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COVID and Evolution: It was always going to get more contagious and less deadly

Since I am a biologist and know how viruses evolve, I never paid much attention to the scary pronouncements from the authorities that the latest variant of SARS-CoV-2 coronavirus is worse than the first strain, is a scary “game changer,” and is a justification for a new round of lockdowns, etc., etc..

The problem is, I am a biologist and I know how evolution works. You need to think about this from the standpoint of the virus. What does the virus want in an evolutionary standpoint? The same as any other form of life: it wants to reproduce and spread its numbers. It does not care whether it kills us. In fact, it is somewhat contrary to the virus’s interests to kill us. It needs a person it infects to at least stay alive long enough to spread the virus to a few new hosts. If it kills the person right away, there is not enough time for him to spread the infection. Also, if it were really deadly, we would be more likely to take societal measures to reduce the spread of the virus, which the virus does not want.

It is in the evolutionary interest of the virus to become more contagious but not more deadly. Mostly the virus should not really care whether it gets more deadly, but it is at least mildly in its evolutionary interest to become less deadly.

So I expected—and any competent biologist should have expected—as this epidemic went on that the COVID virus would evolve to become more contagious but not more deadly and probably less deadly.

At the same time, there are limits to how contagious it can get. I will predict it will never get more contagious than the common cold. The common cold viruses have had the same evolutionary interest as COVID or influenza viruses of wanting to spread as widely as possible and they have succeeded. The common cold is about 3 to 4 times more contagious than influenza in that about 15% of the population is infected with flu or influenza in a given year but about 50% or more gets the common cold. These viruses have had 100,000 years to evolve to infect humans and spread as efficiently as possible, and that is what they have achieved—infecting about 50% of the population each year, even with us taking no great measures to avoid getting a cold. I am confident in predicting that the COVID virus will never do better than that.

This evolutionary standpoint is also useful in thinking about the claims that were made that COVID might spread asymptomatically (it does not). The reason we sneeze and cough when we have a cold or flu is that the virus wants us to. The viruses have evolved to cause us to sneeze and cough because sneezing and coughing emits virus particles and allows the virus to infect other people. The virus has no inherent interest in making us unhappy or feel lousy except in spreading the infection. If it could spread without us sneezing or coughing, that would be preferable because we would be unaware we were infected and thus more likely to continue to go out and others would not keep their distance from us and not know they should wash their hands more if they have been around us. But that strategy does not work to spread infection. If it did, that is the strategy the upper respiratory tract viruses would employ and we would not be coughing and sneezing. So as a biologist, I always knew it was almost certain that asymptomatic people infected with COVID did not spread it or did not spread it to any significant extent.

This evolutionary viewpoint brings me to the Omicron strain in my next post.

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