Current evidence on immunity for #COVID19.
My *non-expert* overview
(replying to comment by @taaltree & would love help/comments from actual immunity expert: @florian_krammer or others)
Thread
My *non-expert* overview
(replying to comment by @taaltree & would love help/comments from actual immunity expert: @florian_krammer or others)
Thread
-Strong evidence that most (>90%, possibly higher) of qPCR-confirmed cases develop diverse antibody (Ab) response; in most it is neutralizing; but for some may take 20+ days post-symptom onset to be detected.
medrxiv.org/content/10.110…
medrxiv.org/content/10.110…
medrxiv.org/content/10.110…
medrxiv.org/content/10.110…
medrxiv.org/content/10.110…
medrxiv.org/content/10.110…
-In small fraction of people, no detectable Ab, but detectable T-cell response.
-Diverse T-cell response detected in most cases
medrxiv.org/content/10.110…
cell.com/cell/fulltext/…
-Diverse T-cell response detected in most cases
medrxiv.org/content/10.110…
cell.com/cell/fulltext/…
-As expected, Abs increase, peak & then decay but little data past day 60 (2 months) so plateau vs continuing decay uncertain (refs in last tweet)
Figs: Acute (3-4wk post-inf); convalescent (8wk post-hospital discharge)
Days POS - post symptom onset
Red - more severe cases
Figs: Acute (3-4wk post-inf); convalescent (8wk post-hospital discharge)
Days POS - post symptom onset
Red - more severe cases
-Ab levels can be low and yet be strongly neutralizing.
nature.com/articles/s4158…
-Some patients have detectable viral RNA for 30-50d post symptom onset but aren't infectious to contacts (cdc.go.kr/board/board.es…)
medrxiv.org/content/10.110…
medrxiv.org/content/10.110…
nature.com/articles/s4158…
-Some patients have detectable viral RNA for 30-50d post symptom onset but aren't infectious to contacts (cdc.go.kr/board/board.es…)
medrxiv.org/content/10.110…
medrxiv.org/content/10.110…
-A couple recent reports - not papers - of possible re-infection in which single patient tests + by PCR, is sick, recovers, tests -, then sick 3 months later, test + again (vox.com/2020/7/12/2132…).
-So far just a few individual cases
-So far just a few individual cases
-Data from other coronaviruses
(early article @mlipsitch w/ links to several papers: nytimes.com/2020/04/13/opi…)
-immunity to all 6 viruses wanes, w/ reinfection possible 1 year later for 1 cold virus; Ab persists for SARS-COV-1 in some people for 9-17 years tandfonline.com/doi/pdf/10.108…
(early article @mlipsitch w/ links to several papers: nytimes.com/2020/04/13/opi…)
-immunity to all 6 viruses wanes, w/ reinfection possible 1 year later for 1 cold virus; Ab persists for SARS-COV-1 in some people for 9-17 years tandfonline.com/doi/pdf/10.108…
(Note: Puzzling data in SARS-COV-1 paper (tandfonline.com/doi/pdf/10.108…): Ab titres were higher in people w/ longer duration since infection - opposite of what one would expect)
Big Outstanding Qs:
-What do immune markers (Ab levels, neutralizing immunity, T-cell response, etc.) mean in terms of protection:
-stop infection ("sterilizing immunity")? Reduce probability of infection? (dose dependence?)
-reduce disease severity?
-reduce infectiousness?
-What do immune markers (Ab levels, neutralizing immunity, T-cell response, etc.) mean in terms of protection:
-stop infection ("sterilizing immunity")? Reduce probability of infection? (dose dependence?)
-reduce disease severity?
-reduce infectiousness?
Big Outstanding Qs cont:
-How long will each aspect of protection last? How will this depend on severity of initial infection, age, other traits?
-How will vaccination-derived immunity compare to infection-derived immunity? (markers for several vaccines similar to nat infection)
-How long will each aspect of protection last? How will this depend on severity of initial infection, age, other traits?
-How will vaccination-derived immunity compare to infection-derived immunity? (markers for several vaccines similar to nat infection)
Other related Q:
-What determines enormous differences in disease severity b/w people w/ similar age, pre-existing conditions (1 Hypothesis: Do T-cell response to other coronaviruses affect disease severity?)
cell.com/cell/fulltext/…)
-What determines enormous differences in disease severity b/w people w/ similar age, pre-existing conditions (1 Hypothesis: Do T-cell response to other coronaviruses affect disease severity?)
cell.com/cell/fulltext/…)
Actual answers to @taaltree Qs
Q1: Are papers/reports that immunity is very short lived credible?
My A: Not really. Can't currently assess duration/efficacy of immunity w/ available data. We expect decay of Ab titres but need data from >60d, & other arms of immune system.
Q1: Are papers/reports that immunity is very short lived credible?
My A: Not really. Can't currently assess duration/efficacy of immunity w/ available data. We expect decay of Ab titres but need data from >60d, & other arms of immune system.
Q2: Do we know how likely vaccines are to provide immunity for over a year?
My A: No, we don't. Need more info on both link b/w immune markers and functional immunity plus either actual efficacy of vaccine over time or data on immune markers from vaccines over time. Need 3-6+ mo.
My A: No, we don't. Need more info on both link b/w immune markers and functional immunity plus either actual efficacy of vaccine over time or data on immune markers from vaccines over time. Need 3-6+ mo.
Corrections/comments/clarifications from more qualified people welcome. Will happily delete this thread if directed towards better, comprehensive thread on this topic.
Addition: Another paper today on T-cells & cross reactivity of T-cells from previous exposure to other coronaviruses- need study of role in disease severity.
