This preprint, which was just released today, says that while some of the Covid-19 variants evade antibody immunity, they do not evade T-cell immunity. It says that this is true both of T-cell immunity obtained naturally by contracting standard Covid-19, and of T-cell immunity obtained through the Pfizer and Moderna vaccines.

My question is, what degree of protection does T-cell immunity confer against Covid-19? Have there been any studies on how effective it is against preventing severe disease?

  • If you mean alone, probably not, because (1) animal models for Covid, while they do exist, failed to produce severe disease and (2) creating [only] T-cell immunity but not humoral immunity (antibodies) in vivo in humans is basically impossible (I mean in an ethical/safe manner--giving someone vaccinated a challenge with an engineered virus that bypasses their known/assayed antibodies is possible, but for something like Covid it's unethical.) So any studies would have to be long term and/or observational. Commented Mar 8, 2021 at 20:31
  • Aside: with the (political) hoo-hah of Covid allegedly being escaped from a lab (or even bioweapon) experiment, can you imagine how hard it would be to get approval to design a Covid strain that bypasses some known/large set of antibodies... Commented Mar 8, 2021 at 20:39
  • @Fizz Well, do we have the ability to make educated guesses, based on similar viruses for instance? Commented Mar 8, 2021 at 20:41
  • N.B. there is actually one sub-species of hamster (P. roborovskii) that gets a bad form of Covid-19; this was reported in Dec last year though sciencedirect.com/science/article/pii/S2211124720314777 I'm guessing there aren't a lot of studies that use it yet. That paper only has 4 citations in Google Scholar at the moment. Commented Mar 8, 2021 at 23:06


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