Re:Prior Omicron infection protects against BA.4 and BA.5 va...
by bonzini on Sunday July 24, 2022 @05:05PM
(#32217722)
In the first countries where Omicron spread, such as South Africa, it was first detected in young people where vaccination was very low. And just like Delta or Alpha it started to diverge before mass vaccination was a thing. The article you linked even suggests Omicron may have developed in mice, which are obviously not vaccinated, so the mutations would not be driven by selective pressure against vaccination.
Evading vaccination could very well be why it was so fast to spread in mostly-vaccinated populations in Europe and North America, which happened "faster than any previous versions" as the (very interesting!) article you linked says at the very beginning, but the variant was more fit anyway.
https://www.nature.com/articles/d41586-022-00215-2
"Omicron forms a stronger grip on ACE2 than do previously seen variants3. It is also better at evading the virus-blocking ‘neutralizing’ antibodies4 produced by people who have been vaccinated, or who have been infected with earlier variants [..] At some point [..] something happened to help Omicron explode, maybe because the progress of other variants — such as Delta — was gradually impeded by the immunity built up from vaccination and previous infection, whereas Omicron was able to evade this barrier."