Thread by @Laurie_Garrett

The @HumanVaccineProject lab mtg is today is Shane Crotty from La Jolla Institute is speaking on T cell immunity for COVID. 100% of survivors make CD4 resps., 70% CD8 against broad viral antigens. And never-infected make CD4 reaps based on Common Cold histories.

Here's my take on this:
- the immune response to #COVID19 involves both antibodies & the T cellular arm of the system;
- blood samples from pre-COVID 2015 show high levels of reacting T cells (CD4 & CD8): Why?
- it's likely T-cell reactions to common cold viruses, not COVID
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Are the high reactions anti-common cold good news or bad for #COVID19 vaccines & long term immunity for survivors? Well, it's clear an effective #vaccine will need to trigger BOTH antibody & T cell resps.
BUT common colds circulate all the time, and despite having had..
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..a cold one year, most of us keep catching colds throughout life.
So #coronavirus immune responses may not be robust, or long lasting.
This makes everything about #SARCoV2 vaccine R&D way more complicated.
Most vaccines simply aim to conjure IgG antibodies, & that works.
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Another finding is that IgA antibodies seem to be crucial to fighting #COVID19 which is unusual & mysterious. An effective vax will need to trigger IgA.
This combination of issues -- T cell response, cross reaction w/common colds, possibly short duration of protection..
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...& the mysterious need for what may be IgA antibodies working in concert w/IgG is why #TonyFauci has warned against excessive #COVID19 #vaccine optimism.
Yes, he says, we may have a product soon. But it might not protect ppl much better than immune syst protects against colds.