiveness of inactivated vaccines against SARS-CoV-2 Omicron subvariant BF.7.

METHODS

Information was extracted from outpatients diagnosed with COVID-19 between December 19, 2022 and January 5, 2023 at a single center. Univariate and multivariate logistic regression were performed and three adjusted models were conducted. Vaccine effectiveness (VE) was defined as (1 - OR) × 100 %.

RESULTS

Our study comprised a total of 752 outpatients. After adjusting for factors with a P-value < 0.10 in univariable logistic regression, the VE of booster vaccine was 65.4 % (95 % CI6.1-87.3 %, P = 0.037) in comparison with unvaccinated group. Results of the other two adjusted models were similar, which were 66.3 % (95 % CI: 9.0-87.6 %, P = 0.032) and 64.8 % (95 % CI: 3.6-87.1 %, P = 0.042), respectively. Stratified analysis based on underlying diseases indicated that inactivated vaccines did not provide any protection to patients without underlying diseases. In the population with underlying diseases, the VE of booster vaccination was 68.2 % (95 % CI: 8.4-88.9 %, P = 0.034) after adjustment. However, full vaccination did not demonstrate any protection in all models.

CONCLUSION

There was an effectiveness of three-dose inactivated vaccines against Omicron subvariant BF.7. Our findings supported the importance of booster vaccination.

Efficacy and effectiveness of inactivated vaccines against symptomatic COVID-19, severe COVID-19, and COVID-19 clinical outcomes in the general population: a systematic review and meta-analysis

Background

Inactivated, whole-virion vaccines have been used extensively in the SARS-CoV-2 pandemic. Its efficacy and effectiveness across regions have not been systematically evaluated. Efficacy refers to how well a vaccine performs in a controlled environment. Effectiveness refers to how well it performs in real world settings.

Methods

This systematic review and meta-analysis reviewed published, peer-reviewed evidence on all WHO-approved inactivated vaccines and evaluated their efficacy and effectiveness against SARS-CoV-2 infection, symptomatic infection, severe clinical outcomes, and severe COVID-19. We searched Pubmed (including MEDLINE), EMBASE (via OVID), Web of Science Core Collection, Web of Science Chinese Science Citation Database, and Clinicaltrials.gov.

Findings

The final pool included 28 studies representing over 32 million individuals reporting efficacy or effectiveness estimates of complete vaccination using any approved inactivated vaccine between January 1, 2019 and June 27, 2022. Evidence was found for efficacy and effectiveness against symptomatic infection (OR 0.21, 95% CI 0.16-0.27, I2 = 28% and OR 0.32, 95% CI 0.16-0.64, I2 = 98%, respectively) and infection (OR 0.53, 95% CI 0.49-0.57, I2 = 90% and OR 0.31, 95% CI 0.24-0.41, I2 = 0%, respectively) for early SARS-CoV-2 variants of concern (VoCs) (Alpha, Delta), and for waning of vaccine effectiveness with more recent VoCs (Gamma, Omicron). Effectiveness remained robust against COVID-related ICU admission (OR 0.21, 95% CI 0.04-1.08, I2 = 99%) and death (OR 0.08, 95% CI 0.00-2.02, I2 = 96%), although effectiveness estimates against hospitalization (OR 0.44, 95% CI 0.37-0.53, I2 = 0%) were inconsistent.

Interpretation

This study showed evidence of efficacy and effectiveness of inactivated vaccines for all outcomes, although inconsistent reporting of key study parameters, high heterogeneity of observational studies, and the small number of studies of particular designs for most outcomes undermined the reliability of the findings. Findings highlight the need for additional research to address these limitations so that more definitive conclusions can be drawn to inform SARS-CoV-2 vaccine development and vaccination policies.

Funding

Health and Medical Research Fund on COVID-19, Health Bureau of the Government of the Hong Kong SAR.

