Last week, as several installments in this column had pointed out, was going to be crucial for India in terms of how the trajectory of the coronavirus disease would unfold in the country. It was to show if India would also see the festive effect seen in almost every other country where mass festivities and celebrations resulted in an increase in cases weeks later. Diwali, perhaps the largest festival in India, was in mid-November, and if the number of daily cases was going to increase due to the holidays, family gatherings, and travel associated with the celebrations, last week is when this would have turned up. The week has come and gone. We are now on December 7th and India seems to have escaped the holiday effect.
The daily case numbers for the first six days of last week, Monday through Saturday, were: 31,182; 36,421; 35,414; 36,653; 36,212; and 36,439. That equates to a six-day average of 35,387. All these numbers are from the HT panel. The average is the lowest India has seen in four and a half months. That would take us back to the third week of July.
These numbers lead to two interesting questions.
The first question is why did India not see the peak that the United States and the countries of Europe saw after similar celebrations and meetings?
The obvious answer, and as it is obvious, there is also a high probability that it is the wrong answer, but more on this shortly, is that Diwali coincided with the end of the first wave of infections in India (or the beginning of the second ). And because of this, he did not see an increase in cases two weeks later, even though people violated social distancing rules or took more risks when traveling.
This doesn’t add up because if nothing really changed in the virus’s ability to infect people (it didn’t; for example, there was no sudden mutation that made it less virulent), and if people really took more risks than they did previously, there should have been an increase in infections. This is exactly what happened in the United States after Labor Day and what experts say is happening now after Thanksgiving. And this is exactly what happened in European countries.
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This suggests that the answer could be that the chain of infection breaks more frequently and easily than before, and despite violations of social distancing norms, something that is only possible if the virus, as it seeks to jump from person a person, find more people who are immune to it. It’s hard to say this for sure in the absence of regular and widespread testing for SARS-CoV-2 antibodies, blood tests popularly called sero-surveys, but the answer seems to be in that direction.
The reason for the absence of a post-Diwali increase, then, could be a combination of two complementary factors: masking, social distancing, and other safety protocols that some still followed (and continue to); and a relatively high level of exposure to the virus in the population, resulting in an equally high level of protection.
This does not suggest that India has achieved herd immunity or is close to doing so. Nor is it an endorsement of any approach that focuses on achieving herd immunity. It is mere scientific conjecture that seeks to explain why India has not seen a post-Diwali surge.
Also read: Covid-19 cases in the US remain above 200,000 for the fourth consecutive day
The second question (which somehow stems from the first) is about the waves in which the coronavirus disease affects populations. We know that a wave begins to wane when testing, tracing, and isolation begin to reduce the chance of infection, and it increases as life returns to normal, as commercial, recreational and social activities increase, but also there is a natural path to infection. For example, at a certain level of infection (or exposure), the number of new infections will begin to decrease, gradually at first and then abruptly. So, based on understanding these (the level of activity and the rate of infection), can the timing of the next wave be predicted?
That’s for the experts to answer.
Post script: With India escaping the post-Diwali surge, if its current coronavirus disease trajectory remains at the plateau it is at until the end of the month, it is likely (a low but significant probability) that the second wave in India will be less. . intense, not only compared to the US and Europe, but also compared to the first wave of the country, because if all goes well, India could start vaccinating people in the first of its six priority groups ( prioritized in terms of when they will get the vaccine) early next year.
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