Table 2. Effectiveness of Two Doses of BNT162b2 Vaccine before and during Proxy Omicron Period.^*.

Variable	Vaccine Effectiveness (95% CI)
	Comparator Period	Proxy Omicron Period
	%
Overall estimate	93 (90–94)	70 (62–76)
Sensitivity analyses of PCR results
Patients with S-gene target failure	—	69 (48–81)
Patients in Gauteng province	—	70 (59–78)
Patients with Covid-19 symptoms	—	50 (35–62)

^*The overall estimates of vaccine effectiveness were calculated according to a test-negative design after adjustment for confounders. The three sensitivity analyses included the results of polymerase-chain-reaction (PCR) tests showing S-gene target failure (as an indication of omicron infection), PCR results obtained only from patients in Gauteng province, and PCR results obtained only from patients who had been hospitalized (i.e., symptomatic population).