Further analyses and sensitivity analyses
We only conducted VE analyses for CoronaVac because few other vaccines
were used in the study population. We evaluated VE during the overall
study period and separately for the period in which SARS-CoV-2 B.1.617.2
(delta variant) was predominant (1 July 2021 - 1 December 2021), which
we defined using WGS data from study samples along with publicly
available data from GISAID. We also performed these two analyses
excluding participants who had a PCR-confirmed SARS-CoV-2 infection
prior to enrolment. In addition, we examined VE since time since
vaccination by comparing VE in the period from 14 – 149 days since the
second vaccine dose to VE ≥150 days since the second vaccine dose.
We performed two sensitivity analyses. For the first, because
reinfection can occur earlier than 90 days, we changed the definition of
“time at risk” from 90 days after infection to 60 days after
infection. For the second, because individuals may be protected as early
as 7 days after their second dose, we defined “fully vaccinated” as 7
days after the second dose rather than 14 days after the second dose.