If India Sees a Third Wave Of Covid-19, How Will We Identify
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Having failed to adequately prepare for the second wave of coronavirus infections, officials and health authorities are now routinely warning people of the possibility of a third wave. It started earlier this month with the Principal Scientific Advisor K VijayRaghavan calling the third wave inevitable even though its timing could not be predicted. Local administrations and some hospitals have already begun ramping up their infrastructure in anticipation of a fresh surge in cases after a few months.

~ What is a wave in an epidemic?

The term epidemic is used generically to describe the rising and declining trends of infections over a prolonged period of time. The growth curve resembles the shape of a wave. Historically, the term wave used to refer to the seasonality of the disease. Several viral infections are seasonal in nature, and they recur after fixed time intervals. Infections rise and then come down, only to rise again after some time.

Covid-19 has continued relentlessly for the last one-and-a-half years, but in every geography, there have been periods of surge that have been followed by a relative lull. In India so far, there have been two very distinct periods of surge, separated by a prolonged lull. Smaller regions within a country, a state or a city, for example, would have their own waves.

~ So, how would one identify a third wave, if it comes?

The third wave currently under discussion refers to a possible surge in cases at the national level. The national curve seems to have entered a declining phase now, after having peaked on May 6. In the last two weeks, the daily case count has dropped to about 2.6 lakh from the peak of 4.14 lakh, while the active cases have come down to 32.25 lakh, after touching a high of 37.45 lakh. If current trends continue, it is expected that by July, India would reach the same level of case counts as in February. If there is a fresh surge after that, and continues for a few weeks or months, it would get classified as the third wave.

~ Will the third wave be stronger?

There has been some speculation about the third wave being even stronger than the second. However, this is not something that can be predicted. Usually, it is expected that every fresh wave would be weaker than the previous one. That is because the virus, when it emerges, has a relatively free run, considering that the entire population is susceptible. During its subsequent runs, there would be far lower number of susceptible people because some of them would have gained immunity.

This logic, however, has been turned on its head in India’s case. When the number of cases began declining in India after mid-September last year, only a very small fraction of the population had got infected. There was no reason for the disease spread to have slowed down, considering that such a large proportion of the population was still susceptible. The reasons for the five-month continuous decline in cases in India is still not very well understood.

~ But is it inevitable?

The third wave is a distinct possibility. It is likely to come, although the scale or timing is not something that can be predicted. But it is not inevitable. As mentioned, VijayRaghavan, the Principal Scientific Advisor, also modified his remarks, clarifying that it could possibly be avoided if people continue to take strong measures. It’s also possible that this time, the fresh wave will be indeed much smaller than the previous one, so that it inflicts much less pain and can be managed more efficiently.