BCG vaccination provides protection against COVID 19: A Systematic review and meta-analysis

Abstract Context: Lower morbidity and mortality in few geographic locations on the globe suffering with SARS-CoV-2 has been associated with the existing or previously followed long standing BCG vaccination policy amongst infants. But does that hold true that today after years of BCG vaccination few adults have better prognosis or is it just confounding due to differential disease burden, population density, testing facilities or improper reporting. The purpose was to evaluate and correlate this effect systematically.Evidence acquisition: Detailed electronic search for randomised controlled trials and observational studies in PubMed, Cochrane database and clinicaltrials.gov for eligible studies was performed. We performed a meta-analysis to provide pooled esimate of correlation of mortality with BCG vaccination policy from 4 studies.Results: 114 number of studies were yielded on search strategy and 28 observational studies were finally included for analysis. From our results we can say that BCG vaccination causes a decrease in COVID-19 incidence and mortality. But these results must be interpreted cautiously as lot of confounding factors were present in included studies, which can affect the outcome.Conclusion: The evidence of BCG vaccination for protection against COVID-19 can’t be ruled out as evidence from many studies support the hypothesis but the evidence of well conducted RCTs and observational studies can strengthen the evidence.