Table 2.

Cohort studies of influenza vaccine effectiveness (VE) for preventing pneumonia- or influenza-related hospitalization among the community-dwelling elderly.

Author	Publication year	Country	Study periods	Subject age (years)	Sample size	VE (95% CI)
Arriola et al.22	2017	United States	2013–2014	≥65	1,588	−2 (−27 to 19)
Arriola et al.25	2015	United States	2012–2013	65–74	1,296	20 (−6 to 39)
				≥75	2,680	−2 (−23 to 16)
Song et al.14	2015	South Korea	2013–2014	≥65	573	55 (29 to 71)
Simpson et al.26	2013	United Kingdom	2000–2009	≥65	1,358	12 (−2 to 24)
Baxter et al.27	2010	United States	1997–2008	≥65	4,018,380	9 (3 to 14)
Nichol et al.29	2007	United States	1990–2000	≥65	713,812	27 (23 to 32)
Nordin et al.30	2001	United States	1996–1997	≥65	124,582	20 (5 to 31)
			1997–1998		158,454	24 (14 to 34)
Nichol e al.32	1999	United States	1990–1996	≥65	147,551	39 (26 to 52)
Baker et al.38	1980	United States	1968–1969	≥65	9,760	2 (−23 to 13)
			1972–1973		10,740	74 (−8 to 94)