New Variants of SARS-CoV-2 are Inevitable

Walter Reed Army Institute of Research 

People who study the evolution of viruses published an op-ed in yesterday's New York Times about the likely future evolution of SARS-CoV-2. Here are some high-points of the essay.

First, viruses evolve to survive and reproduce better. That is just what they do. There is no reason to think SARS-CoV-2 will stop evolving.

Second, there are still plenty of pathways available for further evolution. The writers reckon there are "nearly 2000 other ways the 201 targeted amino acids could could mutate and still be able to attach to human cells."

Third, the evolutionary pressure on the virus is to become better at spreading. It can do this by becoming more contagious and/or better at evading the immune system. They say it is "remarkable" how good this virus has been at responding to that pressure.

Fourth, how much more transmissible the virus could become is unknown. There is not an infinite capacity: "a cheetah can’t evolve to be infinitely fast, and SARS-CoV-2 won’t become infinitely transmissible," they say.  Some viruses, like measles, are more contagious; others like influenza are less contagious. 

Fifth, the bottom line is that COVID-19 is here to stay:

Taking all this together, we expect SARS-CoV-2 will continue to cause new epidemics, but they will increasingly be driven by the ability to skirt around the immune system. In this sense, the future may look something like the seasonal flu, where new variants cause waves of cases each year. If this happens, which we expect it will, vaccines may need to be updated regularly similar to the flu vaccines unless we develop broader variant-proof vaccines. 

Those variant-proof vaccines are in the works. In December I blogged about a promising Walter Reed Army Institute of Research effort that had concluded phase 1 trials and was moving on to phases 2 & 3. 

Unfortunately, I'm not able to get a sense of where they are in that process. Yesterday they released a new study in preprint, but from what I can tell it involves animal models rather than new human trials. Hurry up guys!

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