Inflammatory Response in COVID-19 Depending on the Severity of the Disease and the Vaccination Status

The aim of this study was to analyze the serum concentration of interleukin-6 (IL-6), C-reactive protein (CRP), D-dimer, lactate dehydrogenase (LDH), ferritin, and procalcitonin in COVID-19 patients with different forms of the disease. We performed a prospective cohort study on 137 COVID-19 consecutive patients, divided into four groups according to the severity of the disease as follows: 30 patients in the mild form group, 49 in the moderate form group, 28 in the severe form group, and 30 in the critical form group. The tested parameters were correlated with COVID-19 severity. Significant differences were registered between the form of COVID-19 depending on the vaccination status, between LDH concentrations depending on the virus variant, and in IL-6, CRP, and ferritin concentrations and vaccination status depending on the gender. ROC analysis revealed that D-dimer best predicted COVID-19 severe forms and LDH predicted the virus variant. Our findings confirmed the interdependence relationships observed between inflammation markers in relation to the clinical severity of COVID-19, with all the tested biomarkers increasing in severe and critical COVID-19. IL-6, CRP, ferritin, LDH, and D-dimer were increased in all COVID-19 forms. These inflammatory markers were lower in Omicron-infected patients. The unvaccinated patients developed more severe forms compared to the vaccinated ones, and a higher proportion of them needed hospitalization. D-dimer could predict a severe form of COVID-19, while LDH could predict the virus variant.

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.

Impact of inactivated COVID-19 vaccines on lung injury in B.1.617.2 (Delta) variant-infected patients

BACKGROUND

Chest computerized tomography (CT) scan is an important strategy that quantifies the severity of COVID-19 pneumonia. To what extent inactivated COVID-19 vaccines could impact the COVID-19 pneumonia on chest CT is not clear.

METHODS

This study recruited 357 SARS-COV-2 B.1.617.2 (Delta) variant-infected patients admitted to the Second Hospital of Nanjing from July to August 2021. An artificial intelligence-assisted CT imaging system was used to quantify the severity of COVID-19 pneumonia. We compared the volume of infection (VOI), percentage of infection (POI) and chest CT scores among patients with different vaccination statuses.

RESULTS

Of the 357 Delta variant-infected patients included for analysis, 105 were unvaccinated, 72 were partially vaccinated and 180 were fully vaccinated. Fully vaccination had the least lung injuries when quantified by VOI (median VOI of 222.4 cm³, 126.6 cm³ and 39.9 cm³ in unvaccinated, partially vaccinated and fully vaccinated, respectively; p < 0.001), POI (median POI of 7.60%, 3.55% and 1.20% in unvaccinated, partially vaccinated and fully vaccinated, respectively; p < 0.001) and chest CT scores (median CT score of 8.00, 6.00 and 4.00 in unvaccinated, partially vaccinated and fully vaccinated, respectively; p < 0.001). After adjustment for age, sex, comorbidity, time from illness onset to hospitalization and viral load, fully vaccination but not partial vaccination was significantly associated with less lung injuries quantified by VOI {adjust coefficient[95%CI] for "full vaccination": - 106.10(- 167.30,44.89); p < 0.001}, POI {adjust coefficient[95%CI] for "full vaccination": - 3.88(- 5.96, - 1.79); p = 0.001} and chest CT scores {adjust coefficient[95%CI] for "full vaccination": - 1.81(- 2.72, - 0.91); p < 0.001}. The extent of reduction of pulmonary injuries was more profound in fully vaccinated patients with older age, having underlying diseases, and being female sex, as demonstrated by relatively larger absolute values of adjusted coefficients. Finally, even within the non-severe COVID-19 population, fully vaccinated patients were found to have less lung injuries.

CONCLUSION

Fully vaccination but not partially vaccination could significantly protect lung injury manifested on chest CT. Our study provides additional evidence to encourage a full course of vaccination.

Assessing the transition of COVID-19 burden towards the young population while vaccines are rolled out in China

