The seven-valent pneumococcal conjugate vaccine (PCV7) was introduced into the Norwegian Childhood Immunization Program in 2006. A substantial effectiveness of PCV7 immunization against invasive pneumococcal disease has been demonstrated, while evidence of the impact on respiratory tract infections are less consistent.
This study included children participating in the Norwegian Mother and Child Cohort Study, which recruited pregnant women between 1999 and 2008. Maternal report of acute otitis media (AOM), lower respiratory tract infections (LRTIs) and asthma in the child was compared with PCV7 immunization status, as obtained from the Norwegian Immunization Registry. Generalized linear models with the log link function were used to report adjusted relative risks (RR) and 95% confidence intervals (CI).
For children who had received three or more PCV7 immunizations by 12 months of age, the adjusted relative risks of AOM and LRTIs between 12 and 18 months were 0.86 [95% CI: 0.81, 0.91] and 0.78 [95% CI: 0.70, 0.87] respectively, when compared with non-immunized children. A reduced risk of AOM, RR 0.92 [95% CI: 0.90, 0.94], and LRTIs, RR 0.75 [95%CI: 0.71, 0.80], between 18 and 36 months of age was also identified among children who had received 3 or more immunizations by 18 months. No association was seen between PCV7 immunization and asthma at 36 months of age.
Reduced incidence proportions of AOM and LRTIs before 36 months of age were observed among children immunized with PCV7 through the childhood immunization program.