Sinovac's CoronaVac, in healthcare workers in Uni of São Paulo hospital vs the city: considerable uncertainty, but suggests ca 50% effective despite high level of variants of concern 2 wks after dose 2, rising to around 70% some weeks later...1/n medrxiv.org/content/10.110… Preprint 
.For the healthcare workers, "cases" = Covid-19, symptomatic & confirmed. Around 22,000 healthcare workers were vaccinated. If they had symptoms, they left work & got tested... 2/n
...The data are compared with the officially published rates of Covid-19 in the city (presumably not necessarily all symptomatic). Early testing was inadequate as the rate of confirmed cases didn't track with deaths. Later on though the estimates for the city more reliable...3/n
...A major wave of Covid-19 hit the city soon after the healthcare workers (HCWs) had been vaccinated. They estimated how many HCWs you'd expect to get sick, but they caution their model had weaknesses, making the later weeks after vax particularly uncertain...4/n
...They tested a random sample of 142 of the HCWs with Covid-19: they detected variants of concern in 67 (47%) - 57 of those 67 were P1 ("Brazil"), 5 were B.1.1.7 ("UK"), & 5 weren't identified...5/n
...Cautions esp for later weeks, estimated efficacy against symptomatic Covid-19 (large part P1):
- After 2 wks: 50.7% (CI 33-63)
- 3 wks: 51.8% (CI 30-66)
- 4 wks: 68.4% (CI 51-81)
- 5 wks: 73.8% (CI 57-85)
6 unvaxed HCWs hospitalized (1 died) vs 3 part/full vax (0 died)
6/6
- After 2 wks: 50.7% (CI 33-63)
- 3 wks: 51.8% (CI 30-66)
- 4 wks: 68.4% (CI 51-81)
- 5 wks: 73.8% (CI 57-85)
6 unvaxed HCWs hospitalized (1 died) vs 3 part/full vax (0 died)
6/6
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