Read on Twitter
A thread on #SARSCoV2 mutations and what they might mean for the #COVID19 vaccination and immunity, in which I predict it will take the virus a few years to mutate enough to significantly hinder a vaccine. 1/12
I& #39;m writing this thread because I have a bunch of mentions talking about 100s of "strains" and no ability to vaccinate against them. I want to clarify scientific usage of strain vs mutation. 2/12
RNA viruses such as influenza mutate very rapidly. The molecular machinery they use to replicate in the body is highly error prone. 3/12
If you follow a transmission chain in which one person with flu infects another person and they infect another person and so on, you& #39;ll find that the virus mutates about once every 10 days across its genome. 4/12
Almost all of these mutations will have little to no effect on virus function. Evolution weeds out the mutations that "break" the virus and mutations that make a virus replicate better are extremely rare. 5/12
For influenza, the major driver of evolution is immunity. Mutations will occasionally appear that cause people& #39;s existing immunity to no longer protect as well against a newly emerged mutant virus. 6/12
This is why the strain used in the influenza vaccine needs to be updated by the @WHO every year. Here you can see evolution of influenza H3N2 over the past 12 years and the amount of "antigenic drift", ie evolution relevant to vaccines and immunity. https://nextstrain.org/flu/seasonal/h3n2/ha/12y?c=cTiterSub">https://nextstrain.org/flu/seaso... 7/12
Importantly, this evolution takes takes place over years. When pandemic swine flu emerged in 2009, it took the virus a solid 3 years before we saw any evidence at all of antigenic drift. https://nextstrain.org/flu/seasonal/h1n1pdm/ha/12y?c=cTiter">https://nextstrain.org/flu/seaso... 8/12
If I had to guess, I would predict that #SARSCoV2 will behave similarly to existing seasonal coronaviruses in its ability to mutate to avoid vaccines and immunity. 9/12
Here we see that seasonal coronaviruses may behave similarly to seasonal flu in which frequent mutations to spike protein (the protein targeted by immunity) are observed ( #tab2">https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.81662-0 #tab2,">https://www.microbiologyresearch.org/content/j... https://www.nature.com/articles/srep11451).">https://www.nature.com/articles/... 10/12
Here& #39;s @firefoxx66& #39;s analysis of seasonal coronavirus OC43 where we see frequent mutations to spike protein. https://nextstrain.org/community/nextstrain/CoV/Betacoronavirus1?d=tree,entropy&p=full">https://nextstrain.org/community... 11/12
So, my prediction is that we should see occasional mutations to the spike protein of #SARSCoV2 that allow the virus to partially escape from vaccines or existing "herd" immunity, but that this process will most likely take years rather than months. 12/12
