Sunday, December 13, 2020

The Expert Skinny on COVID Vaccine

Here's a free-wheeling vaccine discussion with the Slog's longtime technical advisor, who prefers not to attach his name, because, I suspect, he was writing off the cuff (as a scientist, he feels obliged to be more rigorous publicly than in informal conversations with friends).

His words weren't chosen with weighty care, and his conclusions were cheekily stated, so this might not pass muster for publication by a scientific journal. But in terms of useful savvy - a well-informed expert laying out what's really going on, in (more or less) plain language - you couldn't ask for better. It's a great read.

Me: Would you chance an airline flight post-vaccination? Or does 90% effectiveness plus undetermined length of immunity leave too much uncertainty?

Technical Advisor: Of course. Apart from the fact that I hate flying, of course.

90% efficiency is the lowball number for the leading candidates. It means that some people will still get infected, but so far none of the tens of thousands in the trials developed a serious (ICU-grade) disease. In fact one of the vaccines (don't remember which) shows so far a 100% efficiency against even moderate infection. There will be a few cases that slip through, eventually, but the probability will be far lower than slipping in the bathtub.

Length of immunity looks good so far, and will likely get better with later versions. In any case, booster shots can always be given regularly, and they use lower doses, thus minimizing side effects even further. If the virus continues to circulate, boosters may not even be necessary, as asymptomatic re-infection would self-boost the system.

Me: How does noncompliance affect this? I know we expect a certain amount, and there’s slack (especially given the surprisingly high effectiveness). But what if compliance is surprisingly low?

Technical Advisor: What kind of noncompliance, though?

Not getting the vaccine is, well, not getting the vaccine. Lots of people choose to smoke, and they die.

Not getting the second shot could be deleterious for the two US ones (so they claim, but perhaps they are just covering their asses), but it appears that the Oxford one may be able to provide most of the immunity with just the first dose (although perhaps not as robust, so more -- albeit less severe -- infections would be expected.) It's all conjectural at this point, naturally, only time will tell.

Not getting later boosters (if recommended) may vary enormously depending on the type of vaccine; long-term immunity has nothing to do with antibody persistence (which is easy to measure), it's all about memory cells (and that's rather hard to measure since it requires lengthy cell cultures, at best).

A memory cells is like a stem cell specific for one antibody; if it encounters the antigen (bug or vaccine) for which it carries the antibody instruction, it is stimulated to start dividing and differentiating into all the different types of antibody-producing cells (IgG, IgM, IgA mostly) as well as some ancillary ones, all directed against that particular antigen. In Theory, as long as there is just one memory cell left over from the vaccination, challenge with the antigen will produce a rapid response.

Boosters are more often effective than re-infection, because the adjuvants cause a non-specific stimulation of the immune system, so the vaccine is more effective than the virus (alive or dead). Still, re-tickling once in a while the memory cells by the virus will wake them up and revive that cell line.

The response speed that the memory cells afford is important, because it shortens the non-specific (interferon) immunity, which can degenerate into a massive cytokin storm, which appears to be a major morbidity factor. The faster antibodies are produced, the faster the cytokin response shuts down. Let go of the chainsaw once you've found your nail clipper.

Me: I’ll try to clarify my question. If a large segment of population doesn’t vaccinate at all, how would that affect the situation? Is vaccine-immunized herd immunity in jeopardy if compliance is even more disappointing than expected by authorities?

Technical Advisor: Oh, that. Vaccinated people are protected, unvaccinated ones take their chances. In the US, people are allowed to make their own decisions and take their lumps. We still get cases of polio, measles, etc; their choices, their lumps. And if the children die, jail the parents. (This is not specifically an American problem, BTW, over 50% of the French say they will refuse the vaccine, and nearly as many of the Swedes.) Once the vaccine is here, it's back to a matter of choice; you choose protection or you don't. If you don't, it's like smoking or not using your seat belt.

Herd immunity is a lagniappe once vaccination is available; I firmly believe that it cannot and should not be made into a major player the way it would be without a vaccine. Encourage people to vaccinate, muzzle RFK Jr and Gwynneth Paltrow, by all means, but as long as YOU get your vaccine, you're OK, and let the others deal with their choices, however stupid they are. Even Socialstyrelsen, which delights in telling Swedes how many slices of bread they must eat, is shying away from compulsory vaccination.

Note that Technical Advisor knows this because he, naturally, follows the Swedish press. In Swedish. When not translating novels into Esperanto.

Me: Going back to fundamentals, what’s the difference between Covid vaccine and polio, measles, etc, where the unvaccinated DO imperil the rest of us?

Technical Advisor: No difference. The unvaccinated polio or measles carriers do not imperil the vaccinated, they only imperil the other unvaccinated. Once you're vaccinated (and get boosters wherever appropriate) you are taken out of the pool of potential victims. It's them but not us.

Depending on the exact circumstances, there may be a small amount of (usually benign) leakage, since immunity persistence is not a precisely determined effect, but by and large, that's it. Measles epidemics happen among the unvaccinated only, which does include a lot of small children, but this virus is fortunately not targeting the very young, so that's out of the way.

Me: Huh. So the non-civic-mindedness angle on anti-Vaxxers is misplaced. I’d bet 90% believe they’re endangering the public. 

Though on second thought, I suppose it’s right because they’re essentially creating safe harbors for pathogens that otherwise might be eliminated.

Technical Advisor:
I’d bet 90% believe they’re endangering the public.
They are endangering the unvaccinated public, which does include a small number who aren't unvaccinated by choice but by necessity: people with severe immune deficiencies or on immunosuppressants in particular.

However in this particular case the two traditional major classes of undervaccinations are not relevant: the elderly, because it seems that the vaccines do work on even the very old (Queen Elizabeth and Prince Philip are scheduled to be among the first to set the example in Britain), and the babies are anyway not a target for the virus.

The only really problematic cohort is the transplant recipients, who already know they must be extra careful in any case, because any infection will be more severe for them no matter what. Even then, it's quite possible that some vaccines may work on them, depending on their profile of action (and here I'm totally in the dark, the intricacies of immune response are way beyond my ken).
They’re essentially creating safe harbors for pathogens that otherwise might be eliminated. 
Yes, but only for those pathogens without non-human hosts. Smallpox could be wiped out, polio should be soon, but influenza and corona viruses have huge wild animal reservoir hosts, so they will never be eliminated. 

Great short explanation by a doctor of how the vaccine works

Same doctor explains why the vaccine will work even with mutated version of COVID virus

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