Impact on respiratory tract infections of heptavalent pneumococcal conjugate vaccine administered at 3, 5 and 11 months of age

Table 4 Frequency of acute otitis media (AOM) during follow-up.

Episodes	PCV-7 group (n = 811)	Control group (n = 744)	RR	95% CI	P
Total number of AOM cases during follow-up	637	698
Episodes/100 child-years	39.2	46.9	0.83	0.61–1.02	0.02
AOM in children aged 6–12 months	156	156
Episodes/100 child-years	38.4	41.9	0.91	0.75–1.20	0.06
AOM in children aged 13–18 months	195	220
Episodes/100 child-years	48.0	59,1	0.81	0.76–1.02	0.04
AOM in children aged 19–24 months	144	162
Episodes/100 child-years	35.5	43.5	0.82	0.62–1.24	0.04
AOM in children aged 25–30 months	142	160
Episodes/100 child-years	35.0	43.0	0.81	0.61–1.20	0.04