Surveillance of hospitalized and outpatient cases of pertussis in Catalonia from 2003 to 2009.

Pertussis is a vaccine-preventable disease that generates a large number of cases and hospitalizations. In Catalonia, the vaccination schedule includes three doses of vaccine at 2, 4 and 6 mo and two booster doses at 18 mo and 4-6 y. In 2002, DTPw was replaced by DTPa. The aim of this study was to determine how the vaccination status affects pertussis hospitalizations. Cases were obtained from the epidemiological surveillance system of the Generalitat of Catalonia from 2003 to 2009. Hospitalization, immunization status and type of vaccine received in reported cases were analyzed. OR and 95% confidence intervals (CI) were calculated. To control the effect of age (< 6 mo and ≥ 6 mo) Mantel-Haenszel OR (ORMH) were calculated; statistical significance was established as p < 0.05. During the study period, 1538 cases were reported. Cases below vaccination age (< 2 mo) were excluded. A total of 265 cases were hospitalized: 137 (51.7%) had no vaccine administrated, 104 (39.2%) were correctly vaccinated according to age and 24 (9.1%) were poorly vaccinated. Correct vaccination protected against hospitalization (ORMH: 0.33; 95%CI: 0.23-0.47). Of hospitalized cases, 38 (14.3%) had received DTPw and 91 (34.2%) DTPa. Both vaccines were effective in avoiding hospitalization, and comparison showed no differences (ORMH: 0.73; 95%CI: 0.46-1.14). We highlight the importance of a correct follow-up immunization schedule in reducing the number of cases and hospitalizations.