Efficacy and Effectiveness of SARS-CoV-2 vaccine: A systematic review and a meta-analysis.

Abstract Background SARS coronavirus number 2 or SARS-CoV-2 emerged as a pandemic in 2019 and affected millions of people with a large number of deaths. Since no cure for this highly spreadable virus is known till now the need for a rapid vaccine development started early and the vaccination process started in December 2020 with many types of vaccines of different techniques.This research aimed to shed the light on different studies evaluating the efficacy, effectiveness of COVID-19 vaccines in phase III trials.Method Online database search was performed, and all relevant randomized controlled trials and observational studies considering COVID-19 vaccination by any type of vaccine and to any age were included. A meta-analysis was conducted to measure the efficacy/ effectiveness of COVID-19 vaccines to prevent mortality and to reduce severe infection after the first & the second dose. Assessment of risk of bias, publication bias & heterogenicity were also performed.Results From 21567 screened articles twenty-five studies were eligible for quantitative analysis. The odds ratio of mortality 7 days after full vaccination decreased significantly among vaccinated compared to the unvaccinated group OR=0.14 (95CI, 0.05-0.41), I2=63%. In total 213 of 4807683 vaccinated people developed severe COVID-19 one week after the second dose, compared to 3298 of unvaccinated 1915476 subjects. The OR of having severe COVID-19 decreased by 0.08 (0.03-0.25), I2 was 74%. Vaccination was also significant in reducing COVID-19 infection in either symptomatic or asymptomatic cases.Conclusion This study showed that most vaccines have comparable efficacy and effectiveness, and it is believed that with the mass vaccination of COVID-19, it is possible to control the infection and end this global pandemic