Hospitalized children with pneumonia in Uruguay: pre and post introduction of 7 and 13-valent pneumococcal conjugated vaccines into the National Immunization Program.

INTRODUCTION: Streptococcus pneumoniae pneumonia burden in children was poorly defined in Uruguay. A three-year population-based surveillance demonstrated the impact of the pneumonia in hospitalized children of less than five years of age. To control these diseases in March 2008, Uruguayan health authorities decided to incorporate PCV7 to the National Immunization Program administered at 2, 4 and 12 months of age (2+1 schedule).
OBJECTIVE: To compare the incidence of consolidated pneumonia hospitalization in children less than five years of age before and after pneumococcal conjugate vaccine implementation.
METHODS: Same methodology of the prevaccination study was employed. The surveillance was carried out at the same four hospitals covering a population of 229,128 inhabitants (2004 Census) of whom 10.2% were under five years of age. Clinical data, vaccination status and digitization of their chest X-rays were recorded. A pediatric radiologist blinded to the clinical diagnosis interpreted the digital images according WHO definitions. Bacterial etiology was investigated in blood and/or in pleural fluid.
RESULTS: Between January 1st 2009 and June 30th 2011 patients were enrolled. Out of 23,445 children<5 years of age, 1224 were hospitalized with pneumonia (430 consolidated pneumonias and 794 non consolidated pneumonias). Pleural effusion was recorded in 89 patients. In 48 consolidated pneumonias S. pneumoniae etiology was recognized. Post vaccination incidence rate of consolidated pneumonia in patients aged 12-23 months showed a significant reduction (44.9%) if we compare it with the incidence of pneumonia hospitalization in the previous study. In March 2010, PCV13 replaced PCV7. Compliance of PCV7/13 globally was 92% but the vaccination status varied among the surveyed patients because two catch-ups were carried out in addition to the routine cohort vaccination. From 2009 1st semester to 2011 1st semester incidence rates decline reached 59%.
CONCLUSION: To date, the ongoing surveillance documented a significant decline on incidence of hospitalizations for consolidated pneumonia in children younger than 24 months of age, confirming the success of the 2+1 vaccination schedule.