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1.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-314433

ABSTRACT

Background: COVID-19 is a rapidly spreading disease that is causing extensive burdens across the world. Effective vaccines to prevent COVID-19 are urgently needed. Several vaccines have been accepted by regulatory authorities, but their individual and relative efficacy and adverse effects remain unclear.Methods: We conducted a systematic review of randomised clinical trials with network meta-analysis and Trial Sequential Analysis (TSA). Searches were made in CENTRAL, MEDLINE, Embase, and other sources from inception to May 12, 2021 for randomised clinical trials, assessing vaccines for COVID-19 . At least two independent reviewers screened studies, extracted data, and assessed the risk of bias. Our primary outcomes included all-cause mortality, vaccine efficacy, and serious adverse events.Findings We identified 22 trials;19 trials randomising 144 434 participants were included in our analyses. mRNA vaccines (efficacy 95%, 95% confidence interval (CI) 92% to 97%;69 285 participants;2 trials;GRADE: moderate certainty) and viral vector vaccines (efficacy 68%, 95% CI 61% to 74%;71 401 participants;5 trials;GRADE: low certainty) prevented COVID-19. Viral vector vaccines decreased mortality (risk ratio (RR) 0·25, 95% CI 0·09 to 0·67;67 563 participants;3 trials, GRADE: low certainty), but data on mRNA vaccines are still imprecise. None of the vaccines showed evidence of a difference on serious adverse events, but observational evidence indicated rare serious adverse events. mRNA and viral vector vaccines increased the risk of non-serious adverse events. Interpretation The evidence suggests that mRNA vaccines and viral vector vaccines are effective in preventing COVID-19. mRNA vaccines seem most effective in preventing COVID-19, but viral vector vaccines seem most effective in reducing mortality. mRNA vaccines and viral vector vaccines increase the risks of rare serious adverse events according to observational evidence. Further trials and longer follow-up are necessary to provide better insight into the safety profile of these vaccines. Registration Information: PROSPERO CRD42020196492. Funding Information: The Copenhagen Trial Unit funded the wages for the authors affiliated with the Copenhagen Trial Unit. None of the authors received any specific funding related to the review. Declaration of Interests: The authors declare that they have no known competing interests.

2.
PLoS One ; 17(1): e0260733, 2022.
Article in English | MEDLINE | ID: covidwho-1643240

ABSTRACT

BACKGROUND: COVID-19 is rapidly spreading causing extensive burdens across the world. Effective vaccines to prevent COVID-19 are urgently needed. METHODS AND FINDINGS: Our objective was to assess the effectiveness and safety of COVID-19 vaccines through analyses of all currently available randomized clinical trials. We searched the databases CENTRAL, MEDLINE, Embase, and other sources from inception to June 17, 2021 for randomized clinical trials assessing vaccines for COVID-19. At least two independent reviewers screened studies, extracted data, and assessed risks of bias. We conducted meta-analyses, network meta-analyses, and Trial Sequential Analyses (TSA). Our primary outcomes included all-cause mortality, vaccine efficacy, and serious adverse events. We assessed the certainty of evidence with GRADE. We identified 46 trials; 35 trials randomizing 219 864 participants could be included in our analyses. Our meta-analyses showed that mRNA vaccines (efficacy, 95% [95% confidence interval (CI), 92% to 97%]; 71 514 participants; 3 trials; moderate certainty); inactivated vaccines (efficacy, 61% [95% CI, 52% to 68%]; 48 029 participants; 3 trials; moderate certainty); protein subunit vaccines (efficacy, 77% [95% CI, -5% to 95%]; 17 737 participants; 2 trials; low certainty); and viral vector vaccines (efficacy 68% [95% CI, 61% to 74%]; 71 401 participants; 5 trials; low certainty) prevented COVID-19. Viral vector vaccines decreased mortality (risk ratio, 0.25 [95% CI 0.09 to 0.67]; 67 563 participants; 3 trials, low certainty), but comparable data on inactivated, mRNA, and protein subunit vaccines were imprecise. None of the vaccines showed evidence of a difference on serious adverse events, but observational evidence suggested rare serious adverse events. All the vaccines increased the risk of non-serious adverse events. CONCLUSIONS: The evidence suggests that all the included vaccines are effective in preventing COVID-19. The mRNA vaccines seem most effective in preventing COVID-19, but viral vector vaccines seem most effective in reducing mortality. Further trials and longer follow-up are necessary to provide better insight into the safety profile of these vaccines.


Subject(s)
COVID-19 Vaccines/administration & dosage , COVID-19/epidemiology , COVID-19/prevention & control , SARS-CoV-2/pathogenicity , /administration & dosage , COVID-19/mortality , COVID-19/pathology , COVID-19 Vaccines/adverse effects , Humans , Network Meta-Analysis , Randomized Controlled Trials as Topic , SARS-CoV-2/immunology , Survival Analysis , Treatment Outcome , Vaccines, Inactivated , Vaccines, Subunit , /adverse effects
3.
Int J Infect Dis ; 102: 577-583, 2021 Jan.
Article in English | MEDLINE | ID: covidwho-1006446

ABSTRACT

OBJECTIVE: Significant morbidity and mortality have occurred in the USA, Europe, and Asia due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), whereas the numbers of infections and deaths in sub-Saharan Africa (SSA) have remained comparatively low. It has been hypothesized that exposure of the population in SSA to other coronaviruses prior to the COVID-19 pandemic resulted in some degree of cross-protection against SARS-CoV-2 infection and pathogenesis. We evaluated this hypothesis by comparing SARS-CoV-2 cross-reactive antibodies in pre-pandemic plasma samples collected from SSA and the USA. METHOD: Pre-COVID-19 pandemic plasma samples from SSA and the USA were collected and tested by immunofluorescence assay against the spike and nucleocapsid proteins of all known human coronaviruses (HCoVs). RESULTS: The prevalence of SARS-CoV-2 serological cross-reactivity was significantly higher in samples from SSA compared with the USA. Most of these cross-reactive samples cross-recognized the SARS-CoV-2 nucleocapsid protein and the spike proteins of other HCoVs. Nucleocapsid proteins from HCoV-NL63 and HCoV-229E were detected in most samples, thereby implicating prior exposure to these two HCoVs as the likely source of cross-reactive antibodies against SARS-CoV-2. CONCLUSION: The low incidences of SARS-CoV-2 infection and disease in SSA appear to be correlated with the pre-pandemic serological cross-recognition of HCoVs, which are substantially more prevalent in SSA than the USA.


Subject(s)
Antibodies, Viral/blood , COVID-19/blood , SARS-CoV-2/immunology , Adult , Africa South of the Sahara/epidemiology , COVID-19/epidemiology , COVID-19/virology , Cross Reactions , Female , Humans , Male , Middle Aged , Nucleocapsid Proteins/immunology , Pandemics , Young Adult
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