Background: The second wave of COVID-19 is affecting most of the world . The scenario is very grim in India where the daily count on April 15 , 2021 itself is double of the first peak . The epidemic evolution there is quite complex due to regional inhomogeneities . In this paper, we characterize the virus spread in the ongoing second wave in India, as well as study the dynamical evolution of epidemic from the beginning of the pandemic .
Methods: Variations in the effective reproduction number (Rt) in India are taken as a quantifiable measure of the virus transmissibility and are compared with those of other countries where the second wave is already over . Further, characteristics of COVID-19 spread are analyzed for Indian states by estimating test positivity and case fatality rates . Finally, forecasts and actionable inputs are provided based on mathematical and epidemiological models .
Results: Effective reproduction number for almost every state in India has value greater than 1 indicating the presence of the second wave . An exponential fit on recent data indicates that the infection rate is much higher than the first wave however the case fatality rate is lower . Preliminary estimates with the SIR model suggest the peak for the second wave to occur in mid-May 2021 with daily count exceeding 0.35 million .
Conclusions: The spread of the second wave is much faster than the first wave . Hence, quick and effective administrative intervention is needed to arrest the rapid growth of the epidemic.