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I'm *really* not an immunology expert at all, but quick thread here on post-SARS immunity. It's been somewhat taken for granted (including by me) that SARS had induced durable t-cell responses in survivors. But upon closer inspection, that doesn't seem to be the whole story.
The study everyone quotes is this one, but it assessed a grand total of *THREE* survivors of SARS, and found that they still demonstrated t-cell responses 9-11 years after they contracted the disease. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7115611/
Tang and co found that 60% of their sample of 23 patients had induced a memory t-cell response 6 years later. And also that "Patients with more severe clinical manifestations seemed to present a higher level of Ag-specific memory T cell response" https://www.jimmunol.org/content/186/12/7264.long
Fan and co found that 70% of their sample of 21 patients had induced t-cell response 4 years later. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796960/
In a study with a larger sample size than either of the previous two (n=128), Li and co found that only 50% of them had a demonstrated t-cell response *one* year post-infection https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2683413/
Anyway, if we take SARS as representative of what will happen with Covid (yes, this is a HUGE assumption that is likely untrue), the probability and duration of immunity are nowhere close to perfect, and any "herd immunity" obtained purely by prior infection will be short lived.
It's possible the immunity to Covid is better than that of SARS, or, you know, worse.
I also have no idea what this means for the duration of immunity attained from vaccination.
I also have no idea what this means for the duration of immunity attained from vaccination.
I hope I'm wrong & that there's good reason to expect/hope that the immunity from infection by sars-cov-2 will be awesome. Others can better speak to that given their expertise (i.e., @VirusesImmunity @profshanecrotty @halvorz @stgoldst @LucreSnooker @__ice9 among many others)
Interesting thread, and more optimistic than the implied data from yesterday https://twitter.com/deeptabhattacha/status/1298376137639260165?s=20
Also found this *excellent* and super-informative interview with @profshanecrotty on the "This Week in Virology" podcast (h/t @LucreSnooker) https://twitter.com/profvrr/status/1299000383021256705?s=20
