Heterologous Protection to COVID-19 with BCG Vaccine: Deciphering the Reality Using Meta-Analysis Approach

Anurag Singh,Lakshya Gupta,Vandana Gupta

doi:10.29245/2578-3009/2020/4.1199

Abstract

The coronavirus disease (COVID-19) emerged in China in December 2019 and has since spread to over 188 countries affecting millions of individuals. Several reports in favour or against the heterologous protection conferred by the BCG vaccine against COVID-19 came up in the initial days of the pandemic and continue to do so. In this study, we compared the three worst-affected nations: The USA, India, and Brazil, their current pandemic scenario, and their respective national BCG immunization policies. USA recommends BCG vaccine only to a specific group of people and never had a national immunization scheme in place. Meanwhile, India introduced a nationwide scheme as early as 1948 and continues to endorse BCG immunization at birth. Brazil used the oral route to administer the BCG vaccine till 1976, and then shifted to intradermal injection. The correlation coefficient for the total number of cases, cases per million, the total number of deaths, deaths per million and case fatality rate ranges between 0.81-0.98. This indicates a very strong positive correlation in the various epidemiological parameters between countries with no national immunization scheme (USA) and countries with stringent national policies on BCG vaccination. The strongest correlation exists between the USA and Brazil followed by Brazil and India which is very closely followed by the USA and India. We found no consistent evidence to infer in favour of the hypothesis that BCG provides any non-specific protection against COVID-19.

Highlights

It all started back in December 2019 when the case(s) of pneumonia of unknown etiology came up in Wuhan, China, and spread across the world in over 188 countries within months.Investigations and whole-genome sequencing indicated the origin of a new coronavirus that has skipped from its natural reservoir “bat”[1]; to humans via a highly probable intermediate host “pangolin”[2] that is sold illegally in Chinese markets
We found no consistent evidence to infer in favour of the hypothesis that Bacillus Calmette-Guérin COVID-19 (BCG) provides any non-specific protection against COVID-19
The SARS-CoV-2 infection and mortality data of the three worst-affected nations provides a unique combination for comparatively analysing whether BCG is exerting heterologous protection against SARS-CoV-2 infection

Summary

Introduction

It all started back in December 2019 when the case(s) of pneumonia of unknown etiology came up in Wuhan, China, and spread across the world in over 188 countries within months. Investigations and whole-genome sequencing indicated the origin of a new coronavirus that has skipped from its natural reservoir “bat”[1]; to humans via a highly probable intermediate host “pangolin”[2] that is sold illegally in Chinese markets. This suggested a zoonotic origin like many other newly emerged viruses including Nipah, SARS-CoV, MERS-CoV, Ebola, Marburg, etc. Cases of shedding of viral RNA in feces[6] have been documented

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Results

Conclusion