06-10-2021, 10:08 PM
(06-10-2021, 09:33 PM)tomh009 Wrote:(06-10-2021, 07:44 PM)danbrotherston Wrote: I don't know if we'll need that, I'm not sure anyone does. The beginning of the pandemic, we seemed to see very little change in the virus, but now we seem to be seeing a lot more variants. I'm not sure why, I would have thought variants would be driven mostly by spread, but I didn't think spread was significantly higher now than in the first year of the pandemic. Perhaps our data is better and we are seeing variants more clearly but I don't think so.
In any case, I don't know how different the variants are from each other, especially in terms of their ability to evade our immune defenses (vaccination driven or otherwise), and how that compares with the flu.
Essentially, the virus RNA mutates constantly, just like the human DNA does (well, the generational cycle for the viruses is just wee bit faster, but the concept is the same). Most of the mutations end up being either meaningless or actually harmful to the virus, making it unviable. But some combination of mutations have staying power and end up being more "energetic" and viable than their predecessors. And these end up being identified as the variants. (There have been many more variants than these four but they have ended up not spreading as far.)
Challenging conditions (in human bodies, in environment, competing viruses etc) will often result in different mutations succeeding rather than the original. Even the vaccines can cause the virus to mutate to survive. A mere spread will generate more mutations (because there are billions of more viruses that may mutate) and variants, but a spread with difficult conditions will do so at an accelerated pace.
All the variants (to date!) still use the same infection mechanism, and that's why the vaccines still work, even if slightly less effectively. The likelihood is that the variants will evolve further, to the point where a revised vaccine will be needed in order to improve the efficacy. Hopefully not in the next six months, though, so that we can get our initial vaccinations completed, here and worldwide.
I mean, I understand the essential mechanism of evolution here. But I'm not really seeing what conditions changed between early last year, and late last year, early this year to cause more variants. I wouldn't think the vaccine was widespread enough in that timeframe, and the level of spread and containment policies have been more or less the same.
What I meant about how this compares with the flu is that each year the flu virus has mutated somewhat from previous years (and different strains are more or less prevalent), which is why we have new vaccines every year. But we also know that the previous flu vaccines are somewhat effective for new flu variants each year that the old vaccines were not specifically designed for--which is exactly what we are seeing with COVID. What I don't know is how effective the previous flu vaccine is with new variants. For COVID we actually have some numbers on this. But if we had this number for flu vaccines (and I feel like it must be known, or at least knowable), we could start to get an understanding of how likely we are to need a new vaccine every year based on what policies we already use for flu vaccines.