WHY YOU TRANSMIT

Twenty-nine months into this pandemic I'm still running into folks who think that being immunized means they're immune to infection and its consequences and, more impactfully, also unable to transmit the virus. None of this is so and, least of all, the transmission piece. Why is that? (And why does the lack of public education and awareness make me crazy?)

PAST

I couldn’t have been more interested in biology in high school. At the beginning of my grade twelve bio class a discussion around vaccines and the immune system came up. I asked why the immune system, trained by prior infection or vaccination, forgets some viruses quickly while others are remembered seemingly forever. The teacher gave some embarrassing bullshit answer that didn’t even make sense to her; but she stuck with it and so I stopped paying attention, like, for the rest of the semester. I was still interested in biology, as I am today, this teacher just didn’t have the minimal requisite characteristic of a teacher (or adult): that of being able to admit when you don’t know something or, after the fact, acknowledging you were wrong. (If you’re interested in the answer to my question please watch this fabulous three-part series from the British Society for Immunology and Cloud Chamber Studios UK Science Animation: Emergency Response, How Do Cells Remember?, and Why Do Immune Systems Forget?)

Relevant tangent: I sat at the back of the class, near my friend Navida. By mid-semester I would spend much of the lecture with my head nested in my crossed arms on my desk. I could not have been less disruptive while still being present. The teacher took this as an insult, which was not the intention but also felt appropriate. Tired of this happening, she eventually threw a stapler at me, taking a chunk out of the cupboard door just above my head. I remember that stapler well. It was a grey, textured steel industrial Bostitch (model B5B, “The Masterpiece of Staplers”.) Thing probably weighed half a standard brick and, despite its shape, flew like a hatchet. Regrettably, she missed my face. She screamed, as only a teacher nearing retirement can, and told me I was falling asleep due to a lack of oxygen and that I needed to stand beside my desk for the whole class. Kids, these were the exemplary senior teachers (at the height of their experience and income bracket) dominating the profession in the ‘90s – prior to ubiquitous on-person cameras. Good times.

PRESENT

It was probably this experience in biology class, at least in part, that has me so intolerant of the appalling science communication during our pandemic. As no health official would (could?) explain to the public why our COVID vaccine is incapable of curtailing transmission, just as in biology class, I had to go find out for myself.

Like all of biology, it’s complicated. The simplistic version for non-biologists like myself is that those vaccines that stop transmission are typically combating viruses who replicate internally in the blood, lymph, or deep in the lungs before they begin transmitting. So, as with measles, say, if the vaccine can eliminate internal replication then, obviously, the transmission that would otherwise follow cannot occur.

To contrast, upper respiratory viruses (like what we have with SARS, SARS2, influenza, and others) often don’t require this same kind of internal replication. Mouth, nose, and throat infections are special beasts. And immune response to pathogens in these locations are different than elsewhere, too. But, basically, viruses specializing in the upper respiratory ecosystem are happy to alight on any friendly moist surface and do the business of replicating and shedding from there. So, any vaccine blocking internal infection and replication – and, as a result, preventing disease in the host – may, obviously, do little in preventing transmission of the virus.

It’s all more nuanced and messy than this. Virus replication and immunity are super interesting and wonderfully complex. But for most of us I think the above helps make sense of the basic science and the situation we find ourselves in.

FUTURE

The other issue with our current vaccines is that we now know multiple infections may yield potentially catastrophic health outcomes, regardless of your vaccine status. A large review is about to land in the US, one that looked at the national health care databases of the Department of Veterans Affairs. (Look for it this summer in the journal Nature Portfolio, by Al-Aly, Bowe, and Xie,) We're told that data from more than five million vets shows, whether unvaccinated or having taken a fourth dose, repeated infections compound and result in a real risks of all-cause mortality, hospitalization, and adverse health outcomes at the height of infection and thereafter. Those impacts are far from trivial, covering a wide spectrum from fatigue to diabetes to cardiovascular, kidney, and gastrointestinal disorders, coagulation and hematologic disorders, musculoskeletal disorders to neurologic disorders. You do not want to get infected. And if you do, you absolutely do not want to be reinfected.

In this way, our vaccines have been oversold and the science behind them and this particular virus poorly understood and also not explained. Your shot may prevent you from dying from SARS-CoV-2 but not from outcomes I would consider worse, nor from gifting the virus to everyone you know without even knowing you were infectious.