Incidence of admissions due to pneumonia in children under 24 months old before and after the introduction of the 10-valent pneumococcal conjugate vaccine into the National Immunization Program of Chile

Abstract

Introduction: Streptococcus pneumoniae is the leading cause of bacterial pneumonia in children, especially in the hospitalized population. The 10-valent pneumococcal vaccine was included in the National Immunization Program of Chile in 2011. 

This study aims to evaluate the incidence of pneumonia in hospitalized children < 24 months of age in the Luis Calvo Mackenna Hospital before and after the introduction of the pneumococcal vaccine into the National Immunization Program.

Patients and Methods: Passive surveillance study. Patients < 24 months with discharge diagnosis of bacterial pneumonia from Luis Calvo Mackenna Hospital were studied between 2009 and 2013. Data were obtained from the Luis Calvo Mackenna Hospital's Statistical Service. The incidence of pneumonia was evaluated in the pre-vaccination period (2009-2010) and in the post-vaccination period (2012-2013).

Results: During the study period, an average of 4,321 discharges/year was observed in children < 24 months (range: 3,587-4,702), with a significant decrease from pre- to post-vaccination vaccine period (4,644 vs 4,013, P < .001). The average incidence of pneumonia ranged from 3.4/100,000 to 1.5/100,000 in the pre- and post-vaccine period, respectively (P = .009), with an annual mean of 157 cases of pneumonia in the pre-vaccine period, and 62 cases in the postvaccine period (P < .001) and a decrease in incidence between the two periods of 56%.

Conclusion: This study confirms information previously obtained in other countries, which show a decrease in the incidence of pneumonia associated with the implementation of a pneumococcal vaccine at the population level. Ongoing surveillance is required to evaluate if this effect is maintained over time and expands to older populations.