science note no one is going to care about: I think a lot of the fear about rapidly fading immunity to the virus is based on SARS/MERS evidence that may be misleading. Serum antibodies are easy to measure but don’t seem central to real immunity.
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what really counts are memory T cells, especially tissue-resident ones in the airway itself. Harder to measure but some evidence suggests they are indeed long-lasting.
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however, there is at least one unpleasant study in monkeys suggesting that exposure to SARS 1.0 does produce enough immunity to wipe out the virus within 5 days upon reinfection...but lung damage still occurs
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I have an educated guess about what’s happening here: in a natural first-time infection, most of the viral clearance is done by CD8+ T cells. Antibodies appear late, after the party is over, and don’t do very much.
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However, upon reinfection, memory B cells and Tfh cells are ready to go from early on. Antibodies are produced much earlier. But this is actually pathogenic. Why? Probably something to do with IgG antibodies getting into the lungs and activating macrophages via FcR
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this (plus a lot of other evidence that these margins are too narrow to contain) is a quite bad omen for most vaccine strategies, which historically have had far more luck eliciting antibody responses as opposed to T-cell responses
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it strikes me as quite plausible that, as with RSV, many vaccine candidates for this will be worse than nothing
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this model may also shed light on what’s happening in the ARDS phase of the disease. Probably a lot of things, but one of them might be: the worse a job the innate cells and T cells do of defeating the infection early on, the more time it gives B cells to pump out antibodies
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these antibodies, triggering various effector mechanisms in the lungs, induce a new round of inflammation and damage, analogous to transfusion-related acute lung injury
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abstract of a new preprint out today looks supportive of this basic concept: "stronger antibody response was associated with delayed viral clearance and disease severity." That's not really how it's supposed to work! https://www.medrxiv.org/content/10.1101/2020.03.24.20042382v1 …pic.twitter.com/XPkXoRmbHM
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yech, I saw that, very weird.
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