COVID-19: This dip in growth rate is quite interesting

On Apr 14, 2020

NEW DELHI: A statistical analysis of active coronavirus cases has revealed a significant decline in reproductive number of SARS CoV 2 virus in India, possibly due to the lockdown and social distancing.
The factor to arrive at how many people could catch a disease from a single infected person in a population that hasn’t been exposed to the disease before, is R0, also called R-naught. If R0 is below one, the epidemic eventually would die out. Above one, it keeps growing, possibly exponentially.

An analysis by the Institute of Mathematical Sciences, Chennai showed that R0 for the novel coronavirus was 1.83 from March 5 to April 5 in India but dipped to 1.53 from April 6 to April 13. Globally, R0 for SARS CoV 2 has been between 2 and 4.“A close analysis of the R0 graph pattern suggests that there has been a statistically significant lowering of the rate at which the number of cases has been growing,” said Sitabhra Sinha who led the team of analysts.

“Assuming this is a genuine new trend, I guess we can attribute it to the lockdown, as in any case we were expecting the response to the lockdown to be manifested after about two weeks from its beginning. This is because for the first two weeks of the lockdown period, the increase in numbers would be mostly due to people who had gotten infected before the start of the lockdown,” he said. “While a few states like Telangana do seem to be showing a similar kind of reduction in the growth rate starting April 6, which is consistent with what we see nationally, there is no such reduction in the data from Maharashtra,” he added.