The Peak of COVID-19 in India

TLDR: The exponential model unravels the uncertainty about the peak and curvature of COVID-19 disease, and shows that the SARIMA model is suitable for projecting daily confirmed cases.

Abstract: Introduction: Following the USA, India ranks the second position in the world for COVID 19 cases with the highest number of daily confirmed cases since September 2020. The peak of COVID-19 cases is the most warranted feature for understanding the curvature of COVID 19 cases. Aim: This study aims to analyse the growth rates of the daily confirmed cases and to provide an expected count of the peak of daily confirmed cases. Data: We retrieved data from an Application Programming Interface portal https://www.covid19india.org/ which is open access and publicly available. Methods: Exponential model was applied to estimate the growth rates of daily confirmed cases. The estimated growth rates were used for calculating the doubling time. The Lotka Euler method was applied to calculate the effective reproduction rate. SARIMA model was developed for the growth rates to predict daily confirmed cases. Results: Results show the best fit of the exponential model over the daily confirmed cases. The growth rates estimated from the exponential model shows an unsteady, modest decline. Doubling time shows a linear increase. The effective reproduction rate declined from 3.6 persons in the third week of March 2020 to 1.14 persons at the end of August 2020. The diagnosis of the developed SARIMA model confirmed no trends in the residuals, no outliers, and nearly constant variance. The forecast suggests the peak value of daily confirmed cases would waver around 105,000 counts in the last week of September 2020. The cumulative COVID-19 cases would account for approximately 105 lakhs at the end of December 2020. Conclusion: The exponential model unravels a shift and a modest decline in the growth of daily confirmed cases. The trends in R(t) show analogue with the trends in growth rates of daily confirmed cases. The study shows that the SARIMA model is suitable for projecting daily confirmed cases. The results shed light on the understanding of the trends and epidemiological stage of COVID-19 disease, in the cognisance of the peak. Contribution: This study based on moments of the distribution of the daily confirmed cases of COVID-19 disease unravels the uncertainty about the peak and curvature of COVID-19 disease. Keywords: COVID-19, SARS-CoV-2, Exponential model, ARIMA, Effective Reproduction rate, Growth rates, Pandemic