Widespread use of the 7-valent pneumococcal conjugate vaccine (PCV7), which appeared in the United States 10 years ago, has reduced the incidence and complications of community-acquired pneumonia (CAP) children under 1 year old. At the same time, the incidence of CAP and its associated complications, including pleural empyema, has clearly increased in older children.

The objective of the study, conducted at the Children's Hospital of Philadelphia (United States) and published in the July issue of Pediatrics, was to determine the frequency of hospitalization for CAP and related complications in children.

A one-stage retrospective cohort study was performed, which used information from the database of hospitalized children for 1997, 2000, 2003 and 2006. The study did not include patients with concomitant diseases. The percentage of changes was calculated using data from 1997 (before the start of PCV7) and 2006 (after the introduction of PCV7).

Total in the database for 1997, 2000, 2003 and 2006. 619,102 cases of hospitalization of children under 18 for PV were recorded. Comparing the total frequency of hospitalizations between 1997 and 2006, there was no statistically significant difference, however, when stratifying patients by age, it was found that in children under 1 year of age, this indicator decreased by 22%, minimal changes were recorded in children aged 1 to 5 years, and in patients 6 to 12 years and over 13 years, on the contrary, the frequency of hospitalizations has increased by 22% and 41% respectively.

The highest frequency of systemic complications (sepsis, respiratory failure) was recorded in children under one year of age, however, compared to 1997, its decrease of 36% was noted in 2006. In all groups of age, the incidence of systemic complications of CAP has remained stable, but the incidence of local (pulmonary) complications, in general, fell from 5.4% in 1996 to 9.6% in 2006 (i.e. 78% ) and was highest in children aged 1 to 5 years.

Thus, after the introduction of PCV7 in 2000, the frequency of systemic complications of community-acquired pneumonia decreased only in children under 1 year of age, and in all other groups, an increase in the incidence of local complications of the CAP was noted.