Mucosal Immunity


“Mucosal Immunity” was a term that I was unfamiliar with until just recently. I know what the words mean, but was not attuned as to how ‘mucosal immunity,’ was relevant to Covid infections, reinfections, and vaccinations.

In a similar vein the recent data out of Israel was a bit perplexing until I decided to try to apply a dose of common sense, and this in combination with my newfound knowledge concerning ‘mucosal immunity’ proved to be useful.

To recap, in Israel the delta variant has caused a new spike in Covid infections. 40% of these new infections were in individuals who had been previously vaccinated, whereas less than 1% (72/7400) were in individuals who had had a prior documented Covid infection. The obvious implication from these numbers is that a prior infection with Covid is markedly more protective than vaccination in terms of contracting a reinfection.

The following is from a recent op-ed in the WSJ by Dr. Michael Segal:

“‘Mucosal immunity’ provides the first line of defense by protecting the nose and mouth, and by doing so also reduces spread to others. The mucous membranes secrete a particular form of antibodies of the Immunoglobulin A type, or IgA.

In contrast, ‘Internal immunity’ protects the inside of the body, including the lungs. This occurs by release of antibodies of the Immunoglobulin G type, or IgG, into the blood and production of T-cells. Vaccines injected into our muscles are highly effective at stimulating internal immunity. This largely protects vaccinated people from being overwhelmed by the coronavirus.”

Dr. Segal continues:

But vaccines injected into our muscles—including all the approved inoculations against Covid—are largely ineffective at stimulating the secretion of IgA into our noses that occurs after actual infection with a virus. As a result, vaccinated people can contract a Covid-19 infection confined to the mucous membranes. They may get the sniffles but can spread the virus to others even if they are asymptomatic.”

The other finding out of Israel is that the effectiveness of the Pfizer vaccine is waning over time, and thus Israel is using boosters to increase the protection afforded by vaccines. Similarly, boosters are now being advised for some individuals, and it will only be a matter of time before all vaccinated individuals will be advised to get a booster. And in the future will these boosters also lose their effectiveness over time requiring boosters for the original booster? Etc, ad infinitum.

So here’s my question:

If the effectiveness of vaccines is waning over time, and the protection from reinfection is very very high among those with a documented Covid infection, does it not make sense to allow those with a minuscule risk from Covid to actually get the infection? Here I am specifically referring to grade school children (who are not eligible for a vaccine), and high school students whose risk from Covid is quite low, albeit not zero. In fact I would extend this to college students. If masks, etc. actually work, would it be better to not impose mask mandates on these groups?

To summarize, I sent the following letter to the editor to the Wall Street Journal:

“If, as was stated in Dr. Segal’s op-Ed on 8/16, lasting mucosal (IgA) immunity is only achievable through an actual Covid infection, why are continued mask wearing and social distancing being advised for young children? Since young children tolerate Covid quite well, why wouldn’t logic dictate that they not be protected with masks, etc. in schools, thus allowing them to develop lasting IgA mucosal immunity on their own?”

8/23/21

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