Decline in Early Childhood Respiratory Tract Infections in the Norwegian Mother and Child Cohort Study After Introduction of Pneumococcal Conjugate Vaccination

Department of Chronic Diseases, Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.
The Pediatric Infectious Disease Journal (Impact Factor: 2.72). 05/2012; 31(9):951-5. DOI: 10.1097/INF.0b013e31825d2f76
Source: PubMed


The 7-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, whereas evidence of its 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 by 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 (RRs) and 95% confidence intervals (CIs).
For children who had received 3 or more PCV7 immunizations by 12 months of age, the adjusted RRs 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 nonimmunized 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 of age. No association was seen between PCV7 immunization and asthma at 36 months of age.
Reduced incidences of AOM and LRTIs before 36 months of age were observed among children immunized with PCV7 through the childhood immunization program.

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    • "The incidence of IPD declined both in the age group targeted for vaccination as well as in other age groups (as an indirect effect; [3] [4] [5] [6] [7] [8]). Furthermore, the occurrence of acute otitis media and lower respiratory tract infections reduced in children [9], and nasopharyngeal carriage of vaccine serotypes (VT) declined [6,10–12]. Concurrently, an increased incidence of IPD caused by non-vaccine serotypes (NVT; serotype replacement) following PCV7 introduction has consistently been observed in different settings [6] [13] [14]. "
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    ABSTRACT: The introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in the childhood immunisation programme in Norway in 2006 substantially decreased the incidence of vaccine-type (VT) invasive pneumococcal disease (IPD) in all age groups. Additionally, a slight increase in the non-vaccine (NVT) serotype IPD incidence (serotype replacement) was observed. After replacing PCV7 with PCV13 in 2011, a further decrease in IPD incidence is expected. However, the protection by the six additional serotypes opens new nasopharyngeal niches for colonisation, which favours conditions for serotype replacement. Close monitoring of IPD therefore remains important in order to quickly detect changes. In this observational retrospective population-based cohort study we used data notified nationally between 1 January 2004 and 31 December 2012 to determine the VT- and NVT-IPD incidences. The diversity in serotype distribution per year was analysed using the Simpson's index of diversity. Immunisation history of young children was obtained from the Norwegian Vaccination Registry to determine vaccine failure. The incidence of VT-IPD decreased in the targeted (<5 years) and non-targeted (≥5) age groups since PCV7 introduction and further decreased after the replacement with PCV13. Only two cases of vaccine failure were identified. This indicates very high effectiveness of the 2+1 schedules with PCV7 or PCV13 and suggests that non-vaccinated individuals profit through indirect protection. The decrease in incidence of PCV7-IPD in non-targeted age groups became larger in later years, indicating a lag phase for the indirect effects, and suggests that the indirect protection of PCV13 will increase in coming years. The incidence of some NVT, specifically serotypes 23B and 15A, increased after PCV13 introduction. This coincided with an increased Simpson's index of diversity in the targeted age group. As this suggests that serotype replacement is again occurring, continues monitoring of IPD is important so that adaptations to vaccine recommendations can be promptly issued.
    Vaccine 10/2013; 31(52). DOI:10.1016/j.vaccine.2013.10.032 · 3.62 Impact Factor
  • Tidsskrift for Den norske legeforening 01/2012; 132(23):2607-2607. DOI:10.4045/tidsskr.12.1278
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    ABSTRACT: OBJECTIVE: Most primary care clinical guidelines recommend restrictive antibiotic use for childhood infections. We investigated antibiotic prescription rates over time for oral and topical antibiotics for children (≤12 years) in the period 2000-2010. DESIGN, SETTING AND PATIENTS: Longitudinal observational study among children (≤12 years) in a large Dutch general practice database in the period 2000-2010. MAIN OUTCOME MEASURES: Oral and topical antibiotic prescribing rates per year and independent factors influencing antibiotic prescriptions. RESULTS: We analysed 108 555 patient-years during 2000-2010. At least one chronic disease was recorded in 15.8% of patient-years, with asthma most commonly registered. In 14.8% of the patient-years at least one antibiotic was prescribed, while 26.3% of these received two or more prescriptions. Young age and chronic disease had a significant effect on antibiotic prescriptions. Prescriptions for oral and topical antibiotics increased 4.9% and 1.8%, respectively, during 2000-2005 (p<0.001). Prescription rates for oral antibiotics decreased 3.3% during 2006-2010 (p<0.001), while topical prescribing rates remained stable. CONCLUSIONS: One in six children received at least one oral antibiotic prescription per year during 2000-2010. While topical prescription rates steadily increased during 2005-2010 and remained stable during 2006-2010, prescription rates for oral antibiotics increased significantly during the period 2000-2005 and then significantly decreased during the period 2006-2010. As clinical guidelines remained the same over this period, the effects could be contributed to the initiation of the Dutch nationwide pneumococcal vaccination campaign in 2006.
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