Thread by @ASlavitt

COVID Update: The debate on whether Americans should be offered 3rd shots as boosters in not a simple one.

But it does present a very clear choice. 1/

Our best understanding of the immune response to an m-RNA vaccine is important to this question. 2/

How:

1- 1st dose creates a big antibody response, made bigger by a 2nd
2- That response allows the immune system to act fast in the face of an invasion of the virus.
3- That quick response is key to preventing symptoms particularly when there’s a high viral load like Delta 3/

4- That antibody response wanes over time so in the case of Delta it provides less punch. The 2 factors together create more symptomatic infections for vaxxed ppl
5- But even as it wanes, our body remembers w memory B cells & T cells 4/

6- Memory B cells & T cells are how we remember to fight off measles even though we have a shot as a kid
7- But this response is slower than when you have high antibodies already
8- Therefore over time we are able to still blunt infections before they get serious w memory B & T 5

9- All of this means that over time, without a booster we have string protection against hospitalization & death but are more able to get colds & other effects
10- Some of these effects are mild and pass but occasionally we know they can be long lasting 6/

You can hear all about what happens when symptoms last here if you want. 7/

podcasts.apple.com/us/podcast/in-…

So (choice A) if you think the purpose of a vaccine is to prevent hospitalization & death, that may happen quite well without a boost.

(Best to speak with humbly by saying “may” of “may for now”) 8/

Now if instead you prefer a vaccine to prevent symptoms & also significantly reduce transmission (choice B), that’s what a boost would do. 9/

So who wouldn’t prefer choice B? It’s obviously better. And certainly better for people with lower immune protection or more exposure to the virus (nursing home, health care workers, immunosuppressed).

But before you say “Choice B!”, there’s a catch. 10/

The catch is that if we choose Choice B, we increase the odds of future variants.

Here’s how: variants are threatened by the vaccine & will mutate the more unvaccinated people exist. And if we keep giving the same people the vaccine we won’t get there. 11/

Right now 10 countries are using 90% of the vaccines. If those (rich) countries kept reusing new vaccine supply every 6 months, we will perpetuate this issue.

With many countries at 1-2% vax.

And the moral challenge of saying us first. And second. And third. Then you.12/

One expert tells me that if we can accelerate global vaccination by 9 months from the current G7 target we can dramatically reduce the potential for the more deadly variants. 13/

The other reality is the US needs to lead on this decision to get other wealthy countries to follow. 14/

So the way it all shakes down for me is: if we think the job of the vaccines should be to protect against severe illness & the development of more dangerous mutations, then we would boost only most at risk people. 14/

If we want the vaccine to protect us against symptoms and transmissions (in the first world), then we do so at the cost of others around the globe & the cost of future variants. 15/

The political realities favor the kind of choice we’ve been seeing made all pandemic. Protect well off first to the nth degree before we consider others (see: essential workers) 16/

The WHO calls on us morally not to boost. Many epis are in that camp when it comes to fighting the pandemic.

But neither of them call the shots. 17/

Money equals lives here. And the same country is writing the check for the vaccines that would be used here & in Africa.

The US. 18/

Only tough choices exist in a world of scarcity.

The public should understand the policy choices here & the implications of what we decide not just on us, not just in the pandemic, but on everyone. /end

And this is where the US appears to be headed.

washingtonpost.com/health/2021/08…