RESUMO
This article provides a systematic assessment of the efficacy, risks, and methodological quality of evidence from five major publicly available vaccine trials. Results from Pfizer-BioNTech mRNA, Moderna-US NIH mRN-1273, AstraZeneca-Oxford ChAdOx1 nCov-19, Gamaleya GamCovidVac (Sputnik V), and Ad26.COV2.S Johnson & Johnson vaccines were included. Extracted benefits and risks data from each trial were summarized using the GRADE approach denoting the overall certainty of evidence along with relative and absolute effects. Relative risk reduction across all five vaccine trials ranged from 45% to 96%. Absolute risk reduction in symptomatic COVID-19 ranged from 6 to 17 per 1000 across trials. None of the vaccines were associated with a significant increase in serious adverse events compared to placebo. The overall certainty of evidence varied from low to moderate. All five vaccines are effective and safe, but suggest room for improvement in the conduct of large-scale vaccine trials. Certainty of evidence was downrated due to risk of bias, which can be mitigated by improving transparency and thoroughness in conduct and reporting of outcomes.
