TABLE 2. COVID-19 vaccine effectiveness* against laboratory-confirmed COVID-19–associated hospitalizations and critical illness^† among adults aged ≥18 years, by age group and immunocompromise status — seven states,^§ September 2022–April 2023.

Clinical status/Age group, yrs/Vaccine type and doses received, interval since receipt of BV dose	Without documented immunocompromising conditions				With documented immunocompromising conditions
	Total	Positive SARS-CoV-2 test result, no. (%)	Median interval since last dose, days (IQR)	VE, % (95% CI)	Total	Positive SARS-CoV-2 test result, no. (%)	Median interval since last dose, days (IQR)	VE, % (95% CI)
Hospitalization
≥18
Unvaccinated (Ref)	15,514	1,791 (11.5)	NA	Ref	3,109	314 (10.1)	NA	Ref
MV only	37,269	3,988 (10.7)	376 (270 to 505)	21 (16 to 26)	11,140	1,134 (10.2)	355 (237 to 474)	3 (−12 to 16)
BV, 7–59 days earlier	4,857	327 (6.7)	34 (21 to 47)	62 (57 to 67)	1,612	143 (8.9)	33 (19 to 46)	28 (10 to 42)
BV, 60–119 days earlier	5,191	486 (9.4)	87 (73 to 103)	47 (41 to 53)	1,829	140 (7.6)	88 (74 to 104)	41 (26 to 53)
BV, 120–179 days earlier	3,310	315 (9.5)	144 (132 to 159)	24 (12 to 33)	1,244	103 (8.3)	144 (131 to 159)	13 (−13 to 33)
18–64
Unvaccinated (Ref)	8,033	591 (7.4)	NA	Ref	NA	NA	NA	NA
MV only	12,368	821 (6.6)	403 (306 to 534)	17 (7 to 26)	NA	NA	NA	NA
BV, 7–59 days earlier	959	38 (4.0)	33 (21 to 45)	61 (44 to 72)	NA	NA	NA	NA
BV, 60–119 days earlier	935	66 (7.1)	86 (72 to 101)	25 (1 to 43)	NA	NA	NA	NA
BV, 120–179 days earlier	561	31 (5.5)	143 (131 to 158)	16 (−24 to 43)¶	NA	NA	NA	NA
≥65
Unvaccinated (Ref)	7,481	1,200 (16.0)	NA	Ref	NA	NA	NA	NA
MV only	24,901	3,167 (12.7)	362 (245 to 484)	24 (18 to 29)	NA	NA	NA	NA
BV, 7–59 days earlier	3,898	289 (7.4)	35 (21 to 48)	64 (58 to 68)	NA	NA	NA	NA
BV, 60–119 days earlier	4,256	420 (9.9)	87 (73 to 103)	51 (45 to 57)	NA	NA	NA	NA
BV, 120–179 days earlier	2,749	284 (10.3)	145 (132 to 159)	27 (15 to 37)	NA	NA	NA	NA
Critical illness**
≥18
Unvaccinated (Ref)	14,090	367 (2.6)	NA	Ref	2,881	86 (3.0)	NA	Ref
MV only	33,925	644 (1.9)	375 (269 to 505)	31 (21 to 40)	10,263	257 (2.5)	354 (235 to 474)	16 (−10 to 36)
BV, 7–59 days earlier	4,579	49 (1.1)	34 (21 to 47)	69 (57 to 77)	1,501	32 (2.1)	33 (19 to 46)	40 (7 to 61)¶
BV, 60–119 days earlier	4,790	85 (1.8)	86 (73 to 103)	46 (30 to 58)	1,725	36 (2.1)	88 (74 to 104)	43 (14 to 63)
BV, 120–179 days earlier	3,028	33 (1.1)	144 (132 to 159)	50 (26 to 66)	1,155	14 (1.2)	144 (131 to 159)	53 (13 to 75)¶

Abbreviations: BV = bivalent; MV = monovalent; NA = not applicable; Ref = referent group; VE = vaccine effectiveness.

* VE was calculated as (1 − odds ratio) x 100%, estimated using a test-negative case-control design, adjusted for age, sex, race and ethnicity, geographic region, and calendar time (days since January 1, 2021).

^† Patients were considered to have critical illness if they were admitted to an intensive care unit or died. Death was identified at each individual site and was defined as a death while hospitalized or ≤28 days after admission.

^§ California (September 13, 2022–April 21, 2023), Indiana (September 13, 2022–April 12, 2023), Minnesota and Wisconsin (September 13, 2022–April 21, 2023), Oregon and Washington (September 13, 2022–April 14, 2023), and Utah (September 13, 2022–April 21, 2023).

^¶ These estimates are imprecise, which might be because of a relatively small number of persons in each level of vaccination or case status. This imprecision indicates the actual VE could be substantially different from the point estimate shown, and estimates should therefore be interpreted with caution. Additional data accrual could increase precision and allow appropriate interpretation.

** For VE against critical illness, case-patients were persons admitted to an intensive care unit or who experienced death associated with COVID-19, and control patients were persons hospitalized without COVID-19.