Bivalent mRNA vaccine effectiveness against COVID-19 among older adults in Japan: a test-negative study from the VENUS study

Table 4 Absolute or relative VE of bivalent vaccines according to infection history

	Infection history
	No (n = 18,528)		Yes (n = 1,278)
	Absolute VE^a, % (95% CI)	Relative VE^a, % (95% CI)	Absolute VE^a, % (95% CI)	Relative VE^a, % (95% CI)
Vaccination status
Unvaccinated	Ref	—	Ref	—
≥ 2 monovalent doses	17.8 (3.4, 30.0)	Ref	47.7 (-32.9, 79.5)	Ref
≥ 2 monovalent doses plus a bivalent dose	33.1 (20.0, 44.0)	18.6 (9.9, 26.5)	47.6 (-57.1, 82.5)	-0.3 (-127.4, 55.8)

Logistic regression analyses with cluster robust standard errors at the individual level were conducted to estimate the ORs and 95% CIs for testing positive according to the vaccination status. VE was defined as (1 − OR) × 100%
Abbreviations: VE vaccine effectiveness, CI confidence interval, OR odds ratio
^aAdjusted for sex, age group, number of comorbidities, residential municipality, and test week

ISSN: 1471-2334