<div><p>It's been more than a month since the Dasara-Deepavali-Chhath festivities and the Bihar elections that were feared to trigger a second wave of the pandemic. The fear was so great that Prime Minister Narendra Modi had to address the nation to warn of it. But the second wave hasn't yet arrived although there was barely any Covid-appropriate behaviour beyond the big cities. Even scientists are puzzled. What went right? </p><p><strong>Is it possible that the SARS-Covid-2 lost its virulence? </strong></p></div>.<div><p> It is unlikely that the circulating virus strain has changed much in terms of its virulence, which is biologically modest to begin with. There hasn't been enough selection pressure on it as yet for major changes in virulence to get selected.</p><p><strong>Maybe, enough people have been exposed to the virus without any disease, and the pool of the vulnerable has shrunk. </strong></p><p>This is the most plausible theory but there isn't enough data to back it up. The first ICMR sero-survey done in May-June showed a prevalence of just 0.73%. The second survey in August-September found a prevalence of 7.1%, a 10-fold jump. The current prevalence is likely to be about 20%. If the pool of susceptible people shrinks, the probability of a second surge also comes down. </p><p><strong>Is India doing enough testing?</strong></p><p>While the number of tests remains high, it's the distribution that matters. The question is are we testing people in places that matter as there is now evidence of the disease spreading to the hinterland. For instance, Bihar and UP account for more than 20% of the tests carried out nationally, but they produce very few positive cases. The tests are largely concentrated in urban areas while experts suggest that people in villages should also be tested, taking a syndromic approach. </p><p><strong>Is the data from the states suspect? </strong></p><p>Yes. States are trying to keep their numbers down to look good. This is why test numbers vary greatly from place to place and time to time. Besides, less sensitive rapid-antigen tests are being done, again quite variably. All of this is likely to confuse the data quite a bit and contribute to the pool of people who are exposed to the virus but have escaped the radar.</p></div>
<div><p>It's been more than a month since the Dasara-Deepavali-Chhath festivities and the Bihar elections that were feared to trigger a second wave of the pandemic. The fear was so great that Prime Minister Narendra Modi had to address the nation to warn of it. But the second wave hasn't yet arrived although there was barely any Covid-appropriate behaviour beyond the big cities. Even scientists are puzzled. What went right? </p><p><strong>Is it possible that the SARS-Covid-2 lost its virulence? </strong></p></div>.<div><p> It is unlikely that the circulating virus strain has changed much in terms of its virulence, which is biologically modest to begin with. There hasn't been enough selection pressure on it as yet for major changes in virulence to get selected.</p><p><strong>Maybe, enough people have been exposed to the virus without any disease, and the pool of the vulnerable has shrunk. </strong></p><p>This is the most plausible theory but there isn't enough data to back it up. The first ICMR sero-survey done in May-June showed a prevalence of just 0.73%. The second survey in August-September found a prevalence of 7.1%, a 10-fold jump. The current prevalence is likely to be about 20%. If the pool of susceptible people shrinks, the probability of a second surge also comes down. </p><p><strong>Is India doing enough testing?</strong></p><p>While the number of tests remains high, it's the distribution that matters. The question is are we testing people in places that matter as there is now evidence of the disease spreading to the hinterland. For instance, Bihar and UP account for more than 20% of the tests carried out nationally, but they produce very few positive cases. The tests are largely concentrated in urban areas while experts suggest that people in villages should also be tested, taking a syndromic approach. </p><p><strong>Is the data from the states suspect? </strong></p><p>Yes. States are trying to keep their numbers down to look good. This is why test numbers vary greatly from place to place and time to time. Besides, less sensitive rapid-antigen tests are being done, again quite variably. All of this is likely to confuse the data quite a bit and contribute to the pool of people who are exposed to the virus but have escaped the radar.</p></div>
