Impact of COVID-19 Vaccinations in India: A State-wise Analysis (Preprint)

Abstract

Ever since the emergence of COVID-19 and its consequent spread across continents, engulfing both advanced and developing nations, COVID-19 vaccine was considered to be main weapon to curb the spread of virus. The COVID-19 vaccination program in India started after the first wave of infections (March – December 2020) had almost subsided.

In this work, the objective is to perform a state-wise analysis to assess the impact of vaccination in slowing down the spread of infections during the second COVID-19 wave (February – October 2021) in India. The prediction accuracy of the proposed model with the optimal lag length (in days) after including the impact of vaccination is evaluated and compared with a model without it. A total of 21 states are chosen for the analysis encompassing 97% of the Indian population.

We use the generalized Gompertz curve to study the COVID-19 outbreak. The generalized Gompertz model is then modified to study the impact of vaccination to slow down the spread of COVID-19. The modified model considers the cumulative proportion of individuals having the first COVID-19 vaccine shot in each state as the explanatory variable.

We observe that, out of 21 states, 16 states show the impact of vaccines in curbing the spread of COVID-19. However, in states like Telangana, West Bengal, Tamil Nadu, Rajasthan, and Kerala, we do not conclusively observe the impact of vaccination during the study period.

The effectiveness of the COVID-19 vaccine depends on many factors. Some of them are not directly measurable. Using only COVID-19 infection cases and the vaccination data in the proposed model, we conclude that overall the vaccination program effectively curbed the spread of COVID-19 in India.