R-value drops as spread of Covid slows down

10:50 PM Sep 21, 2021 | FPJ Bureau

New Delhi: The R-value, or reproductive number, for COVID-19 in India dropped from 1.17 in August-end to 0.92 in mid-September, indicating that the spread of the infection across the country has slowed down, according to researchers. However, the R-values of some major cities -- Mumbai, Kolkata, Chennai and Bengaluru, -- exceed 1. The R-value of Delhi and Pune is below 1.

The good news is that the R-values of Maharashtra and Kerala are finally below 1, giving much-needed relief to these two states with the highest number of active cases.


The R-value was 1.17 at the end of August. It declined to 1.11 between September 4-7 and since then it has remained under 1.


"Again, the pan India R continues to be less than 1," pointed out Sitabhra Sinha of the Institute of Mathematical Sciences, Chennai. Sinha is leading a team of researchers who calculate the R-value.

According to the data, the R-value of Mumbai stands at 1.09, Chennai 1.11, Kolkata 1.04 and Bengaluru 1.06.

The Reproduction number or R refers to how many people an infected person infects on average. In other words, it tells how ''efficiently'' a virus is spreading.

After the devastating second wave that saw hospitals and health infrastructure being overwhelmed by the patients infected with SARS-CoV2 coronavirus, the R-value started to decline.

During the March-May period, thousands of people died due to the infection, while lakhs were infected.

When the second wave of the coronavirus was at its peak, overall, the R-value in the country was estimated to be 1.37 between March 9 and April 21. It declined to 1.18 between April 24 and May 1, and it further dropped to 1.10 between April 29 and May 7.

Between May 9 and 11, the R-value was estimated to be around 0.98 and then 0.82 from May 14 to May 30. The R-value from May 15 to June 26 was 0.78. However, it increased to 0.88 from June 20 to July 7.

The R-value value between September 4 and 7 was 0.94, 0.86 between September 11 and15 and 0.92 between September 14 and19.

According to the Health Ministry, the recovery rate currently stands at 97.75 per cent. The weekly positivity rate (2.08 per cent) has been less than 3 per cent for the last 88 days.

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