SARS-CoV-2 infection causes most cases of severe illness and fatality in older age groups. Over 92% of the Chinese population aged ≥12 years has been fully vaccinated against COVID-19 (albeit with vaccines developed against historical lineages). At the end of October 2021, the vaccination programme has been extended to children aged 3-11 years. Here, we aim to assess whether, in this vaccination landscape, the importation of Delta variant infections could shift COVID-19 burden from adults to children. We developed an age-structured susceptible-infectious-removed model of SARS-CoV-2 transmission to simulate epidemics triggered by the importation of Delta variant infections and project the age-specific incidence of SARS-CoV-2 infections, cases, hospitalizations, intensive care unit admissions, and deaths. In the context of the vaccination programme targeting individuals aged ≥12 years, and in the absence of non-pharmaceutical interventions, the importation of Delta variant infections could have led to widespread transmission and substantial disease burden in mainland China, even with vaccination coverage as high as 89% across the eligible age groups. Extending the vaccination roll-out to include children aged 3-11 years (as it was the case since the end of October 2021) is estimated to dramatically decrease the burden of symptomatic infections and hospitalizations within this age group (39% and 68%, respectively, when considering a vaccination coverage of 87%), but would have a low impact on protecting infants. Our findings highlight the importance of including children among the target population and the need to strengthen vaccination efforts by increasing vaccine effectiveness.

Relative vaccine effectiveness against Delta and Omicron COVID-19 after homologous inactivated vaccine boosting: a retrospective cohort study

ObjectiveTwo COVID-19 outbreaks occurred in Henan province in early 2022-one was a Delta variant outbreak and the other was an Omicron variant outbreak. COVID-19 vaccines used at the time of the outbreak were inactivated, 91.8%; protein subunit, 7.5%; and adenovirus5-vectored, 0.7% vaccines. The outbreaks provided an opportunity to evaluate variant-specific breakthrough infection rates and relative protective effectiveness of homologous inactivated COVID-19 vaccine booster doses against symptomatic infection and pneumonia.

DESIGN

Retrospective cohort study METHODS: We evaluated relative vaccine effectiveness (rVE) with a retrospective cohort study of close contacts of infected individuals using a time-dependent Cox regression model. Demographic and epidemiologic data were obtained from the local Centers for Disease Control and Prevention; clinical and laboratory data were obtained from COVID-19-designated hospitals. Vaccination histories were obtained from the national COVID-19 vaccination dataset. All data were linked by national identification number.

RESULTS

Among 784 SARS-CoV-2 infections, 379 (48.3%) were caused by Delta and 405 (51.7%) were caused by Omicron, with breakthrough rates of 9.9% and 17.8%, respectively. Breakthrough rates among boosted individuals were 8.1% and 4.9%. Compared with subjects who received primary vaccination series ≥180 days before infection, Cox regression modelling showed that homologous inactivated booster vaccination was statistically significantly associated with protection from symptomatic infection caused by Omicron (rVE 59%; 95% CI 13% to 80%) and pneumonia caused by Delta (rVE 62%; 95% CI 34% to 77%) and Omicron (rVE 87%; 95% CI 3% to 98%).

CONCLUSIONS

COVID-19 vaccination in China provided good protection against symptomatic COVID-19 and COVID-19 pneumonia caused by Delta and Omicron variants. Protection declined 6 months after primary series vaccination but was restored by homologous inactivated booster doses given 6 months after the primary series.

Artificial Cell Membrane Polymersome-Based Intranasal Beta Spike Formulation as a Second Generation Covid-19 Vaccine

Current parenteral coronavirus disease 2019 (Covid-19) vaccines inadequately protect against infection of the upper respiratory tract. Additionally, antibodies generated by wild type (WT) spike-based vaccines poorly neutralize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. To address the need for a second-generation vaccine, we have initiated a preclinical program to produce and evaluate a potential candidate. Our vaccine consists of recombinant Beta spike protein coadministered with synthetic CpG adjuvant. Both components are encapsulated within artificial cell membrane (ACM) polymersomes, synthetic nanovesicles efficiently internalized by antigen presenting cells, including dendritic cells, enabling targeted delivery of cargo for enhanced immune responses. ACM vaccine is immunogenic in C57BL/6 mice and Golden Syrian hamsters, evoking high serum IgG and neutralizing responses. Compared to an ACM-WT spike vaccine that generates predominantly WT-neutralizing antibodies, the ACM-Beta spike vaccine induces antibodies that neutralize WT and Beta viruses equally. Intramuscular (IM)-immunized hamsters are strongly protected from weight loss and other clinical symptoms after the Beta challenge but show delayed viral clearance in the upper airway. With intranasal (IN) immunization, however, neutralizing antibodies are generated in the upper airway concomitant with rapid and potent reduction of viral load. Moreover, antibodies are cross-neutralizing and show good activity against Omicron. Safety is evaluated in New Zealand white rabbits in a repeated dose toxicological study under Good Laboratory Practice (GLP) conditions. Three doses, IM or IN, at two-week intervals do not induce an adverse effect or systemic toxicity. Cumulatively, these results support the application for a Phase 1 clinical trial of ACM-polymersome-based Covid-19 vaccine (ClinicalTrials.gov identifier: NCT05385991).

