Wikipedia:Reference desk/Archives/Science/2022 July 11

= July 11 =

Long Covid and T cells
Is there any reliable evidence that Long COVID depletes/damages T cells? I have heard this assertion repeatedly, and seen some anecdotal evidence to suggest it might be true for some people. I don't know if there is any reliable peer reviewed evidence to support this claim, but the wiki article on Long Covid makes no metion of T cells anywhere.Uhooep (talk) 09:16, 11 July 2022 (UTC)
 * First of all, it seems fairly well-established that the acute phase of covid-19 depletes T cells. (I could not tell from your post whether that fact is obvious or not to you.) See for instance T cell responses in patients with covid-19 by Chen&Werry, published in Nature Reviews Immunology in July 2020 (= forever ago in terms of covid-related-research), which says One prominent feature of SARS-CoV-2 infection is lymphopenia (i.e. depletion of lymphocyte cells).
 * But the question is about long covid, and for that, the answer seems to be a resounding "maybe". From the highly scientific method of typing "long covid" t cell in Google Scholar and picking out the articles with the most cites, I found:


 * 1), a review, puts out some evidence (§2.6) that lymphopenia causes long covid (rather than the other way around): patients with an underlying condition that causes lymphopenia will not recover well from covid. However, the author seems decided to pin the blame on Toxoplasma gondii without much consideration of other alternatives, so I have a feeling the paper might be a bit fringe-y (as in "pushing a minority opinion" fringe, not "earth is flat" fringe; it was still published in a good journal).
 * 2), a primary study, describes a correlation (long covid patients have lymphopenia) but does not explain causation and invites further research into that area (which is boilerplate but I assume the authors have done their bibliography and know that there is a gap there)
 * Tigraan Click here for my talk page ("private" contact) 13:31, 11 July 2022 (UTC)