Invaders v.s. Antibodies: Dawn of Immunity

My wife and I got our first dose of the Pfizer vaccine about a week and a half ago. According to the Phase 3 trial results, enough time has now passed since the first dose for vaccinated people’s incidence of symptomatic COVID-19 to begin diverging from the unvaccinated population.

I don’t feel any different, but if I understand correctly — full disclosure: I may not, so please don’t rely on any of this to make medical decisions — the mRNA payloads in the vaccine have goaded my body’s cells to produce a bunch of Covid-style spike proteins, and those have been knocking around my body long enough that my adaptive immune system has decided to take them seriously as a threat. (My innate immune system is probably always busy killing some damned thing or another. It would be wasteful — and possibly hazardous — to mount a full immune response to every stray protein.) The components of my adaptive immune system have somehow identified the threat and activated armies of B and T antibody cells that really, really hate those spike proteins specifically.

I don’t know how quickly the spikes will be eliminated from my body, but a slowly dwindling army of immune cells will remain in my body for weeks to come. If any more of the spiky-protein invaders show up, the circulating antibody cells are going to pounce immediately and destroy those proteins and, importantly, any cells in my body that begin to produce more of those proteins.

It will be a race between infected cells that are producing spiky viral particles and antibody cells that are killing them off as fast as possible. Unlike the first time those spiky proteins appeared, this time the attack will be instantaneous, and it will either be immediately victorious, or it will likely slow down replication enough that my immune system can rally and win the fight. In the former case, and some variations of the latter, I’ll never even notice something was happening.

After a few weeks, if there is no return of the spiky invaders, almost all of the SARS-CoV-2-specific antibodies will have broken down and stopped circulating.

Almost.

A few of the antibody cells will linger, certainly for months, possibly for years, perhaps for decades. If the spiky invaders return, this time there will be no question of whether they should be taken seriously. The lingering immune system cells will remember, and they will begin rebuilding the antibody army very quickly.

How strongly these memory cells respond to a renewed invasion depends, in part, on whether the spiky invaders have shown signs of being a persistent threat…

(To be continued.)