Mental health and chest CT scores mediate the relationship between COVID-19 vaccination status and seroconversion time: A cross-sectional observational study in B.1.617.2 (Delta) infection patients

Background

The coronavirus disease (COVID-19) pandemic, which has been ongoing for more than 2 years, has become one of the largest public health issues. Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is one of the most important interventions to mitigate the COVID-19 pandemic. Our objective is to investigate the relationship between vaccination status and time to seroconversion.

Methods

We conducted a cross-sectional observational study during the SARS-CoV-2 B.1.617.2 outbreak in Jiangsu, China. Participants who infected with the B.1.617.2 variant were enrolled. Cognitive performance, quality of life, emotional state, chest computed tomography (CT) score and seroconversion time were evaluated for each participant. Statistical analyses were performed using one-way ANOVA, univariate and multivariate regression analyses, Pearson correlation, and mediation analysis.

Results

A total of 91 patients were included in the analysis, of whom 37.3, 25.3, and 37.3% were unvaccinated, partially vaccinated, and fully vaccinated, respectively. Quality of life was impaired in 30.7% of patients, especially for mental component summary (MCS) score. Vaccination status, subjective cognitive decline, and depression were risk factors for quality-of-life impairment. The chest CT score mediated the relationship of vaccination status with the MCS score, and the MCS score mediated the relationship of the chest CT score with time to seroconversion.

Conclusion

Full immunization course with an inactivated vaccine effectively lowered the chest CT score and improved quality of life in hospitalized patients. Vaccination status could influence time to seroconversion by affecting CT score and MCS score indirectly. Our study emphasizes the importance of continuous efforts in encouraging a full vaccination course.

A comparative characterization of SARS-CoV-2-specific T cells induced by mRNA or inactive virus COVID-19 vaccines

Unlike mRNA vaccines based only on the spike protein, inactivated severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) vaccines should induce a diversified T cell response recognizing distinct structural proteins. Here, we perform a comparative analysis of SARS-CoV-2-specific T cells in healthy individuals following vaccination with inactivated SARS-CoV-2 or mRNA vaccines. Relative to spike mRNA vaccination, inactivated vaccines elicit a lower magnitude of spike-specific T cells, but the combination of membrane, nucleoprotein, and spike-specific T cell response is quantitatively comparable with the sole spike T cell response induced by mRNA vaccine, and they efficiently tolerate the mutations characterizing the Omicron lineage. However, this multi-protein-specific T cell response is not mediated by a coordinated CD4 and CD8 T cell expansion but by selective priming of CD4 T cells. These findings can help in understanding the role of CD4 and CD8 T cells in the efficacy of the different vaccines to control severe COVID-19 after Omicron infection.

A Case-Case Study on the Effect of Primary and Booster immunization with China-produced COVID-19 Vaccines on Prevention of Pneumonia and Viral Load among Vaccinated Persons infected by Delta and Omicron Variants

Using a three-prefecture, two-variant COVID-19 outbreak in Henan province in January 2022, we evaluated the associations of primary and booster immunization with China-produced COVID-19 vaccines and COVID-19 pneumonia and SARS-CoV-2 viral load among persons infected by Delta or Omicron variant. We obtained demographic, clinical, vaccination, and multiple Ct values of infections ≥3 years of age. Vaccination status was either primary series ≥180 days prior to infection; primary series <180 days prior to infection, or booster dose recipient. We used logistic regression to determine odds ratios (OR) of Delta and Omicron COVID-19 pneumonia by vaccination status. We analyzed minimum Ct values by vaccination status, age, and variant. Of 826 eligible cases, 405 were Delta and 421 were Omicron cases; 48.9% of Delta and 19.0% of Omicron cases had COVID-19 pneumonia. Compared with full primary vaccination ≥180 days before infection, the aOR of pneumonia was 0.48 among those completing primary vaccination <180 days and 0.18 among booster recipients among these Delta infections. Among Omicron infections, the corresponding aOR was 0.34 among those completing primary vaccination <180 days. There were too few (ten) Omicron cases among booster dose recipients to calculate a reliable OR. There were no differences in minimum Ct values by vaccination status among the 356 Delta cases or 70 Omicron cases. COVID-19 pneumonia was less common among Omicron cases than Delta cases. Full primary vaccination reduced pneumonia effectively for 6 months; boosting six months after primary vaccination resulted in further reduction. We recommend accelerating the pace of booster dose administration.

