Tracking R value: Mumbai, Bengaluru and Kolkata record a rise

Even though a drop in India’s R-value or effective reproduction number for COVID – from 0.93 last week to 0.91 this week – comes as sign of relief, several metropolitan cities are still reporting a higher value ahead of the festive season.

R value or reproduction number, which is the average number of infections a primary case will generate, is used to gauge how fast an infection spreads among a population. The R value should be below 1 for the pandemic to recede.

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According to reports, cities like Kolkata, Bengaluru, Mumbai and Delhi have seen a slight spike in their R values over the last week.

Kolkata, which will witness Durga Puja festivities this week, saw an increase in its R value from 1 on September 29 to 1.06 on October 6. Similarly Bengaluru’s R value increased from 0.99 to 1.05 and Mumbai’s rose from 0.95 to 1.03 during the same time frame, Sitabhra Sinha, a researcher at the Institute of Mathematical Sciences told The Print.

Delhi too witnessed a spike in its COVID reproduction number – from 0.92 last week to 0.95 this week – while Pune’s R value increased from 0.82 to 0.96 in a week’s time.

Many states, however, have seen a slump in their R values.

Kerala’s R value dropped from 1.04 last week to 0.85 this week, while Tamil Nadu whose R value was above 1.02 for the past two weeks saw it slump to 0.98 this week.

While Maharashtra’s R value fell to 0.89 from 0.95 last week, Odisha’s dropped to 0.88 from 0.91 last week. The same for Andhra Pradesh came down to 0.85 from 0.92 last week, while the northeastern state of Mizoram also saw its COVID reproductive number fall to 0.94 from 1.1.

Even though Kolkata has seen a spike in its R value, West Bengal’s number has been steady at 0.96 for the past three weeks, multiple media reports report said.

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Meanwhile, the R value has remained unchanged in the states of Assam (0.92), Telangana (0.94) and Karnataka (0.94) for the past one week.

“Things can switch very quickly from good to bad and back again in smaller regions – because of the higher degree of variability when you are dealing with smaller populations – so it’s difficult yet to say whether we are finally seeing the end-game,” The Print quoted Sinha as saying.

The country on Wednesday logged in 18,833 fresh cases and 278 COVID-19 fatalities. The active number of cases has been pegged at 2,46,687, the lowest in 203 days, while the total tally stands at 3,38,71,881.

So far, over 91 doses of the COVID-19 vaccine have been administered across the country. This includes 66,38,07,388 first doses and 25,16,58,438 second doses.