Covid-19 in India: What you need to know today

India's surging second wave of coronavirus disease infections is unlike anything the world has seen thus far. It is a surge that makes the pace of the US's brutal third wave seem tortoise-like.

Numbers across the first four weeks of April highlight this. April 1: 81,413 cases, 468 deaths. April 8: 131,830 cases, 802 deaths. April 15: 219,913 cases, 1,156 deaths. April 22: 332,394 cases, 2,255 deaths. The number of active cases has soared in this duration, from 0.62 million on April 1 to 0.98 million on April 8 to 1.57 million on April 15 and 2.43 million on April 22.

Cases have risen 308% between April 1 and 22; deaths by 382%; and active cases by 292%.

It isn't surprising that this deluge has overwhelmed the health care systems even in most large cities. Even the best systems will likely collapse under the pressure created by the rate of growth of cases (and the consequent rate of growth of those that need hospitalisation). Everything (tests, hospital beds, oxygen, medicines) is in short supply, and health care workers are stretched to breaking point (many are falling ill too, although anecdotal evidence suggests that those who have been fully vaccinated are mostly recovering without hospitalisation).

The question everyone is asking is: How long will this last? Surely, India cannot continue to report in excess of 300,000 cases for very long?

One number that may provide some clues on this front is the positivity rate.

This is the number of people testing positive expressed as a proportion of those tested (the whole thing is expressed as a percentage). The assumption here is that most states are following the Union government's instruction of making sure at least 70% of their tests are the accurate RT-PCR ones, and also that these tests can identify mutant strains of the Sars-CoV-2 virus that are clearly responsible (at least in part) for the current surge in cases. As tests increase, the positivity rate should come down. In general, any positivity rate in excess of 5% and rising is worrying; anything in excess of 10% and rising is alarming.

India's positivity rate for the week that ended on April 22, was 18% (and also higher than the corresponding number for the previous week, so it is rising). The number indicates that the country is probably not testing enough people, and that the number of cases is only likely to increase.

A digression is in order here.

The surge requires a change in India's testing protocol. Rapid Antigen Tests are not accurate, and while this column has argued against their use indiscriminately, it has recommended that they be used "wherever time is a constraint" (Dispatch 159, September 16, 2020). Since RT-PCR tests are backlogged (at every stage, from specimen collection to the actual testing) for days, states should mandate the administration of rapid antigen and RT-PCR tests together. Those that test positive in the rapid test can be isolated or hospitalised depending on their need; those that test negative merely have to be isolated while they wait. The main problem with rapid antigen tests is the high number of false negatives (in contrast, the test is very accurate in identifying cases with high viral loads), so it's easy to see how this approach can reduce delays in testing, and ensure that at least some of those infected with the virus get the treatment they need earlier than they otherwise would have.

But back to the question of how soon things will get better, a reading of positivity rates across some of India's most populous states suggests this won't happen for at least a few weeks, may be more.

For instance, Uttar Pradesh's positivity rate for the week ended April 22 was 14.2%, Maharashtra's, 24.5%, West Bengal's, 19.4%, Bihar's, 9.2%, Tamil Nadu's, 10%, Madhya Pradesh's, 23.5%, Karnataka's, 13.6%, Rajasthan's, 18.3% , Punjab's, 10.6% and Kerala's, 17.2%. And all rates are higher than their corresponding ones for the previous week.

Sure, states can always resort to managing the numbers instead of the pandemic as some seem to already be doing (the low positivity rate of Gujarat is at odds with reports emerging from the state), but if they continue to report numbers as honestly as they have until now (however honest that may be), we are looking at a situation where cases will continue to grow till well into May.

If the current trend continues, India may well be the first country to see 400,000 daily cases, perhaps even 500,000. And even at a 1% case fatality rate, that will translate into 4,000 and 5,000 deaths. This is what governments must prepare for as they seek to manage the second wave (the time to contain it is long past), but if they do the right things now, they can still prevent the third wave.