Thursday, July 29, 2021

What you need to know about the Delta variant

Jonathon V. Last, Editor of The Bulwark tells us about Everything Delta. His report is based on a conversation between Bill Kristol and Ashish Jha.

Bill Kristol sat down to talk with Ashish Jha, who’s dean of public health at Brown. Their conversation is very much worth your time.

But there are a few bits I want to flag for you:

[T]he biggest thing about the Delta variant that I think has been a bit of surprise is just how contagious it is. It is way more contagious than any variant of this virus, and that really changes things. And it changes things in terms of how much population immunity you need. It changes things in terms of what the breakthrough infections are for the vaccinated… .

we are starting to see some data around the durability of the vaccines, at least as far as preventing breakthrough infections. And this is preliminary data from the UK, preliminary data from Israel, maybe a little data from the US, that as you get six, seven months out of vaccinations, you start seeing some more breakthrough infections, particularly in elderly people.

So what does it mean to say that the delta is “more contagious”?

So if you start with the original strain, the original Wuhan strain from last year, from 2019, 2020, the Alpha variant, which was the one originally from the UK, B117, that was a super contagious variant. If you remember back in March, April, we were like, “it’s a race between the variant and the vaccine.” We were trying to beat the Alpha variant. And that we thought was 50 to 70% more contagious than the original Wuhan strain.

This one is, and again, people have different numbers, kind of in the 60 to a hundred percent more contagious than the Alpha variant. All right, so what does that all mean? And how do you think about it? There are a couple of ways of thinking about it. One is, if you look at the amount of virus in the nose, throat of a patient with Delta variant, it’s about a thousand times more virus than what we saw with the previous strain. So it’s a lot more with a much higher viral load.

Another way people think about this is where the original Wuhan strain virus, the average person might have infected two or three people, about three people. The Alpha, we thought the average person infects four to five. The Delta variant now, the average person may be infecting six to eight. And if you think about exponential growth, 1, 3, 9, 27, 81, that’s pretty substantial growth. 1, 6, 36, three, four generations of spread and it’s massive, you just get to much higher numbers, much, much faster with the Delta variant.

Okay, so you combine the increased contagiousness of delta with the unexpected number of anti-vaxxers and what you get isn’t great. But the third piece here is the vaccines being slightly less durable than expected.

In general, the vaccines have performed better than initial expectations in just about every way, but the biggest unexpected bonus was the extent to which they cut down on transmission. The durability problem is the first time they haven’t overperformed. But whatever. If people need booster shots, that’s not the end of the world.

But when you add it all up, what does it look like going forward? Not great.

Three things—a much more contagious variant, fewer people vaccinated [than we hoped], and now some waning immunity—means this is a very different situation than we thought we were in a few months ago. This means the next few months are going to be pretty tough. A lot of Americans are going to get infected. A lot of vaccinated Americans are going to get infected. Most vaccinated Americans are going to do extremely well, the unvaccinated Americans are not going to do extremely well. And we’re in for a bumpy few months.

One last thing: Here’s Jha giving a pretty nice layman’s explanation for how being vaccinated works to help you avoid really bad outcomes with COVID:

the vaccine has, essentially think of it as, it’s an army, and it has two kind of main things. It has the antibodies, which are your active forces. They’re the ones that would protect you from getting infected. Then you have your reserves, the T-cells and the B-cells, and they kick in once an invasion has happened, once you’re infected.Three things—a much more contagious variant, fewer people vaccinated [than we hoped], and now some waning immunity—means this is a very different situation than we thought we were in a few months ago. This means the next few months are going to be pretty tough. A lot of Americans are going to get infected. A lot of vaccinated Americans are going to get infected. Most vaccinated Americans are going to do extremely well, the unvaccinated Americans are not going to do extremely well. And we’re in for a bumpy few months.

Your T-cells and B-cells are still doing fabulously well with the Delta variant, that’s why we’re not seeing a lot of hospitalizations and deaths among vaccinated people. But the problem is when the amount of virus that shows up is just much, much larger, because of this huge viral load, your antibodies can get a bit overwhelmed and that’s why we’re starting to see more breakthrough infections: you just don’t have enough antibodies and they do wane over time… .

So you’re having lunch with your friend indoors at a restaurant, your friend is unvaccinated and infected, what would your risks be if you were unvaccinated of picking up the virus from your friend, and then how much does the vaccine knock it down? And we think based on the best data that your vaccine knocks it down about 80, 90%, so that’s pretty good.

The problem is that when there’s very little infection in the community, it’s fabulous. But when you imagine that you’re having lunch with an infected friend every day, one of those times …

in May and June, I had lunch and dinner indoors with vaccinated friends several times and felt very comfortable doing so. And in the last 10 days, two weeks, when a friend reaches out for dinner, I’m like, “Let’s see if we can find an outdoor place to have dinner.” Not because I’m worried, because all my friends are all vaccinated, but I don’t know that I want to be in a packed restaurant where other people may be unvaccinated.

And here’s why, and this is really important, because people say, “Well, what’s the big deal?” I actually have had colleagues who’ve had breakthrough infections, and one of them had fevers for about three days, 103, felt pretty lousy. About a week later he was mostly back to normal, but just felt like he was kind of wiped out for a week.

And my thought was, “I don’t want that.” If I could avoid a week of my life being wiped out by an annoying viral infection, I don’t want that. So it’s not so much that I’m terrified that I’m going to die or get hospitalized. It’s easy enough to avoid and there’s a lot of Delta starting to spread the country, I think I’m going to stick with mostly being outdoors for a little while until this Delta surge subsides.

Be smart about this stuff.

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