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Tell you what NB you are on the ball with everything, i would like to sit down with you over a pint or two, i am not very good with written answers, don't take this post the wrong way
No worries - I just try to call it as I see it, based on reading actual virologists etc rather than people who may have medical qualifications but use them to push an agenda. Usually that means I'm a bit more cautious than average, but in the case of B.1.640.2 it seems to be getting hyped the other way.
The real lesson from B.1.640.2 is not the variant itself, but it emphasises how Africa has been rather forgotten during the pandemic. They've suffered less than many places because their population is so young, but they have relatively little vaccine coverage and so are getting hammered during the "mild" omicron wave. Couple that with the fact that both omicron and B.1.640.2 have "appeared" with lots of mutations, which implies they've been quietly mutating away without being spotted - you normally reckon on 2-3 mutations per month. That could mean a chronic infection in an individual with a weak immune system (eg from HIV), a series of infections in a human population that's not well monitored, or an animal reservoir.
Aside from getting more vaccines to Covax (the scheme to distribute to poor countries), one of the best things we could do is get a couple of young scientists over from places like Kenya and Nigeria, train them at our (absolutely world-class) sequencing labs, then send them home with a couple of sequencing machines and a freezer full of reagents. Would cost peanuts in the scheme of things and wouldn't just help the world keep tabs on new SARS2 variants, but HIV, Ebola and all sorts of other things.
do rabies, measels and smallpox viruses mutate enough to evade vaccination/effective treatment? Because smallpox has been vaccinated out of existence
I don't want to get too hung up on other diseases as they're all different in detail to SARS2, I just wanted to make the point that this "rule" of declining virulence is BS. It all depends on the detailed lifecycle of the virus. Immune evasion is a separate issue to inherent virulence. I don't know much about the genetics of measles or rabies but I would note that there is a small zoo of different strains that cause both rabies and measles which I assume is partly in response to vaccines, although AIUI neither has particularly good treatments other than vaccination.
Smallpox is the only human disease that we've managed to eradicate, and that took a really effective vaccine, great vaccine uptake and some favourable characteristics, like no animal reservoirs in the wild. The SARS2 vaccines are good but not that good, and what now look like multiple animal reservoirs means that we're probably never going to eradicate it.
If a virus is causing more serious disease and therefore introducing greater mortality won't severe government restrictions hamper its ability to spread in favour of a milder less serious variant that we are not so concerned about?
I know what you're getting at and in theory you have a point but in reality the world doesn't work like that, government restrictions aren't applied uniformly or consistently, in every country around the world and to the animal populations within them, not just humans.
I have read that mutations usually are a trade off of one ability against another, so its unlikely that a virus can spread much easier, evade vaccinations and become more lethal. Has vaccination and restrictions led to some evolutionary pressure?
The tradeoff thing applies more to "established" pathogens, but when a pathogen is new it still has quite a lot of freedom to improve without tradeoffs. SARS2 is still at the Model T stage where it has lots of room for improvement and is inferior in every way to eg a modern pickup truck. In time it will become "better" and more specialised, like a modern Transit van or Ferrari, which have to tradeoff between eg cargo capacity and speed/handling.
You've seen this with delta, which is much more transmissible but was still about as nasty as "classic" Wuhan virus. As I keep saying - SARS2 doesn't really "care" if it's more lethal or not, because it's spreading before the host gets sick.