Covid-19: R-value drops below 1 in mid-September as cases decline

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R-value, which reflects how rapidly coronavirus pandemic is spreading, dropped to 0.92 by mid-September after spiralling over 1 by August-end, according to researchers.

However, the R-values of major cities, Mumbai, Kolkata, Chennai, Bengaluru, are over 1. The R-value of Delhi and Pune are below 1.

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

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

"The good news is that India's R has continued to be less than 1, as is that of Kerala and Maharashtra, the two states having the highest number of active cases," said 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, 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.

The R-value value between September 4-7 was 0.94, 0.86 between September 11-15 and 0.92 between September 14-19.