Updated: April 21, 2022 7:17:34 am
India’s effective reproduction number (R-value) for Covid-19, an indicator of how quickly a disease is spreading in the population, has increased to over 1 for the first time since mid-January, during the third wave of the pandemic.
The R-value, which saw a steady increase over the last few weeks, was 1.07 for April 12-18, according to Sitabhra Sinha, a researcher from Chennai’s Institute of Mathematical Sciences who has been tracking the country’s R-value since the beginning of the pandemic. It was 0.93 the previous week.
An R-value of 1, which signifies that every infected person is passing on the infection to at least one person on an average, is a key threshold after which cases begin to rise.
Asked whether this could signal the beginning of the fourth wave, Sinha said: “It’s too early to say whether it will be a wave; there have been a couple of instances, for example in last August-September, when the R-value was higher than 1 but it was not termed a wave. An R-value of greater than 1 doesn’t mean that it is a wave, but yes, in the last 10 days or so, we have seen an increase.”
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The current increase in R-value is mainly driven by the spike in Covid cases in Delhi, Uttar Pradesh and Haryana in the north and Karnataka in the south. The R-value for the week ending April 18 stood at 2.12 for Delhi, 2.12 for Uttar Pradesh, 1.04 for Karnataka and 1.70 for Haryana.
On Wednesday, Delhi reported 1,009 new cases, one death and 5.70 per cent positivity rate. In view of the rising cases, the Delhi government has decided to make masks mandatory again, with a fine of Rs 500 in case of a violation. Earlier this week, Uttar Pradesh and Haryana made masks mandatory in districts near Delhi. While the Delhi Disaster Management Authority (DDMA) has decided not to shut schools, it will come up with separate Standard Operating Procedures (SOPs) for them.
Cities like Mumbai and Chennai have also reported an R-value of over 1 — 1.13 for Mumbai, 1.18 for Chennai and 1.04 for Bengaluru.
At the height of the Omicron-driven wave, the country’s R-value had risen to its maximum so far of 2.98 (December 30, 2021-January 10, 2022). “The R-value for the third wave was the highest. The perception of threat for the third wave might be low in the minds of people — probably because there were fewer deaths — but the number of people getting infected was very high,” said Sinha.
“The value for India we have estimated at present is roughly what the R-value was (1.08) between February 14-March 11 last year — i.e., just before the onset of the second wave when it rose to 1.37 on March 9-April 21, 2021, before decreasing to 1.10 (April 29-May 7) and finally to below 1 by May 9 (R: 0.98),” said Sinha.
With 2,067 new cases being reported in the last 24 hours, India’s active case load stands at 12,340; the weekly positivity rate is 0.38 per cent.
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