COVID-19 infection among vaccinated and unvaccinated: Does it make any difference?

OBJECTIVE

There is a probability that vaccination may lead to reduction in the severity and complications associated with COVID-19 infection among hospitalized patients. This study aimed to determine the characteristics, clinical profiles, and outcomes of COVID-19 infection in vaccinated and non-vaccinated patients.

DESIGN AND DATA SOURCES

This prospective observational cohort study was conducted at the Aga Khan University Hospital (AKUH) and recruited COVID-19 patients admitted between June 1st and September 30th, 2021. Patients' demographics, date of admission and discharge, comorbid conditions, immunization status for COVID-19 infection, presenting complaints, lab workup and computed tomography (CT) scan findings were obtained from the medical records. The primary outcome of the study was patients' condition at discharge and the secondary outcomes included level of care, length of stay (LOS), requirement of non-invasive ventilation (NIV) and inotropic support.

RESULTS

Among a cohort of 434 patients, 37.7% (n = 164), 6.6% (n = 29) and 55.5% (n = 241) were fully vaccinated, partially vaccinated, and unvaccinated, respectively. Around 3% and 42.9% of the patient required inotropic and NIV support respectively; however, there was no discernible difference between them in terms of vaccination status. In case of unvaccinated patients there were significantly increased number of critical care admissions (p-value 0.043). Unvaccinated patients had significantly higher median serum procalcitonin, ferritin, LDH and D-dimer levels. Around 5.3% (n = 23) of the patient required invasive ventilation and it was more common in unvaccinated patients (p-value 0.04). Overall, mortality rate was 12.2% (n = 53) and this was higher (16.2%, n = 39) in unvaccinated patients as compared to fully vaccinated patients (6.1%, n = 10, p-value 0.006).

CONCLUSIONS

Through this preliminary data, we can conclude that patient can develop severe and critical COVID-19 infection despite being vaccinated but this proportion is low as compared to unvaccinated population. So, uninterrupted endeavors need to be done to vaccinate as many individuals as possible. Furthermore, more effective vaccinations need to be developed to lessen the high death toll of COVID-19 infection.

Effects of short-term ambient particulate matter exposure on the risk of severe COVID-19

OBJECTIVES

Previous studies have suggested a relationship between outdoor air pollution and the risk of coronavirus disease 2019 (COVID-19). However, there is a lack of data related to the severity of disease, especially in China. This study aimed to explore the association between short-term exposure to outdoor particulate matter (PM) and the risk of severe COVID-19.

METHODS

We recruited patients diagnosed with COVID-19 during a recent large-scale outbreak in eastern China caused by the Delta variant. We collected data on meteorological factors and ambient air pollution during the same time period and in the same region where the cases occurred and applied a generalized additive model (GAM) to analyze the effects of short-term ambient PM exposure on the risk of severe COVID-19.

RESULTS

A total of 476 adult patients with confirmed COVID-19 were recruited, of which 42 (8.82%) had severe disease. With a unit increase in PM₁₀, the risk of severe COVID-19 increased by 81.70% (95% confidence interval [CI]: 35.45, 143.76) at a lag of 0-7 days, 86.04% (95% CI: 38.71, 149.53) at a lag of 0-14 days, 76.26% (95% CI: 33.68, 132.42) at a lag of 0-21 days, and 72.15% (95% CI: 21.02, 144.88) at a lag of 0-28 days. The associations remained significant at lags of 0-7 days, 0-14 days, and 0-28 days in the multipollutant models. With a unit increase in PM_2.5, the risk of severe COVID-19 increased by 299.08% (95% CI: 92.94, 725.46) at a lag of 0-7 days, 289.23% (95% CI: 85.62, 716.20) at a lag of 0-14 days, 234.34% (95% CI: 63.81, 582.40) at a lag of 0-21 days, and 204.04% (95% CI: 39.28, 563.71) at a lag of 0-28 days. The associations were still significant at lags of 0-7 days, 0-14 days, and 0-28 days in the multipollutant models.

