Reduced risks of influenza-associated hospitalization and complications following vaccination among over 2 million older individuals: a nationwide study using target trial emulation framework

Table 2 Event rates and associated hazard ratios of vaccination versus non-vaccination for clinical complications that occurred during influenza hospitalization

	No. of events	Event rate (no. of events per 1000 person-years)	No. of events	Event rate (no. of events per 1000 person-years)	Adjusted HR^a (95% CI) of vaccinated versus unvaccinated for clinical outcomes	Number needed to be treated
	Vaccinated subjects		Unvaccinated subjects			Number needed to be treated
Influenza-related deaths	128	0.12	188	0.17	0.70 (0.56, 0.88)	26.21
Infectious or pulmonary diseases
Pneumonia	1052	2.61	1196	3.00	0.88 (0.81, 0.96)	39.48
ARDS with ventilator use	15	0.04	44	0.11	0.34 (0.19, 0.61)	17.14
Sepsis	383	0.95	454	1.14	0.85 (0.74, 0.98)	16.14
Cardiovascular diseases
Acute myocardial infarction	31	0.08	52	0.13	0.61 (0.39, 0.95)	25.00
Stroke	51	0.13	95	0.24	0.53 (0.38, 0.75)	12.14
Kidney diseases
Acute kidney injury	129	0.32	170	0.43	0.77 (0.61, 0.96)	14.77

Abbreviations: HR hazard ratio, CI confidence interval, ARDS acute respiratory distress syndrome
^aThe receipt of government-funded health examinations was unbalanced between groups after a two-step propensity score matching and thus was further adjusted in the Cox model
Bold HRs and 95% CIs indicate statistically significant vaccine effectiveness

ISSN: 1741-7015