24/07/2021
The simple take-home: vaccines may be causing the prevalence of the variants of concern to rise, so please don’t blame unvaccinated people for being “variant factories.” (Let’s not cast blame on each other at all and all respect each other’s personal medical decisions.)
DETAILS:
This graph is from a paper that claims to show that unvaccinated people are responsible for the rise in variants of concern.
The orange line shows the prevalence of mutations in the parts of the spike protein that are targeted by antibodies. While it was rising from the beginning, it took off like a rocketship starting in December of 2020.
What happened in December 2020?
This is when the vaccines were released.
It seems straightforward that the vaccines are creating the selective pressure that is causing the prevalence of mutations to shoot through the roof. The evidence is completely circumstantial though, so *could* have other explanations.
Strangely, the authors even state, "The rate of B cell epitope mutations has sharply increased, starting December," but they never attempt to explain the significance of that month.
Within this study, they also took a small number of people with COVID, some vaccinated, and some not. The unvaccinated had more mutational diversity, while the vaccinated had a higher rate of the alpha variant, which is of concern because it has a 50% increased rate of transmission. 83% of vaccinated had alpha, but only 60% of unvaccinated. This seems consistent with the vaccines exerting selective pressure for alpha, though the study is too small to conclude anything.
It seems impossible to accept the claim from the abstract that "The societal benefit of mass vaccination may consequently go far beyond the widely reported mitigation of SARS-CoV-2 infection risk and amelioration of community transmission, to include stemming of rampant viral evolution."
Selective pressure is not the only factor in evolution, but it is probably needed to make a single virion within a person dominate the population of virions to the point that the person can meaningfully spread it in the first place. An intermediate level of immunity that is strong enough to favor certain mutations but not strong enough to clear the virus is a major part of what creates selective pressure. Notably, one hypothesis is that immunocompromised patients are the source of variants, because they have an enduring hard-to-clear infection that keeps spreading, and treatments such as convalescent plasma exert the selective pressure.
The sharp spike since December in mutational prevalence is circumstantial evidence, but it's impressive and hard to ignore.
Here's the paper:
https://www.medrxiv.org/content/10.1101/2021.07.01.21259833v1
Here's a different paper discussing the role of intermediate immunity:
https://www.nature.com/articles/s41577-021-00544-9
Here's a paper on immunocompromised people and convalescent plasma:
https://jamanetwork.com/journals/jama/fullarticle/2779850