SAN DIEGO, CA—Introduction of early childhood immunization with the pneumococcal conjugate PCV13 vaccine has rapidly reduced the incidence of pediatric consolidated pneumonia (CP) cases in Argentina, according to findings from a prospective single-municipality population-based study reported at IDWeek 2015.

“After three years of PCV13 vaccine introduction into Argentina’s immunization schedule, a rapid and significant reduction in CP incidence was observed, mainly in infants [younger than] 1 year old in 2012 and [younger than] 2 years old in 2013,” reported study coauthor Julia Bakir, MD, R. Gutierrez Children Hospital, Buenos Aires, Argentina, and coauthors.

The vaccine’s effectiveness became evident among children of older ages during the third year of vaccine introduction, they noted.

PCV13 was introduced into Argentina’s routine immunization program in a 2+1 dose schedule for children younger than age 2 years, in January 2012.

The study authors analyzed all inpatient and outpatient children younger than age 5 years who had clinical signs of pneumonia at referral hospitals between January 2012 and December 2014. Clinical and radiological evaluation was performed using WHO criteria, the coauthors reported. Annual CP incidence was compared between the 3-year vaccination period (2012–2014) and a 3-year prevaccination-era baseline (2003–2005).

“Vaccination coverage was high except the third dose in 2012 in the municipality studied,” Dr. Bakir reported.

CP became less common between the two study periods: 611 cases in the prevaccination years vs. 401 during the vaccination period (P<0.001), representing 56% and 45.9% of all clinical pneumonia cases, respectively, Dr. Bakir reported. The CP incidence per 100,000 children age <5 years declined significantly between the study periods and during the vaccination period, from 750 in prevaccination years to 561 in 2012, 453 in 2013, and 302 in 2014.

“For children 24–59 months the reduction was 53.3% in 2014,” Dr. Bakir noted.

“The surveillance of the burden of disease and serotype distribution is crucial to evaluate the local impact,” the coauthors noted.