NEW DELHI: Testing levels in several states have gone down during periods when their positivity rate - the proportion of tests yielding a positive result -- is increasing. This is the opposite of what you would expect, which is that states ramp up testing as their positivity rate increases.
In Delhi, for instance, between June 3 and June 11, the seven-day average of daily tests went down from 6,540 to 5,001 even as the positivity rate kept rising from 18.3% to 27.7%. Delhi incidentally now has the highest percentage of tests turning positive, over a quarter of them.
Delhi had another phase of constant decline in the seven-day average of tests between May 16 and May 26, when it fell from 6,660 to 4,675 tests. In both phases, the reduction in tests was at a time when the positivity rate was climbing.
There are no states with positivity rates in double digits barring Delhi and Maharashtra. In Maharashtra, the seven-day average for tests steadily declined from May 29 to June 6 from 14,497 to 12,764. It has since increased to 14,236 tests by June 11, the cut-off date for this comparison. Again, the reduction happened even as there was an increase in the positivity rate, which went from 17.6% to almost one out of every five tests being positive.
Gujarat, the state with the fourth highest Covid-19 cases in the country, saw three such phases, though one was not very significant. The two significant phases were the ones between May 8 to 15 when the average declined from 5,230 to 3,210 tests a day and the May 22 to May 30 phase when the average steadily declined from 6,386 to 3,959 tests a day, even as the positivity rate rose from 7.5% to 9.7%. For Madhya Pradesh, that phase was May 18 to May 26 when the average steadily declined from 5,161 to 3,576 tests a day.
In Odisha, average daily tests have been steadily declining from May 24. From 4,659 tests for that day, it came down to 2,798 for June 11, a period in which the positivity rate went from 1.6% to 4.6%. In many other states, the seven-day average of daily tests came down while the positivity rate went up just marginally, as in Rajasthan, Haryana and Uttarakhand.
Data for West Bengal, Uttar Pradesh, Jharkhand and Andhra Pradesh do not show such phases of reduction in testing. However, the tests per lakh population rates for West Bengal, Uttar Pradesh, Jharkhand and Bihar are so low, that there is hardly any scope for further reduction.
India is among the four worst hit countries and its testing rate of 3.8 tests per thousand is far lower than Russia's 95, the US's 66 and the UK's 54. What is worrying is that despite this, some states are reducing the number of tests even as the positivity rates goes up.