India coronavirus numbers explained: Positivity rate begins to decline, relative stagnation in new detections.

INDIA: India Coronavirus Cases Numbers: After rising steadily for the last three months, the positivity rate reached a peak of 9.01 per cent on August 9, after which it has begun to decline. It has come to 8.72 per cent now.

India Coronavirus Cases: For the first time since May, the overall positivity rate in the country has begun to decline, indicating that, out of those who are being tested, far lesser number of people are being found infected now than earlier.

After rising steadily for the last three months, the positivity rate reached a peak of 9.01 per cent on August 9, after which it has begun to decline. It has come to 8.72 per cent now.

The dip in the positivity rate is significant because it could mean that the spread of the disease in the population is slowing down. This would certainly be true if the tests were being carried out randomly. However, most states are still relying on targeted testing, meaning only those who are showing symptoms of the disease or who are close contacts of an already infected person, are being tested. A shift to more random testing could also trigger a decline in positivity rate, because far greater number of people are likely to be detected positive in targeted testing.

Another reason for the drop in positivity rate could be that, as recent serological surveys have shown, a large number of people have already been infected with the virus, without them ever knowing about it. As this number grows, and in some places it seems to have gone beyond 50 per cent of the population, the positivity rate is likely to come down, because some of these previously infected people might also be getting included in the tests, and they would turn out to be negative.

The decline in positivity rate is also getting correlated with a relative stagnation in the number of new infections being detected every day. This number has hovered around mid-60,000s for two weeks now, slightly longer than it has done in any other range recently. For example, the new detections remained in the 50,000s for just eight days before more than 60,000 new cases began to get detected. Similarly, just about a week each was spent in the 30,000s and 40,000s.

There is not just a relative stability in the 60,000s but the number of new detections has also dropped into the 50,000s several times during this time, though mainly after the weekends when the test numbers usually go down by a significant amount.

The drop in the positivity rate has come at a time when the number of tests being carried out every day has increased significantly. When the number of daily new detection of infected cases had first crossed the 60,000 mark in the first week of August, around 6.5 lakh samples were being tested every day. Now, about 8.5 lakh tests are being conducted every day. Usually, higher number of tests results in higher detection of positive cases. The fact that the daily detection has continued to remain relatively stagnant in the mid-60,000 range also points to the same trend, that the spread of the disease could be slowing down.

These trends could open up discussion on whether the level of infection in the Indian population has reached a stage from where further transmission of the virus would begin to slow down. The recent serological survey in Pune found more than 51 per cent of the people already infected with the disease. When the spread of the disease reaches that level, there are more people who are infected than uninfected. Because of lesser number of people who can potentially get the infection, the rate of transmission, or the speed with which the disease spreads, would come down. It might still be early days, but the possibility that this has begun to happen on a limited scale, at least in some places, cannot be ruled out. This is exactly how the concept of herd immunity comes into play.

On Tuesday, more than 64,000 new cases were detected across the country, taking the number of confirmed infections to 27.67 lakh. More than 20 lakh of these, about 73.6 per cent, have already recovered from the disease, while the death count has reached close to 53,000. More than 1,000 deaths were reported on Tuesday.