Covid concerns: That 23.5% of Delhi had Coronavirus isn’t all bad news

If the sero-survey has thrown up a much higher number, it is because Delhi is not testing enough.

That nearly a fourth of Delhi’s population is infected with the Covid-19 virus—23.5% according to the latest sero-survey—is bad news since, till now, most believed the number infected were much lower; the testing data so far had revealed that 1.2 lakh Delhiites were infected, and the sero-survey has pushed that up to 43.4 lakh immediately. Indeed, the 23.5% number is also higher than the 15% some newspapers had reported as the results of the sero-survey. This suggests Delhi, at least, is well into ‘community transmission’; it is, of course, odd that the official press release should say that ‘only 23.48%’ of people are infected.

The cumulative ‘case infection rate’ for Delhi—the number of infections divided by number of tests—has been hovering around 15% over the past week or so, and a little higher at 16.8% at the end of last month. If the sero-survey has thrown up a much higher number, it is because Delhi is not testing enough. Before testing in Delhi was ramped up significantly in the second week of July to over 20,000 per day, it was abysmally lower at sub-5,000 per day till May 26, sub-7,000 till mid-June and between 16,000-23,000 per day between June 27 and July, the period during which the sero-survey was conducted. Also, an increasing share of tests are of the rapid antigen tests (RATs) variety, which tend to throw up inaccurate results, rather than the more reliable RT-PCR tests.

The silver lining, though, is that the virus seems to be far less potent than originally anticipated. The official numbers of those hospitalised and dead are relatively small; with 3,663 persons having died, the casualty rate, in the context of nearly five million infected, is 0.08% instead of the 3% or so that the conventional tests throw up. Even hospitalisation rates have come down from around 25.1% using the reported data to around 0.7% if the same number of hospitalised is to be divided by the sero-survey’s number of 43.4 lakh persons. But, even if the sero-survey suggests Covid-19 is less virulent than was believed, it doesn’t mean Delhi is out of the woods. The data on hospital beds, ICUs, etc makes it clear that, no matter what the infection rate, the capital was getting overwhelmed a few weeks ago. Things look more comfortable after the massive ramping up of capacity, but if infection levels keep rising, things could turn around again. Also, not testing enough means the infected continue to spread the infection, and patients reach the hospital too late to be saved.

The problems with low levels of testing are reflected in the vicious resurgence of infections in Bengaluru. A month back, India’s IT capital was bragging it had just over a 1,000 infections. An empty boast, as they are at 33,229 today, and by mid-August, they could be nudging 1.4 lakh. Testing levels, fortunately, are up from around 2,500 per day a month ago to 15,000 now, but positivity levels have jumped to 14.4%; this was 5.5% a month ago. This is a lesson for cities that are still not ramping up testing, like Mumbai, where it is still hovering close to 6,000 a day, not much higher than the 4,265 tests a month back. Unless we know the extent of the problem, we can hardly deal with it effectively.