Effect of age at vaccination on the measles vaccine effectiveness and immunogenicity: systematic review and meta-analysis

Table 2 Seropositivity risk after two doses of measles vaccine by age at first vaccination

Author, year (strain) (ref)	N^a	Seropositivity dfn^b	Seropositivity risk by age at MVC1 [95%CI]
Author, year (strain) (ref)	N^a	Seropositivity dfn^b	< 6	6	7–8	9	10–11	12
Soerensen, 1985 (Schwarz) [92]	1111	+			0.80 [0.77–0.82]	0.90 [0.83–0.98]	0.96 [0.90–1]
McGraw, 1986 (Moraten) [85]	52	+			0.95 [0.85–1]	0.89 [0.76–1]		1.00 [−]
Gans, 2001 (Moraten) [6]	31	+		1.00 [−]		1.00 [−]
Gans, 2004 (Moraten) [93]	50	+		0.86 [0.74–0.99]		0.90 [0.78–1]
Vesikari, 2012 (Moraten) [69]	1364	+				0.95 [0.93–0.97]	0.98^c [0.96–0.99]	0.99 [0.97–1]
Martins, 2014 (EZ) [74]	655	+	0.97 [0.95–0.99]			0.99 [0.98–1]
He, 2014 (Hu191) [70]	206	+			1.00^d [−]			1.00 [−]
Youwang, 2001 (Hu191) [132]	76	4-fold		0.40 [0.15–0.65]	0.52^e [0.40–0.65]

Abbreviations: CI Confidence interval, E-Z Edmonston-Zagreb, NR Not reported, MCV1 dose one of measles-containing vaccine
^a Number of cases for the calculation of the age effect
^b + = seropositivity among all participants; 4-fold = fourfold increase in antibody titers
^c 11 months
^d 8 months
^e 8 to 15 months