Statistical analysis:
The main outcomes were the incidence of new SARS-CoV-2 infection in HCWs
before and after vaccination, and the vaccine effectiveness (VE) against
any SARS-CoV-2 infection. The outcomes were analysed for predefined
subgroups according to age, gender, profession, workplace, and
vaccination status. Data were presented as a median with interquartile
range (IQR) of continuous variables and proportions of dichotomous
variables. Univariable and multivariable logistic regression models were
used to assess factors associated with the primary outcomes of
SARS-CoV-2 infection. Details on statistical analysis including sample
size calculations are presented in the Supplementary Material .
Statistical analyses were performed using the Statistica data analysis
software system (TIBCO Software Inc.), version 13. Two-side tests with a
p-value of < 0.05 were considered statistically significant.