Covid-19: What you need to know today
More tests (9.66 million till Tuesday evening) than any other state barring Uttar Pradesh and Bihar. The use of reverse transcription polymerase chain reaction (RT-PCR) tests alone, unlike UP and Bihar which have largely used rapid antigen tests. Around 127,000 tests per million of the population. These are some of Tamil Nadu’s Covid-19 metrics — and they are impressive.
The southern state has seen 714,235 Covid-19 infections (till Tuesday), the fourth highest in the country after Maharashtra, Andhra Pradesh, and Karnataka; and recorded 10,983 deaths, the third highest in the country after Maharashtra and Karnataka. Its case fatality rate of 1.53% is marginally higher than the country’s 1.5%, and its cumulative positivity rate of 7.4% is almost the same as the country’s 7.57%. These are some more of Tamil Nadu’s Covid-19 metrics — and they aren’t all that impressive.
Yet, as the first wave of the coronavirus pandemic winds down in India, I’d like to believe Tamil Nadu is the state that has managed the health crisis the best. Here’s why.
The first reason is testing.
For a state with a population of around 76 million to test 127,000 people per million is an achievement. India’s overall number is 79,141 tests per million. And Tamil Nadu continues to test aggressively. Significantly, the state relies exclusively on the gold standard RT-PCR molecular tests. I have written extensively about the perils of the indiscriminate use of rapid antigen tests; their false negative rate is around 50%, which means they miss infections in around half the people carrying the virus. India’s 79,141 per million number is built on the back of rapid antigen tests. UP and Bihar rely on them; even Delhi uses far more of them than it should be doing. Tamil Nadu’s dependence on RT-PCR tests means its positivity rate data is much more credible.
The second is the trajectory of positivity rates over time in the state.
The positivity rate is simply the number of people testing positive expressed as a percentage of the number of tests conducted. Tamil Nadu’s positivity rates started high (when very few tests were being conducted), dipped as the number of tests increased, then rose again as the infection soared, then fell and plateaued with consistently high testing, and finally started ebbing. The seven-day average has been below 5% for two weeks, and the daily number at or below 5% for the past 10 days. The World Health Organization said in May that a rate below 5% for two weeks meant the pandemic was under control. To be sure, this benchmark needs to be achieved even as testing remains consistently high and the right kind of tests are used (Tamil Nadu satisfies both conditions).
Both these factors are reflected in the state’s current Covid-19 metrics. On October 27, Tamil Nadu saw a mere 2,522 cases — 5.85% of all cases recorded that day. Even the seven-day average of daily cases has fallen — it was 2,866 on October 27. After a long plateau through August and September (and a peak in July), the trajectory of daily cases has fallen through October.
The same is reflected in the number of deaths. On October 27, Tamil Nadu registered 27 deaths (seven-day average: 35), way down from the peak seen in August. Like the daily case numbers, the death toll plateaued through much of September before beginning to fall in October.
Other states would do well to peruse the charts accompanying this column carefully — this is how a successful Covid-19 management strategy looks (without using the wrong kind of tests or controlling case numbers through inadequate testing).
Does this mean case numbers will not rise again in Tamil Nadu?
Definitely not. They could. In May, crowding in a vegetable market in Chennai caused a spike. Earlier this month, frightening videos of crowds in a Chennai saree shop (since sealed by the local administration) did the rounds. Any such foolish behaviour could result in an increase in cases.
And does this mean Tamil Nadu will remain insulated from the inevitable second wave?
That’s very unlikely, but the state’s administrators have a proven strategy to follow.
That’s more than can be said for many other states or Union territories.