Epidemic Trajectory in the Absence of Non-Pharmacological Interventions in India: An Insight into Post Vaccine Introduction Phase

Background: Non-Pharmacological Interventions (NPIs) have proven to be effective in controlling and reducing the spread of SARS-CoV-2 in the population. During the year 2020, before vaccine introduction, India has been through various phases of COVID-19 pandemic response such as nationwide lockdown phase 1 to 4 and unlock phases 1-8. Although India’s vaccination program against COVID-19 has started, it is still in the initial phases and considering the humongous population of India, coverage of entire population with vaccine needs time. Methodology: We designed a model showing the projections of expected incident cases of COVID-19 under two scenarios for the month of February 2021. In the first scenario, Rt value expected to be observed during February 2021 if all the NPIs are removed was considered. In the second scenario, Rt value projected as per the current trend with NPIs in place was considered. Model projections of both these scenarios were done for India and also for Delhi. Result: Our simulation model quantifies the effect of Non-pharmacological interventions on the current pandemic situation in India and Delhi, which concludes that relaxation in preventive measures or COVID-19 appropriate behaviors or ceasing of NPIs shall see an exponential rise in the daily incident cases. Comparing the trajectories for India and Delhi, it can be deduced that if NPIs cease to exist for one month, the daily incident cases can be many times higher of normal in India and also in Delhi by the end of February 2021. Conclusion: NPIs remain to play a major role in containing the spread and minimizing the effects of COVID-19 pandemic. Any kind of relaxation in NPIs can lead to sudden surge of incident cases and correspondingly may increase the death toll.