India’s Covid R value crosses 1 once again, Maharashtra, Punjab & Karnataka see increase too

India's R rose to 1.02 this week, which is concerning because any epidemic will continue growing as long as the R remains above 1.

Health workers take samples from outstation passengers for Covid-19 tests, following a rise in cases, at Chhatrapati Shivaji Maharaj Terminus, in Mumbai, on 17 February 2021 | PTI

New Delhi: India’s Covid-19 effective reproduction number or R — an indicator of how fast the infection spreads in a population — has crossed 1, increasing from 0.93 last week to 1.02 this week.

This is concerning because any epidemic will continue growing as long as the R remains above 1.

At the beginning of the pandemic, India’s R for Covid-19 was 1.7, which increased to as high as 1.83 before it fell after the lockdown.

Around 24 September, the country’s R fell below 1 for the first time, dropping to 0.93. However, around 27 November the R had briefly risen to more than 1.

Since then R had been around 0.92 for several weeks. But this week, the value crossed 1 once again.

According to Sitabhra Sinha, a researcher at the Institute of Mathematical Science in Chennai, between 17 and 21 February, India’s R was estimated to be 1.09.

“More recently, it has come down a bit to 1.02,” he added.

All major states’ R more than 1

The increase is primarily driven by the fact that half of the top 16 states, in terms of active cases, have R over 1.

“Maharashtra is now back at the top of the list of states having the highest number of active cases,” said Sinha.

Last week, Maharashtra’s R was already above 1. This week, it has further increased to 1.18.

Karnataka’s R was 0.97 last week, but is now more than 1.

Meanwhile, Punjab now has the fifth-highest active cases in the country and its R value also rose to 1.23 this week from 1.04 last week.

Madhya Pradesh and Gujarat both have R values at 1.14, while Haryana’s R is 1.16.

Sinha noted that even among states that that have R less than 1, the values are fairly close to the threshold.

“This means that the decrease in active cases has considerably slowed down for these states,” Sinha said.

Chhattisgarh, Assam, Telangana, Rajasthan and Delhi all have R values very close to one. However, due to the limitations of the mathematical model used to calculated R, Sinha cannot provide a robust estimate of the value when it is too close to 1.

Kerala’s R value declines

Kerala is the only state that showed a significant decline in R, from 0.92 last week to 0.87 this week.

According to Sinha, if the state managed to keep its R below 1, its active cases could reduce. At present, Kerala has the second-highest active cases in the country.

“While both West Bengal and Tamil Nadu have R below 1, the cities of Kolkata and Chennai have R above 1,” he added.

All major cities now have R above 1. For Mumbai, R value went up from 1.11 last week to 1.23 this week. Pune, however, saw a small decrease — from 1.38 to 1.33 this week.

Chennai’s R went up to 1.11 this week from 1.02 last week, while Bengaluru’s infection rate went up from 1.03 to 1.07.