Thread by @dockaurG

Pls read #SARSCoV2 immunology🧵& subthreads for what media & “experts” are not telling you

Facts
-we have some pre-existing cross-protective immunity
-basing herd immunity only on antibodies omits strong Tcell immunity
-vaccine candidates not effective b/c don’t elicit IgA prodn

https://twitter.com/dockaurG/status/1275774070815105024

2/ Last week, researchers in Sweden and Germany also found strong T-cell responses to #SARSCoV2 which bode well for long-term immunity & found pre-existing cross-protective immunity: findings are consistent with the original US Cell study published in May.

https://twitter.com/dockaurg/status/1261379543249629184

3/ We now have three independent #SARSCoV2 studies, from teams of scientists in three different countries, all concluding the same thing:

“#COVID19 Herd Immunity Is Much Closer Than Antibody Tests Suggest”
reason.com/2020/07/01/cov…

4/Swedish study found “#SARSCoV2-specific memory Tcells will likely prove critical for longterm immune protection against #COVID19. SARSCoV2-specific Tcells detectable in antibody-seronegative family members & ppl w/history of asymptomatic or mild COVID19”
biorxiv.org/content/10.110…

5/ Swedish study above concluded “#SARSCoV2 elicits robust memory T-cell responses akin to those observed in context of successful vaccines, suggesting that natural exposure or infection may prevent recurrent episodes of severe #COVID19 also in antibody-seronegative individuals.”

6/ German study “detected #SARSCoV2 cross-reactive Tcells in 81% of unexposed individuals.” Study found “detection of specific Tcell responses even in donors w/out antibody responses, thereby providing evidence for Tcell immunity upon #COVID19 infection”
▶️researchsquare.com/article/rs-353…

7/ All very positive news reaffirming significant Cell study findings. We’re closer to herd immunity than we think: we’re grossly underestimating pre-existing cross-protective immunity to #SARSCoV2 & we’re not measuring strong Tcell responses which bode well for longterm immunity

8/ @NatureMedicine study by Dutch scientists found Vitamin D imp for effective Tcell immune responses. We know Tcell immunity plays significant role in overcoming #SARSCoV2 infection. This could help explain why POC disproportionately affected by #COVID19.
nature.com/articles/ni.18…

9/ VitD regulates expression of Phospholipase C isozyme PLC-γ1 in naive Tcells & key to Tcell responsiveness in humans. POC greater risk of VitD deficiency. Poor primary Tcell response can affect immune responses to viral infections, incl influenza & coronaviruses like #SARSCoV2.

10/ Oxford scientists reinforce imp of pre-existing T-cell immunity & that we’re closer to #SARSCoV2 herd immunity than we think.

Results “suggest sufficient herd-immunity may already be in place to substantially mitigate a potential #COVID19 second wave”
medrxiv.org/content/10.110…

11/ British scientists published yesterday in @SciImmunology

“It is clear from these datasets that some ppl who lack an antibody response to #SARSCoV2 show strong specific Tcell immunity. This pattern is predicted by the experience with SARSCoV1 & MERS”
▶️immunology.sciencemag.org/content/immuno…

12/From British scientists in above @SciImmunology: interactions btwn #SARSCoV2 infected cells, antigen-presenting cells, CD4 & CD8 Tcells

SARSCoV2-reactive CD4 Tcells are Th1-like: secrete IFNγ, TNFα, IL2. CD8 Tcells secrete similar cytokines but also lyse infected target cells

13/ Singapore scientists published significant research this week in @NatureMedicine showing

“#SARS-recovered pts still possess long-lasting memory Tcells reactive to SARS 17 years after 2003 outbreak, which displayed robust cross-reactivity to #SARSCoV2”
nature.com/articles/s4158…