2nd wave of virus outbreak in monsoon, warn scientists

New Delhi: The trajectory of COVID-19 cases could have plateaued and might even fall for some weeks after the lockdown is lifted but India is likely to see a second wave in late July or August with a surge in the number of cases during the monsoon, say scientists.

The timing of the peak will depend on how India is able to control physical distancing and on the level of infection spreads after restrictions are relaxed, they said.

"It looks apparent that the trajectory of daily new cases has reached a plateau and eventually it will take a downward fall, maybe for some weeks or even months," Samit Bhattacharya, associate professor at the Department of Mathematics, Shiv Nadar University, told PTI. "Still, we may get a surge of new cases of the same coronavirus and this will be considered a second wave," Bhattacharya explained.

The second epidemic may come back in late July or August in the monsoon, although the peak timing will depend on how we control social distancing during that time, he said.

Rajesh Sundaresan, professor at Bengaluru's Indian Institute of Science (IISc), agreed.

"Looking at the new cases in the past few days, it seems the growth of new daily infection is much slower than earlier. This apparently indicates that we might have reached at the plateau of the growth curve," Bhattacharya said.

"The lockdown is currently upon us. It has given us valuable time. Let us test, trace, quarantine, isolate, practice better hygiene, search for a vaccine, etc. We should do these anyway, and these are being done. When and how to lift the lockdown is going to be a difficult decision to make," said Sundaresan.

"It's clear that it's going to be phased. What our team is focusing on is to come up with tools to help the decision makers assess the public health impact of various choices," he said. According to the experts, infectious diseases spread via contact between infectious and susceptible people. In the absence of any control measures, an outbreak will grow as long as the average number of people infected by each infectious person is more than one.

Once enough people are immune there will be fewer people susceptible to the infection and the outbreak will die.

However, when an outbreak is brought under control by social distancing and other interventions, it is possible only a small proportion of the population will have been infected and gained immunity, they said.

This means enough susceptible people may remain to fuel a second wave if controls are relaxed and infection is reintroduced.