Of Cross-Immunity, Herd Immunity and Country-Specific Plans: Experiences from COVID-19 in India

India has witnessed a high number of COVID-19 cases, but mortality has been quite low, and most cases have been asymptomatic or mild. In early April, we had hypothesized a low COVID-19 mortality in India, based on the concept of cross-immunity. Several recent studies have demonstrated cross-reactive T-cells against SARS-CoV-2 in those exposed to infections by endemic ‘common cold’ coronaviruses. Hence, evidence supporting our hypothesis has started showing up. Higher cross-immunity to a severe form of COVID-19 may result in a faster attainment of herd immunity in India, of which there is evidence from the case of the national capital New Delhi, where despite significant easing of restrictive lockdown measures, active cases have gone down since end of June. While COVID-19 mortality in India has been low, restrictive measures such as lockdown and overly expensive measures such as enhanced testing has resulted in a burden on the health economics as well as the society. In the backdrop of high immunity to severe manifestations of COVID-19 in India, we propose a restructuring of the health services and approach to COVID-19. In the process, we emphasize why the development of country-specific plans for tackling epidemics becomes important.