CONCLUSIONS

Our results indicated that short-term exposure to outdoor PM was positively related to the risk of severe COVID-19, and that reducing air pollution may contribute to the control of COVID-19.

COVID-19 pandemic: the delta variant, T-cell responses, and the efficacy of developing vaccines

Background

The mayhem COVID-19 that was ushered by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) was declared pandemic by the World Health Organization in March 2020. Since its initial outbreak in late 2019, the virus has affected hundreds of million adults in the world and killing millions in the process. After the approval of newly developed vaccines, severe challenges remain to manufacture and administer them to the adult population globally in quick time. However, we have witnessed several mutations of the virus leading to ‘waves’ of viral spread and mortality. WHO has categorized these mutations as variants of concern (VOCs) and variants of interest (VOIs). The mortality due to COVID-19 has also been associated with various comorbidities and improper immune response. This has created further complications in understanding the nature of the SARS-CoV2–host interaction that has fuelled doubts in the efficacy of the approved vaccines. Whether there is requirement of booster dose and whether the impending wave could affect the children are some of the hotly debated topics.

Materials and Methods

A systematic literature review of PubMed, Medline, Scopus, Google Scholar was utilized to understand the nature of Delta variant and how it alters our T-cell responses and cytokine production and neutralizes vaccine-generated antibodies.

Conclusion

In this review, we discuss the variants of SARS-CoV2 with specific focus on the Delta variant. We also specifically review the T-cell response against the virus and bring a narrative of various factors that may hold the key to fight against this marauding virus.

Effectiveness of COVID-19 Vaccines against Delta Variant (B.1.617.2): A Meta-Analysis

Objectives: The highly transmissible COVID-19 Delta variant (DV) has contributed to a surge in cases and exacerbated the worldwide public health crisis. Several COVID-19 vaccines play a significant role in a high degree of protection against the DV. The primary purpose of this meta-analysis is to estimate the pooled effectiveness of the COVID-19 vaccines against the DV in terms of risk ratio (RR) among fully vaccinated, compared to unvaccinated populations. Methods: We carried out a systematic review, with meta-analysis of original studies focused on COVID-19 vaccines effectiveness against a DV clinical perspective among fully COVID-19 vaccinated populations, compared to placebo (unvaccinated populations), published between 1 May 2021 and 30 September 2021. Eleven studies containing the data of 17.2 million participants were identified and included in our study. Pooled estimates of COVID-19 vaccines effectiveness (i.e., risk ratio, RR) against the DV with 95% confidence intervals were assessed using random-effect models. Publication bias was assessed using Egger's regression test and funnel plot to investigate potential sources of heterogeneity and identify any differences in study design. Results: A total population of 17.2 million (17,200,341 people) were screened for the COVID-19 vaccines' effectiveness against the DV. We found that 61.13% of the study population were fully vaccinated with two doses of COVID-19 vaccines. The weighted pooled incidence of COVID-19 infection was more than double (20.07%) among the unvaccinated population, compared to the fully vaccinated population (8.16%). Overall, the effectiveness of the COVID-19 vaccine against the DV was 85% (RR = 0.15, 95% CI: 0.07-0.31). The effectiveness of COVID-19 vaccines varied slidably by study designs, 87% (RR = 0.13, 95% CI: 0.06-0.30) and 84% (RR = 0.16, 95% CI: 0.02, 1.64) for cohort and case-control studies, respectively. Conclusions: The effectiveness of COVID-19 vaccines were noted to offer higher protection against the DV among populations who received two vaccine doses compared with the unvaccinated population. This finding would help efforts to maximise vaccine coverage (i.e., at least 60% to 70% of the population), with two doses among vulnerable populations, in order to have herd immunity to break the chain of transmission and gain greater overall population protection more rapidly.