Thread by @MonicaGandhi9

Another study showing re-infection rare after natural infection. "Establishing whether reinfection is typically symptomatic or asymptomatic, whether reinfected individuals are infectious, and expected duration" of immunity from infection vs vax paramount
thelancet.com/journals/lance…

From awesome SIREN study, which is prospective cohort study in staff working in NHS hospitals across UK (giving us great info about vaccine effectiveness too). Lancet asked for "prior evidence" before this study & re-infection up to Nov 15, 2020 rare - 24 documented infections.

25,661 participants with linked data on antibody and PCR included. If had prior infection (documented by antibodies, T cells not measured), re-infection rare. 1859 new infections: 1704 in the negative cohort & 155 reinfections in the positive cohort. Symptoms among re-infections?

One half (76) of asymptomatic (lots of asymptomatic screening); 1/3 (50) with typical COVID-19 symptoms; the others (28) with atypical symptoms. 17383 participants in negative cohort so that is 0.4% rate of symptomatic COVID-19 (generously including those with atypical symptoms)

if you have had #covid19, very rare to get re-infection. B117 increased prevalence during study but didn't change finding. So, 93% lower risk of COVID infection after natural infection, after 7 months of follow-up (7 months); implications for long-lasting immunity with vax too

Again, I don't think we know if vaccines will increase durability of immunity after #covid19 but I think compromise is to take one dose - see this thread:
threadreaderapp.com/thread/1378768…