Coronavirus | Opeds and editorials

Caution and optimism: On preventing the third wave

India, with the second highest number of cases globally and third highest deaths, is seeing about 50,000 cases being added every day. Though on a decline, the second wave is far from over and several States are relaxing lockdown restrictions, which, experts say, may be seeding the ground for a potential third wave . In this context, a mathematical modelling study led by the scientists at the Indian Council of Medical Research (ICMR) and the Imperial College London, shows a wary optimism. Will a potential third wave be as devastating as the second, the scientists attempt to find out, and their answer is ‘no’. For that to happen, a trifecta of “extreme scenarios” has to converge. One, over a third of those who have been infected in the past year must entirely lose their immunity. Second, an emerging variant of the virus must have a reproductive rate (R) over 4.5, or every infected person should be passing on the virus to at least four to five others. And finally, both of these must occur almost close to when the second wave has almost extinguished itself. This is beyond the transmissibility seen so far.

A third wave could be significantly buffered by expanding vaccination. Were vaccines to be rolled out in a way to cover 40% of the population, with two doses until August, it could reduce symptomatic incidence by around 55%. Less than 20% of Indians have got at least one dose of the vaccine and only 4% fully vaccinated. The Centre proposes to vaccinate all adults — about 94.4 crore — by the year end. India’s States, which have at various times dealt with unprecedented crises during the tragedy, now have an estimate of what is needed to tide out their peak phases. In that light, the ICMR’s projections can help with ensuring the minimum number of supplies and other infrastructure in the event of an uptick. However, it should not be forgotten that this is after all a modelling study. None of India’s eminent institutions, in the early part of the year, forecast the scale and intensity of the second wave. There is also the vexing matter of breakthrough infections, that is those contracting the infection in spite of being vaccinated. Sporadic studies in India suggest that this percentage of infection is small, though there is still no clarity on the real-world effectiveness of vaccines in the light of variants such as Delta and Delta Plus. There is also, so far, no theoretical limit on how infectious the coronavirus can become. The ICMR’s analysis thus should not be taken as a forecast but rather a guidance and a reminder that along with vaccination, masks, avoiding crowds and physical distancing will remain the main defence against the virus for the foreseeable future.

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Printable version | Jul 4, 2022 11:23:30 pm |