India’s Covid R value falls to lowest so far at 0.92, West Bengal & Rajasthan concern areas

India's R value continues to remain below 1 because most of the 12 worst-affected states have R values below 1.

A woman undergoes a Covid-19 test in Delhi | Photo: ANI

New Delhi: India’s R value — a key parameter to measure the rate of an infection’s spread — has decreased to the lowest ever value of 0.92 this week from last week’s 0.95. The value has remained below 1 for the past four weeks.

R value represents the number of people one patient can infect. A number below 1 means the number of active cases is declining.

According to Sitabhra Sinha, a researcher at the Institute of Mathematical Sciences in Chennai, R continues to be below 1 because most of the 12 worst affected states with the highest active Covid cases have R values below 1. The exceptions are West Bengal, Kerala, and Rajasthan.

“Maharashtra, the state having the highest number of active cases, has R down to 0.84 from 0.94 the week before,” Sinha told ThePrint.

“The state with the second highest number, Karnataka, also managed to bring down R to less than 1 very recently — from around 1.06 to 0.89,” Sinha said, although he added that whether this will be a lasting trend remains to be seen.

While Kerala, the state with the third highest number of active cases, continues to have R higher than 1, it has reduced from 1.29 last week to 1.08 this week.

“So this is all encouraging,” Sinha said.

West Bengal and Rajasthan look worrying

West Bengal, however, continues to have an R above 1. Apart from Kerala and Rajasthan, West Bengal is the only state among the 12 worst-affected states in terms of active cases to have R above 1.

But more worryingly, over this week, its R value has marginally increased to 1.07 from 1.05 last week, Sinha pointed out.

“While this may look like a very small increase, it will result in the active cases increasing exponentially which will soon make these numbers enormous,” he said. “Coming at the heels of the festival season when presumably people will be in public places in large numbers, this is alarming.”

Rajasthan has emerged again in the worst-affected 12 after spending several weeks out of the list. “This is because it has consistently had R over 1 for more than a month,” Sinha said.

“Initially the number of active cases was low — and so the R value of 1.06 didn’t ring any alarm bells. But even a small excess of R value over 1 would have major consequences if it continues to be higher than 1 for long enough,” he said.

Other high burden states

The R value for Assam was at 0.96 last week, which increased to just over 1 this week. Tamil Nadu, Chhattisgarh and Odisha all saw slight increase in their R values, but all these states remain below 1.

For Tamil Nadu, the R value increased very slightly from 0.96 last week to 0.97 this week. Meanwhile, for Odisha it increased from 0.81 to 0.87.

Chhattisgarh saw a significant increase from 0.89 to 0.99 this week.

Meanwhile, the value for Telangana fell from 0.90 to 0.88 this week. Andhra Pradesh and Uttar Pradesh have the same R values as last week — both are at 0.87

Major metros

Among the metros, Delhi continues to have R less than 1 since 18 September. However, the R value has risen to 0.94 from 0.82 last week.

Similarly, Mumbai has maintained R value under 1 since 3 October, but the value increased over the last week from 0.84 to 0.90.

Pune continues to fluctuate with R again down to 0.68 this week from 1.04 the week before.

However, Chennai, Kolkata and Bengaluru all have R values greater than 1.

Chennai’s value fell from 1.08 to 1.06 while Kolkata maintained the same value of 1.11 over the last two weeks. Bengaluru’s R value rose from 1.08 to 1.16 this week.