COVID Transmissions for 7-9-2021
Vaccines: better than natural immunity? In need of a boost?
Greetings from an undisclosed location in my apartment. Welcome to COVID Transmissions.
It has been 600 days since the first documented human case of COVID-19. 600 is a Harshad number in base 10 (as is any multiple of 100, actually); a Harshad number in a particular base is a number that is divisible by the sum of its digits in that base. 600 is divisible by 6 + 0 + 0 = 6.
If that seems somewhat trivial, let’s move on to something that’s far from trivial—understanding the particulars of immunity generated by vaccination against COVID-19. Today we’ll discuss how it compares with natural infection, and also whether a third booster dose may be required for Pfizer’s vaccine.
Have a great weekend!
Bolded terms are linked to the running newsletter glossary.
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Now, let’s talk COVID.
The value of natural immunity
I’ve heard more and more people—one noted example shared with me by a reader recently—claiming that they would prefer to become “naturally” immune to COVID-19, or claiming that their natural immunity from a previous COVID-19 case means that they do not need to become vaccinated.
I’d like to explore the meaning of natural immunity to COVID-19 today, and also share some recent study results that speak to the comparison between immunity following recovery from disease vs immunity gained by vaccination. I don’t love the term “natural immunity,” for what it’s worth. Vaccine-induced immunity is also a natural response. There are a lot of people out there who believe, despite the existence of natural disasters, that if you put the word “natural” into a phrase it means that the thing being described is better. This is why you see “natural” used all over food advertising. Except, natural isn’t always better, as we’ll see. Let’s do some comparative points:
We do know that infection with SARS-CoV-2 produces many long-term effects in people. Immunity happens to be one of the most widespread, but other effects include long-term neurological and physical deficits, increased risk of all-cause mortality, and other issues. The vaccines, incidentally, do not have these risks, and also produce widespread immunity.
Immunity produced by infection with SARS-CoV-2 lasts for at least 6 months, and it is not clear how long it may last in most people; it is possible that it is relatively long-lasting
There is conflicting evidence as to whether immunity resulting from infectious is as protective as immunity from vaccination, however some molecular results have shown that:
Antibody levels are higher in vaccinated people than in people who got immunity from infection: https://www.contagionlive.com/view/immune-response-from-mrna-covid-19-vaccines-is-more-robust-than-natural-infection
Antibodies generated by vaccination are more likely to maintain effectiveness against new variants than antibodies resulting from infection: https://www.nature.com/articles/s41586-021-03777-9 and https://directorsblog.nih.gov/2021/06/22/how-immunity-generated-from-covid-19-vaccines-differs-from-an-infection/
Vaccination against COVID-19 is, without a doubt, superior to infection for the purposes of protection against COVID-19. Infection with SARS-CoV-2 does produce immunity, and I would call it “the next best thing,” except it doesn’t actually constitute protection from COVID-19. If you had COVID-19, you weren’t protected. You might be protected from future disease, but the original disease still happened to you. So while there is protection there, and it is definitely better than nothing, I certainly believe there is a better option—vaccination.
You might think it unusual that a vaccine would produce better immunity than the infection itself, but as it turns out, there are many examples. Tetanus, for example, offers almost no protection from future disease if you happen to survive infection, but vaccination can produce years of immunity. Varicella zoster, the virus that causes chicken pox, yields effective immunity against chicken pox but incomplete immunity against the future disease shingles, which is quite similar to chicken pox except that it causes extreme pain, something that chicken pox doesn’t do. The vaccine against chicken pox also offers protection against shingles, and thus is superior to immunity produced by infection. The HPV vaccine is another example, producing more robust immunity to the virus than infection yields.
So really, we see that it’s not that strange to have a vaccine work better than infection in terms of the quality of protection.
Particularly with variants on the rise—which evolved to escape “natural” immunity—I think it’s more important than ever to be vaccinated. In case I hadn’t made that clear in this newsletter yet.
Pfizer expects to require booster dose
I still don’t particularly understand what motivates these claims, but Pfizer has announced that they will be seeking authorization for a third dose of their vaccine on the basis of apparent “waning” immunity in vaccine recipients. Details here: https://www.cnn.com/2021/07/08/health/pfizer-waning-immunity-bn/index.html
They say that this has been observed in real-world data that indicate vaccine efficacy begins to wane after six months, but the vaccine that they produce has not been in widespread use anywhere for six months at this point. They cite the recent Israeli study, but that study did not allege waning of immunity. The Israeli results were preliminary and the suggestion was that efficacy had dropped due to the spread of the B.1.617.2 (“Delta”) variant. See the last issue of this newsletter, from Wednesday, for my thoughts on that.
Pfizer’s statement implies that they have access to unpublished data that indicate a waning of immunity with their vaccine. That’s possible, but if it’s the case, it’s time for them to make those data publicly available. Particularly because the vaccine is a product that they sell in order to make a profit, it is vitally important that they make it clear these claims of waning immunity are driven by science and not by a profit motive exclusively.
The Israeli data are concerning, but they do not suggest “waning” immunity to me of any kind. Boosting with an identical third dose does not seem to be the solution to me—although there is some discussion in the article that Pfizer will seek approval for a third dose with a modified vaccine candidate. If that is better at protecting people from variants, then perhaps that would be a good thing. But it does not seem to me that that is a consideration based on waning of immunity. That is a consideration based on evolution of virus.
That isn’t merely a semantic consideration. It is one that impacts the risk-benefit calculation of doing a third dose. If this third dose is just to prevent mild disease from variants, and people are still generally well-protected against serious outcomes, is there really a justification for an Emergency Use Authorization? Or should that third dose go through the full and typical FDA licensing process, like all other vaccines?
These are questions I might not have if Pfizer started from the data and then made their claims, but instead they’ve made claims and told us we should wait for the data. That breeds speculation and confusion, and I don’t like it.
What am I doing to cope with the pandemic? This:
Mentoring
I participate in a program for PhD students that connects them with a mentor who followed a nonacademic career path, and yesterday I had my latest monthly meeting with my mentee. I find the experience really rewarding. A PhD is a very difficult time in a person’s life, and it can seem like there is no end or path forward at times. I am glad to be able to offer something of a lifeline to a student who is walking that path.
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No corrections since last issue.
See you all next time. And don’t forget to share the newsletter if you liked it.
Always,
JS