I don't think your conclusion from the article is correct or valid. I think you are over-interpreting what the article says. Note, however, that I am not claiming any expertise, or even any significant level of competency, in this or any associated field. (Neither am I claiming that I fully understand everything that is written in the article!)Originally Posted by Witton Park
My purpose in making this post is not to make any claims as to what the conclusions from the article should be, but rather simply to make the case that (based on my understanding) the conclusion that "up to 81% have a had some T cell response to COVID, which would mean lots of people have immunity" is not a correct nor valid conclusion to be made from the article. Certainly it is not, as far as I can see, a claim made anywhere in the article itself.
Here is a quotation from the second paragraph of the Discussion section:
"Notably, we detected SARS-CoV-2 cross-reactive T cells in 81% of unexposed individuals. To determine if these T-cells indeed mediate heterologous immunity and whether this explains the relatively small proportion of severely ill or, even in general, infected patients during this pandemic32,33, a dedicated study using e.g. a matched case control, or retrospective cohort design applying our cross-reactive SARS-CoV-2 T-cell epitopes would be required."
My understanding is that this does not mean that "81% have a had some T cell response to COVID". My understanding is that, on the contrary, these individuals have had NO exposure to SARS-CoV-2 / Covid-19. That's what the "cross-reactive" and "unexposed" parts of the quotation mean. My understanding is that "cross-reactive" means that these T cells have come about through exposure to something other other than SARS-Cov-2 (i.e., they are not SARS-CoV-2-specific T-cells). The 81% refers to the 185 individuals in the study who had NOT been exposed to SARS-CoV-2. Basically, my understanding is that what they are saying is that, of the 185 indiviiduals in the study who had not been exposed to SARS-Cov-2, 81% of them had been exposed at some time to something else which created T cells which are highly relevant and of interest in terms of the body's response to SARS-Cov-2 infection but which are not (obviously, because there has been no SARS-Cov-2 exposure) SARS-CoV-2-specific.
Neither does it mean that "lots of people have immunity" to SARS-CoV-2. It's possible that this is true, but the paper certainly does not say that this is the case. Rather, it specifically says that a dedicated study would be required to understand what the consequences of their findings are in relation to possible immunity from SARS-Cov-2 (see the quotation, above).
The study involved 180 individuals who had been exposed to SARS-Cov-2 and 185 who had not been so exposed. This seems a small sample to me if the objective of the study was to provide wide-ranging conclusions relevant to levels of infection and immunity. However, this was not the objective of the study. Rather, the objective was simply (!) to identify and characterise "SARS-CoV-2-specific and cross-reactive HLA class I and HLA-DR T-cell epitopes". (And, no, I don't claim to fully understand exactly what that means!)
Note, again, that all the above is based on my understanding. I would be happy to be corrected on any of my interpretations of what the article is saying (provided, of course, that sensible supporting evidence is provided).
I would suggest that it's also worth noting the comment at the top of the web page:
"This is a preprint. Preprints are preliminary reports that have not undergone peer review. They should not be considered conclusive, used to inform clinical practice, or referenced by the media as validated information."
