For the first time in India’s outbreak since March, the Covid-19 transmission rate has increased.
India’s Covid-19 reproduction number, or R, which estimates the number of people infected by one already infected person, was on a steady decline from 1.83 for months since March 4. However, in the first week of the second unlocking phase in July, the rate has shown an increase for the first time, research by the Institute of Mathematical Sciences in Chennai shows.
Having an R less than one is the goal of health authorities, as it signifies a flattening of the curve.
The R is currently at 1.19, which means that each infected person on average infects 1.19 people, according to Dr Sitabhra Sinha, a scientist at the institute.
“It usually takes 10 days to two weeks for any effect to show up as increased or decreased case numbers. So, I would say that this increase we are seeing probably has its origin in events that happened around mid-June or slightly later,” he said. “The bottom line is that right now we are in the situation we were in in May and early June, and the further decrease we saw in late June was not sustained or improved upon.”
Delhi has shown significant strides, from an R number of 1.25 between June 13-16 to a curve that is now around 1. For a few days starting June 21, Delhi had an R slightly above one. Sinha called the curve “sub-exponential”, meaning not growing exponentially for some time now.
Haryana is also showing similar signs. The only other time a heavy-caseload state showed such positive trends was in April to mid-May when Tamil Nadu flattened the curve substantially.
In March, the virus was being transmitted to 1.83 people on average in India while the rate was 2.14 in Wuhan and 2.73 in Italy. Between April 6 and 11, India’s R dropped to 1.55. Subsequently, it dropped to 1.49 and then 1.2 by early June, as the country began to relax the lockdown in a phased manner.
The transmission rate continued to decline into June, reaching 1.11 by June 26. However, after a month of unlocking, the transmission rate has picked up between July 2 and July 5 to 1.19.
The highest R numbers are in the south in Karnataka (1.66), Telangana (1.65) and Andhra Pradesh (1.32). Previously fast-growing states have slowed down, such as Gujarat at 1.15 and West Bengal at 1.1. “The current increase in R can most probably be attributed to the high R for some of the southern states,” Sinha said.
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States like Assam and Rajasthan are not currently consistent enough to estimate for, Sinha added.
Total active cases could reach around 6 lakh by the end of the month, Sinha’s modelling shows. Maharashtra could have over 1.5 lakh active cases by July 21, and Tamil Nadu 1 lakh.
An analysis of district-wise data from state bulletins by The Indian Express shows that cases and deaths are gradually becoming less concentrated in the top 10 districts. While 46 per cent cases were in the top 10 a month ago, it is 41 per cent now. Similarly, 59 per cent of all deaths were in the top 10 districts, and it is 54 per cent now.
A total of 448 districts have seen at least one Covid-19 death, up from 391 two weeks ago.
New names have entered the top 10 districts with the most cases: Gurgaon and Indore have been replaced by Bengaluru and Palghar. However, the list of top 10 districts with the most deaths has been consistent over time.
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