Thread by @drdagly

Ok. Educational thread. #COVID19 #vaccine #strains #Mutation

First a caveat. Until we have good data most of this thread is theoretical, but to keep you out of suspense, I believe that our current vaccines will protect us from evolving strains of coronavirus.

The reason for this is that the target chosen for these vaccines was its virulence factor, the thing that makes this normally annoying old virus deadly. The capsid spike protein that interacts with our bodies ACE2 receptor.

Viruses need a way to get into cells to infect them. Previous generations had spike proteins that opened doors on tissues of the throat and nose. The ensuing infection and inflammation is the stuffiness that we associate with a cold. You can survive a sore throat.

Viruses may not be smart, but they are fast and plentiful, and random mutations during billions of replication modified this key along the way. Most of these new keys would not turn in the cellar locks. These viruses failed to reproduce and disappeared along with their keys.

Some keys were improvements, fitting better into existing locks and opening the doors easier. Anyone who has had a poorly cut key knows how much jiggling and futzing it can take to turn a lock cylinder. These were more efficient and hence more infectious viruses.

Eventually a key was found not to just the throat, but to every part of the body, via blood vessels. This was pivotal. Now more cells to make more virus. That’s an evolutionary advantage... for the virus, but only if it doesn’t kill off its host.

These new variants, to remain problematic must maintain similarity to the original spike protein. It doesn’t have to be perfect but it has to be very close. Too different and the key no longer fits the lock. When that happens, the virus is relegated to its old ways. The throat.

We’ve seen this new variant B1.1.7 refine its key to better fit our locks, but it still fits the antibodies created by these vaccines well, and hence will be managed by the vaccine.

Any other modification to spike proteins that are drastic enough to not fit antibodies should also not fit the ACE2 receptor.

Now there is nuance to this. Just as receptor affinity influences infectivity, it will likely influence vaccine protection, and so these variants may reduce effectiveness of the vaccines, but this remains to be seen.

Overall, however the best thing we can do is continue with rapid vaccination to reduce population morbidity. In effect providing evolutionary pressure to push the virus back to its old ways, while allowing it to naturally attenuate.

Cuz in the end Rona doesn’t really want to kill us. That was just an unfortunate side effect. 🤔

Also full apology to virologists, immunologists and microbiologists, as my courses were taken years ago. And also my eternal gratitude. Please correct me ad lib!