Abstract
COVID-19 has caused significant morbidity and mortality around the world. However, it has been noticed that case-fatality rates have been significantly higher in Europe and North America compared to the Asia, Middle East and Africa. This could be due to several factors which include average age of the population, testing and tracing facilities, social distancing measures and difference in immunogenic response to SARS-COV-2. In this report, we have discussed the factors which may affect a population to develop herd immunity against COVID-19. We have hypothesized here that frequent prior exposure to other coronaviruses in Asian population might impart partial immunity to COVID-19. This may be the reason for significant lower number of case fatalities seen in this region compared to the west. We, therefore, propose molecular immunological studies to correlate prior exposure to coronaviruses with disease severity. This will help us to develop therapeutic targets to treat severe infection with COVID-19.