How different will Covid's 3rd wave be from first two? What India government says
Given the high levels of circulating virus, the third wave of coronavirus is inevitable but the time scale is not clear, the government's principal scientific advisor K Vijay Raghavan said, explaining how the biology of the virus has changed between the first and the second wave
Variants are only one factor of the huge second wave of the Covid-19 that is sweeping the country now, the government's principal scientific advisor K Vijay Raghavan said on Wednesday. As new variants of a virus are natural, the existing variants will make way for new variants which may or may not be more virulent, but variants should not make any difference in people's primary approach to combat Covid-19, which should consist of maintaining social distancing, the expert said. While in 2019 and 2020, the virus continued to be a generalist, like a key that can be fitted into many locks, the virus in 2021 became much fitter and efficient as it is trying a "hit and run lifestyle" to gain entry to the human body. In the coming days, the virus will become more efficient as immunity, vaccination are building adaptive pressure on the virus.
Here is what the government said about the various waves of the pandemic:
> The first wave halted as a combination of a standing level of immunity in the population and cautionary steps.
> The second wave started because new opportunities for the spread of the infection come up. When the guard drops, the immunity is sometimes not enough to stop the infection from spreading.
> Many people get infected until a new threshold of immunity is reached.
> Such a second wave is typically smaller than the first wave. Such a second wave was expected. However, multiple parameters can change in small amounts and add up to a second wave which is much larger than the first wave.
> Such a larger second wave with such ferocity was not predicted.
> Immunity, developed after the first wave, is not widespread. The number of people who remained unaffected because of cautionary steps taken in the first step may have been large. Immunity can also fade. Someone infected earlier can get reinfected but we know that the protection is still very high after eight months.
> In 2019, when the virus emerged, it was a generalist. It could infect many mammals and was not a tightly human-adaptive virus. The lineage continued for a long period. In the second phase, which started in October 2020, the virus became fitter. "It was a key that could fit many locks," the expert said adding that with the increase in the transmission, the key became more refined.
> In early 2021, a very large number of people all over the world had been infected. As the immunity increases, the virus does not have the opportunity to grow. But it sees that there are pockets it can go through and therefore there's selection through evolution for the viruses to be more efficient in transmission. In the second phase, efficiency has been selected because of already present immunity in the population. The virus will thus find new routes.
> A phase 3 is inevitable given the high levels of circulating virus, but the time scale is not yet clear.
> On immunity getting eroded by the evolution of SARS-CoV-2, experts said it is positioned somewhere between measles and influenza. Measles immunity never gets eroded while that for influenza gets depleted rapidly. The viral evolution of SARS-CoV-2 is somewhere in between but will change.
