It's common for viral infections in general to depress immunity in their aftermath (why bacterial infections are quite common after flu, for example). Though covid may be doing this in different ways and for longer.
There's more and more mention of this about in discussions online between scientists and doctors, though English language newspapers aren't covering it much, albeit some articles present it as one of a set of competing theories. (It is not settled in the wider medical/scientific community.)
Vespertine t1_izpmpp3 wrote
Reply to comment by Jetztinberlin in A Swedish study of over 200,000 people who tested positive for SARS-CoV-2 between March 2020 and July 2021 has found that women, people with asthma and those with previous mental health disorders are more likely to experience long-term effects of COVID-19. by MistWeaver80
It's common for viral infections in general to depress immunity in their aftermath (why bacterial infections are quite common after flu, for example). Though covid may be doing this in different ways and for longer.
There's more and more mention of this about in discussions online between scientists and doctors, though English language newspapers aren't covering it much, albeit some articles present it as one of a set of competing theories. (It is not settled in the wider medical/scientific community.)
2021: https://pubmed.ncbi.nlm.nih.gov/33821250/
https://www.nature.com/articles/s41423-021-00750-4
recent preprints (late 2022):
https://www1.racgp.org.au/newsgp/clinical/even-mild-covid-cases-can-have-lasting-effects-on
https://www.frontiersin.org/articles/10.3389/fimmu.2022.1034159/full
General media articles taking issue with 'immunity debt' or the way the term is being used:
https://www.ft.com/content/0640004d-cc15-481e-90ce-572328305798
https://www.liberation.fr/societe/sante/bronchiolite-et-dette-immunitaire-un-concept-fumeux-qui-ne-tient-pas-la-route-20221209 (article by medical doctor)
https://www.irishtimes.com/health/your-wellness/2022/11/28/has-covid-19-caused-permanent-damage-toour-immune-systems/ (article by medical doctor)
Presenting it as one among various possibilities:
https://www.theguardian.com/commentisfree/2022/dec/06/strep-a-uk-myths-deaths-children (article by academic health scientist)