COVID Transmissions for 4-2-2021

Six months of vaccine follow-up: safe AND durable

Apr 02, 2021

Greetings from an undisclosed location in my apartment. Welcome to COVID Transmissions.

It has been 501 days since the first documented human case of COVID-19. I’ll be honest, as a huge Star Wars fan, I can’t help but think of Darth Vader’s personal stormtrooper legion, the 501st, any time I see that number. Say what you will about Darth Vader, he had excellent etiquette about wearing a mask in public.

We’re going into another weekend, and I hope you enjoy it. The weather should be gradually getting better, and I encourage everyone to enjoy the outdoors! It’s the best place to be during this pandemic, if you’re leaving home.

Today I’m covering headlines on the duration of vaccine-induced immunity and a new, over-the-counter rapid antigen test—something that could be a real game-changer.

As usual, bolded terms are linked to the running newsletter glossary.

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Now, let’s talk COVID.

Pfizer: vaccine-induced immunity lasts at least 6 months, and vaccination appears effective against B.1.351 variant

Today, Pfizer released data from the first 12,000 patients to reach 6 months of follow-up in their ongoing COVID-19 trial. In this cohort, the vaccine was 91.3% effective based on 927 total cases of COVID-19.

I’m sure if you went back in the archive, you would find a moment where I wondered if vaccine-induced immunity would be durable. This is the first evidence that it is. Relative to the original results, this is such a small decline in efficacy that I seriously doubt it represents a decline at all. Instead, because exposure events are essentially random, I expect this slight drop is something that I predicted when the first results were released: that over time, more people from the vaccine arm who remain susceptible to COVID-19 would encounter the virus. I don’t think the drop from ~95% efficacy to 91.3% represents much other than a process of regression to the true mean efficacy for this vaccine.

Since 91.3% is an unbelievably amazing efficacy, that’s good news.

Also important about this is that the follow-up now far exceeds the portion of time that the CDC is willing to say people recovered from COVID-19 are likely to be protected. The CDC is quite conservative in saying that you can expect protection for at least 3 months from natural infection; it likely lasts much longer, based on available evidence. Still, I think it’s meaningful to see that this particular vaccine obviously remains highly effective for twice that period of time, if not longer.

Another key line in this press release is “side effects were generally consistent with previously reported results.” This means that they saw no “time bomb” safety signals, where 6 months after vaccination people suddenly started sprouting extra limbs (to use a ridiculous example). That’s what I expected—the vaccine contains sequence from the virus, some lipids, and some stabilizing ingredients that are commonly used in personal care products. I wouldn’t expect to see anything 6 months after vaccination that we wouldn’t see 6 months after getting the virus, and in fact would expect much less serious effects than the virus produces in the long term. That’s what we see. Still, you never really know until you have the data. Now we’re getting the data, and everything looks good.

The last piece of this report I want to touch on is that the vaccine was 100% effective in patients living in South Africa. In South Africa, the B.1.351 variant is highly prevalent, and there have been a lot of worries about this variant because it has several apparent antibody-escape mutations. To know that this vaccine remains effective against that variant is very reassuring. Keep in mind, of course, that the “100%” there is probably an overestimate due to small event numbers. I imagine the vaccine is approximately as effective against this particular variant as it is against COVID-19 caused by other virus lineages in general.

Pfizer press release here: https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-confirm-high-efficacy-and-no-serious

FDA authorizes two over-the-counter, at-home rapid antigen tests

Since the beginning of the pandemic I have been hopeful that a rapid antigen test would become available. You may have had a rapid antigen test performed at some point in the past—these are tests that use an immune reaction to detect some particular target. Common rapid antigen tests that people receive include Strep tests and pregnancy tests (against a pregnancy-specific hormone). Generally, if a test involves exposing some bodily fluid to a card and waiting for a few minutes, there’s a good chance that it uses a rapid, antibody-based antigen detection method.

For COVID-19, the nice thing about a rapid antigen test is that it would be likely to detect really active infections. RT-PCR, the basis for most other testing, is very sensitive and returns positives in a lot of situations where a patient might not actually be contagious at all. Rapid antigen tests are less sensitive, but the infections they do pick up are, in my opinion, higher-risk ones. The presence of virus antigens implies the presence of functional virions, which can spread and infect.

Folks like Dr. Michael Mina, the real champion of rapid antigen testing in the US, have advocated that these tests, if made cheap and widely available, would allow a return to basically normal life. Imagine if, using a $1 test, you could test yourself every morning and stay home if you turn up positive, at least until you confirm your diagnosis with a doctor. Imagine if everyone could do that. Even if the test only detected 70% of active infections, that would reduce the population out and spreading COVID-19 substantially. In a lot of places, even stay-at-home orders didn’t reduce the spread to the degree that that might.

The problem is, there haven’t been rapid antigen tests authorized in the US until now. Yesterday, the FDA approved two, as described here: https://www.npr.org/sections/coronavirus-live-updates/2021/04/01/983318237/fda-approves-2-rapid-at-home-covid-tests

We’re not quite looking at $1/test here, though. It’s more like $8-10/test, which is more than the federal minimum wage. That might be a problem to allow individuals to test themselves every day ($300/month is more than rent in some places!), but it could be cheap enough for employers to require them for on-site employees. This directly interests me because I sit on my company’s pandemic planning committee, and I think I’m going to go ahead and recommend that we supply these free of charge, and require them, for people coming into the office and for field force representatives who are doing in-person meetings.

What am I doing to cope with the pandemic? This:

Vaccine follow-up

I wanted to update you all on my experience with the Pfizer vaccine. The pain in my arm almost entirely went away by 24 hours later. However, at that point, an extreme amount of fatigue set in. I was wiped for a couple of hours. Thankfully that was pretty short-lived.

All in all, I’ve had worse vaccine experiences, but this was definitely a little more noticeable than others. I’ll return to this topic when I get dose 2, which is coming up in just under 3 weeks.

Reader Jim Prego had the following comment on his and his family’s vaccine experiences:

Congrats on the vaccine! I brought my mom to the stony brook location, also state-run and it was super-efficient. I was highly impressed by the state, their organization and professionalism. I however, ended up going to a Suffolk-county location to get my shot and it was very fly-by-night. You generally had to guess where to park, how to get to the building from there, staff was writing your info on pieces of scrap paper, little signage or info about things. They also don't give 2nd appointments during your 1st shot! You had to wait til a day before the day you are supposed to get your 2nd shot to get an e-mail with your appointment and for me at least they had me go to a different location, and a different time from my 1st, also seemingly slapped together last minute.
I never realized before the degree disparity in state vs county resources.

My reply:

I'm hearing similar things about state vs city resources. However, I've heard some counties are really doing a great job--I'm told Westchester is working well. I think this is a theme overall around the US and in the world; there is a lot of local variation in vaccine availability and efficiency of distribution systems.

I shared this comment because it highlights how it’s difficult to cover global vaccination in a daily newsletter like this one. Jim lives not too far from me, in Long Island. He had a wildly different vaccination experience than I did, and New York State is doing quite well. Friends of mine in Pennsylvania have reported more difficulties, as have friends in farther-flung locales. Someone who lives in Europe told me yesterday that they’ve considered flying to the US to get vaccinated because of the problems in the country that they’re living in right now.

There’s so much local variation in the logistics that it’s hard to capture the situation holistically, except to say that I hope universal vaccine availability comes soon! We really need vaccination against COVID-19 to be cheap, easy, and available everywhere.

You might have some questions or comments! Send them in. As several folks have figured out, you can also email me if you have a comment that you don’t want to share with the whole group.

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