JOIN USAmid the Covid gloom, models suggest a sliver of hope for Delhi and Maharashtra; India’s R value improves
Though it may be early days, multiple mathematical models suggest a sliver of hope for Delhi and Maharashtra where the Covid-19 numbers have been dropping while the R-value – a mark of the Covid-19 virus’ ability to infect - for the country has also improved from what it used to be in April.
In one such model developed by researchers at the University of Michigan, USA the R value for Delhi stands at 0.9 on May 5 as against 2.3 on April 12. Similarly, for Maharashtra, it was 0.99 on May 9.
R or reproduction number denotes how many healthy individuals will get the infection from a Covid-19 positive person. An R value of 1.9 means 10 Covid positive persons will spread the infections to 19 others. For the epidemic to shrink, the R value has to come down below 1.
“The curve for Delhi shows that public health interventions work and they save lives. We have a lot more work to do, people are still suffering and in tremendous pain, but after Maharashtra, Delhi is also looking hopeful. However, we cannot declare premature victory, never again!” tweeted Bhramar Mukherjee, professor of epidemiology and biostatistics at the University of Michigan.
Her model received corroboration from another disease tracking model developed by Sitabhra Sinha at the Institute of Mathematical Sciences, Chennai. It shows Maharashtra has been showing an R value of less than one for more than two weeks now (starting from April 24). Mumbai is showing a decreasing trend for its active cases since April 11.
“It would seem that Maharashtra, and especially Mumbai, is on the road to recovery. For India as a whole, most trustworthy models have suggested a peak around the middle of May, although with large uncertainties about that date, and it currently appears as if daily cases may have stalled around 410,000,” Gautam Menon, a professor of biology and physics at the Ashoka University told DH.
Sinha said the national R value trend improved riding on better R value from Maharashtra. Although it is still above one, the rate of growth has slowed down considerably.
The University of Michigan model came out with an R value for India as 1.18 on May 5 as compared to 1.61 on April 18. In Sinha’s model, the R value for India was 1.31 between March 9 and April 21, which has now come down to 1.09 between April 30 and May 8.
But Sinha also cautioned against early celebrations citing the examples of Madhya Pradesh and Chhattisgarh – two states that showed a decrease in R but a subsequent rise, reversing the gains.
Madhya Pradesh went from R of 1.35 (between Mar 4-Apr30) to 0.92 (between Apr 28-May 3) but then again rose to 1.26 (between May 5-9). Similarly the R for Chhattisgarh went from 1.56 (Mar 10-Apr 6) to around 0.93 (between Apr 18-28) and then again rose to values above 1 during Apr 29-May 6.
Experts are also concerned about a reduction in the daily tests, which can miss out infections resulting in an artificial slowdown. “The growth appears to have slowed down a bit but we need to test more,” tweeted Mukherjee.
“The state of testing is dismal and test positivity is too high across India. So this sense of a drop in the number of cases may be illusory,” noted Menon.