COVID Transmissions for 3-11-2021

If you have COVID-19 antibodies already, how does that affect vaccination?

Good morning and welcome to COVID Transmissions.

It has been 479 days since the first documented human case of COVID-19. In 479 CE, Ambrosius Aurelianus became King of the Britons. In real life, he fought the expanding Saxon colonization. In myth, he became interwoven with Arthurian legend, finding his way into various stories as Arthur’s uncle. Memory can be a strange thing.

Immune memory can also be interesting, and we’ll talk about that today. Also, a sports story. I’m surprised myself!

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

Keep COVID Transmissions growing by sharing it! Share the newsletter, not the virus. I love talking about science and explaining important concepts in human health, but I rely on all of you to grow the audience for this, which you can do by using this button here:

Now, let’s talk COVID.

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If you’ve had COVID-19 before, you might have a stronger immune response to COVID-19 vaccines

We’ve talked about this before, but some new data are now available. The research question at hand is whether people who have already have COVID-19 have stronger responses to first (and second) doses of vaccines against COVID-19. This could be important for vaccine supply—what if these people don’t need to get the second dose at all?

While I’m afraid I can’t quite answer that question, there are some new data in the New England Journal of Medicine that compare the immune response to mRNA vaccines (Pfizer and Moderna, but mostly Pfizer) in patients with detectable antibodies to SARS-CoV-2 vs those who do not have detectable antibodies. You can read the full letter here: https://www.nejm.org/doi/full/10.1056/NEJMc2101667

Of course, I’m still going to summarize for you as well. Here are the key antibody data from the letter:

Image is a graph showing antibody levels in patients who were negative for SARS-CoV-2 antibodies (“seronegative,” blue) compared with those who were positive before vaccination (seropositive, gold). It shows levels of anti-SARS-CoV-2 antibodies from before the first dose of vaccine, and then over subsequent periods of four days, and then again after the second dose. After the first dose, there is a relatively quick increase in antibody levels among patients who are seropositive, and the levels reach a higher peak than in the seronegative patients. By the time of the second dose, antibody levels are comparable, but the seropositive patients appear slightly higher. Image from NEJM.

So what we see here is a rapid induction of antibodies in the patients who were already positive for anti-SARS-CoV-2 antibodies. What’s more, that rapid induction reaches a higher level than in the patients who were negative for antibodies before their first dose. After the second dose, the groups look pretty close to one another, but the previously-positive patients are still a little bit higher. So all in all, it looks like previous exposure to SARS-CoV-2 offers a bit of a boost in antibody levels in vaccinated people.

One thing that’s interesting here is that being counted as “seropositive” required only one historical sample showing antibody-positivity, so even before the first dose there are some patients in that group whose antibodies have fallen to an undetectable level. Earlier in the pandemic, much hay was made over people’s antibodies falling below the limit of detection quickly. It was said then that this is evidence of immune waning. Well, here we can see that there is still an immune memory response. That is good news.

The authors also looked at the rates of safety events in each type of patient. The seropositive patients appeared to meaningfully higher rates of systemic reactions, which sort of makes sense to me—they have developed a systemic immune response in the past, and the vaccine activates that. I don’t want to cause a panic, so let me note that these don’t appear to have been serious reactions. What I think we’re seeing here is validation of the existing immune response, not a major cause for concern.

Anyway, based on this, it seems that indeed patients who have ever tested positive for SARS-CoV-2 antibodies have a stronger immune response to the mRNA vaccines. This could have big implications, particularly if it turns out that one dose is enough for people who have already had COVID-19. We will need more work to know that for sure.

Major league sports as a source of COVID-19 data

The Wall Street Journal has an interesting article about how, because of regular testing and the availability of resources to study COVID-19 in these settings, major league sports teams became an important source of data on the pandemic. Have a look here: https://www.wsj.com/articles/covid-testing-sports-nba-nfl-11615352090

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

Bike riding under spooky clouds

I biked home today after a gym session, but before I hopped on my bike, I saw this near the Javitz Center:

Image shows a sky filled with a cover of thin clouds that have a continuous roil to them, giving the effect of almost a sheet of crepe paper in the sky.

I don’t know what to call this cloud effect, and I’ve never seen anything like it before. These were very thin clouds, but with such defined texture. I don’t know what to call it, but the scene was beautiful. Anybody meteorologically-inclined care to fill me in?

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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.

Join the conversation, and what you say will impact what I talk about in the next issue.

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Part of science is identifying and correcting errors. If you find a mistake, please tell me about it.

Though I can’t correct the emailed version after it has been sent, I do update the online post of the newsletter every time a mistake is brought to my attention.

No corrections since last issue.

See you all next time.

Always,

JS