COVID Transmissions for 1-20-2021
Past infection can mean protection
Good morning and welcome to COVID Transmissions.
It has been 429 days since the first documented human case of COVID-19.
Today I have a story that I have been quite eager to share with you. There is now evidence that a past recovery from COVID-19 may imply you are protected from the disease in the future—but this comes with a lot of caveats, so please read on. It’s a short newsletter today but that’s big news.
As usual, bolded terms are linked to the running newsletter glossary.
Keep the newsletter growing by sharing it! 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:
Now, let’s talk COVID.
US surpasses 400,000 deaths
We’ll start with the bad news: the US passed 400,000 official COVID-19 deaths today. A grim milestone. Stay safe.
Recovery from COVID-19 appears to confer protection from future COVID-19
For months, I have been forced to tell you and anyone who asks that there is no clear evidence that being ill with COVID-19 results in protection from COVID-19. This was difficult to study, because we are talking about a new and deadly illness, and experiments cannot be directly conducted to see if those who have recovered are still vulnerable to illness.
I am happy to report some new information that changes all of that. A study from Public Health England indicates that the protection conferred by recovery from COVID-19 is 83% effective at preventing future cases of COVID-19. This is similar to the 60-95% protection offered by various vaccines on the market. To me this is extremely exciting news. You can read about it in this story from The Guardian here: https://www.theguardian.com/society/2021/jan/14/recovering-from-covid-gives-similar-level-of-protection-to-vaccine
This study had 21,000 patients (all of them healthcare workers), which is a nice sample size. But we have to keep in mind that 83% protection is not 100%, and this study also does not give us a clear sense of the duration of that protection. The followup lasted only from June to November, so we cannot say much beyond that time.
Also, the methodology narrows the potentially protected population. In the study, patients were checked for the presence of SARS-CoV-2 antibodies as a sign of past infection. I think many of you can report personally that past SARS-CoV-2 infection does not always imply a future positive antibody test. We also know that there are in fact cases of reinfection with SARS-CoV-2, both with and without symptomatic disease.
So we need to apply the restriction that this protection is only applicable in the patient group that had detectable antibodies. Even then, the protection was only 83%.
This tells me that while someone who has recovered from COVID-19 can expect to have some protection, even if they remain antibody-positive, they would do well to continue to be careful and observe various disease control restrictions. Masks, minimizing trips out, and maintaining distance from others still apply to people in this situation. However, people in this category may rest slightly easier knowing that if these measures fail for them, they may still be protected from disease.
You can read the full study—a preprint—here: https://www.medrxiv.org/content/10.1101/2021.01.13.21249642v1
What am I doing to cope with the pandemic? This:
Watching the Inauguration
Today, the US will have a new President. I’m going to watch the ceremony and speech in between working. We’ll see what he has to say. There’s a lot of work to do.
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