Table 4.

COVID-19 event rates and estimated vaccine effectiveness 28 days after vaccination or matching during beta variant (B.1.351)-dominant and delta variant (B.1.617.2)-dominant periods

	COVID-19-related hospital admission			COVID-19-related hospital admission requiring critical or intensive care			COVID-19-related death
	Vaccinated (events/person-years)	Unvaccinated (events/person-years)	Vaccine effectiveness (95% CI)	Vaccinated (events/person-years)	Unvaccinated (events/person-years)	Vaccine effectiveness (95% CI)	Vaccinated (events/person-years)	Unvaccinated (events/person-years)	Vaccine effectiveness (95% CI)
Scheme A plus B
Beta variant-dominant period	33/13 982	89/13 960	62 (42 to 76)	12/13 992	24/13 985	49 (8 to 77)	1/13 996	12/13 991	86 (57 to 100)
Delta variant-dominant period	268/29 788	808/29 492	67 (62 to 71)	51/29 802	232/29 525	78 (71 to 84)	27/29 807	151/29 534	82 (74 to 89)
Scheme A
Beta variant-dominant period	11/5929	29/5919	56 (43 to 68)	0/5931	6/5922	..	0/5931	5/5922	..
Delta variant-dominant period	142/14 199	416/13 854	67 (60 to 72)	19/14 212	105/13 880	82 (72 to 90)	11/14 214	70/13 885	85 (74 to 94)
Scheme B
Beta variant-dominant period	22/8052	61/8041	62 (39 to 79)	12/8061	19/8064	32 (−27 to 73)	1/8064	7/8069	..
Delta variant-dominant period	127/15 590	392/15 638	68 (61 to 74)	32/15 590	127/15 644	75 (64 to 84)	16/15 593	81/15 651	80 (69 to 89)

The beta variant-dominant period was defined as Feb 17 to May 17, 2021, and the delta variant-dominant period as May 18, 2021, until data cutoff (July 17, 2021).