Covid-19 R-value under one almost all over India, best week since pandemic began

R-value estimates are a measure of an epidemic’s ability to spread

The week in which India reached the grim milestone of registering one crore Covid-19 cases is probably the best week since the pandemic started in India in terms of the R-value estimates – a measure of an epidemic’s ability to spread.

Not only is the R down for India, pegged at 0.86, but almost none of the states with the maximum number of active cases have an R-value more than 1. Among the big cities, only Mumbai and Pune have R greater than one and even for Mumbai, the very recent data seems to suggest that R may have just gotten below one.

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This is the finding of a model being run by Sitabhra Sinha, a mathematician at the Institute of Mathematical Sciences, Chennai who has been tracking the pandemic since it started.

“It is probably the best week after Covid-19 started in India in terms of the R estimates for the country as a whole and for various states. It is even marginally lower than the previous minimum of 0.88 that occurred in late October,” Sinha told DH.

R or reproduction number is a measure of an epidemic’s ability to spread. If the R is 1.9, it means 10 infected persons can transmit the disease to 19 individuals. For an epidemic to be contained, the R-value has to fall below one and remain at that level consistently.

In its latest run with data up to December 16 for India and December 14 for the states, the model threw up R-value under one for all big states like Maharashtra (0.71), Kerala (0.95), West Bengal (0.85), Karnataka (0.74), Delhi (0.78) and Tamil Nadu (0.96).

Among the metro cities, Bangalore fared the best with an R of 0.66 followed by Kolkata (0.81) and Chennai (0.95) – a clear sign of the epidemic in recession in such urban conglomerates.

With 25,152 new infections, the total number of active cases slumped to 3.08 lakh on Saturday even as India’s Covid-19 positive cases crossed the one-crore mark. The death toll stands at 1,45,136 of which 347 were added in the past 24 hours.

During the worst phase of the pandemic, India was registering more than 90,000 cases daily reaching up to 98,000 once. But since then, there was a steady decline in the number of daily cases and death tolls notwithstanding the Diwali-Dussehra-Chhath festivities as well as Assembly and local body elections in several states where there was considerable mingling among people.