New Delhi: India’s effective reproduction number ‘R’ for Covid-19 — a key parameter to measure the rate of spread of infection — has dipped slightly to 1.08 from last week’s 1.09.

At this rate, the country is likely to face a burden of over 15 lakh active cases by 8 October.

Only three weeks ago, the overall R value of India dipped to 1.04, which was the lowest the country had recorded since the Covid-19 pandemic began. However, around 3 September, the value increased to 1.09 as worst-affected states began to see a rise in infections.

Sitabhra Sinha, a researcher at the Institute of Mathematical Sciences in Chennai who has been tracking India’s R value, had told ThePrint that with R at 1.09, India will cross 12 lakh active cases by September-end.

On Wednesday, India recorded 9,95,933 active coronavirus cases. A total of 82,066 people have died.

Chhattisgarh continues to have the highest R value of 1.35 and is among the worst-affected states. It has remained the same since August.

R value as well as R0 (basic reproduction number) are an estimate of the number of people a patient can infect.

While R0 is calculated at the beginning of an epidemic, when the entire population is assumed to be susceptible to a disease, R changes with time and takes into account the fact that some individuals are protected from the illness — either because they have developed immunity or due to social distancing measures.

For India, the R0 was calculated to be about 1.83 in April. An epidemic is considered to be under control when the R value remains below 1 consistently.

R value up in Delhi, West Bengal, Kerala

Delhi has seen a consistent rise in its daily case numbers and therefore its R value has also increased in the past few weeks. The national capital has gotten marginally worse this week. The city’s R value increased to 1.26 this week, from last week’s 1.22.

While the national capital’s R value had dipped below 1 for a couple of weeks till 4 August, it increased to 1.09 around 18 August, up from 0.66 in the beginning of the month.

West Bengal, which had an R value under 1 for the last three weeks, has also seen an increase in the infection transmission rates. This week, the value increased to 1.01 from last week’s 0.93.

Kerala’s R value increased to 1.07 from 0.88 last week. Assam, which reported a sharp increase of 1.22 around 3 September from 0.80 the week before, now has an R value of 1.05. Last week the value was close to 1.

Andhra Pradesh’s R value has increased marginally to 0.95 this week from 0.94 last week.

States that dipped

The good news is that several high-burden states have seen a dip in their R values.

Maharashtra’s R value saw a slight dip to 1.17 this week from 1.18 last week.

Telangana saw a significant dip in its Covid transmission rates this week, reducing to 0.92 from last week’s 1.06.

Tamil Nadu and Odisha both reported a significant decline as well. For Tamil Nadu, the value reduced to 0.93 this week from 0.98 last week. Meanwhile, the R value for Odisha dropped to 1.11 this week, after seeing a steady value of 1.13 in the last two weeks.

Meanwhile, Karnataka and Uttar Pradesh have the same R value as last week – 1.13 and 1.10 respectively.

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