Pertussis epidemic despite high levels of vaccination coverage with acellular pertussis vaccine

espanolIntroduccion Se describe la epidemia de tos ferina en el ano 2011 solo en casos confirmados. Se analizan datos sobre diagnostico, epidemiologia y antecedentes vacunales que podrian explicar las tendencias de la enfermedad. Metodos Estudio descriptivo de los casos confirmados de tos ferina notificados durante 2011 en la region del Valles (poblacion 1.283.000habitantes). Los criterios de laboratorio para confirmacion de un caso incluyen el aislamiento de Bordetella pertussis mediante cultivo en una muestra clinica o deteccion de B.pertussis por PCR en muestras nasofaringeas. Resultados Fueron declarados 421 casos confirmados, siendo la incidencia mas alta de los ultimos 10anos (33casos por 100.000personas/ano en 2011). La mayor tasa de incidencia fue en ninos Conclusion A pesar de los altos niveles de cobertura vacunal, la circulacion de la tos ferina no se puede controlar del todo. Los resultados ponen en duda la eficacia de los programas de inmunizacion actuales. EnglishIntroduction We describe the pertussis epidemic, based only on confirmed whooping cough cases. We have analyzed data on the diagnosis, epidemiology and vaccine history in order to understand the factors that might explain the trends of the disease. Methods A descriptive study of the confirmed pertussis cases reported during 2011 in the Valles region (population 1,283,000). Laboratory criteria for confirmed pertussis cases include isolation of Bordetella pertussis from a clinical specimen or detection of B. pertussis by PCR in nasopharyngeal swabs. Results A total of 421 pertussis confirmed cases were reported, which was the highest incidence reported in the last decade (33 cases/100,000 people/year in 2011). The highest incidence rate was among infants less than 1 year old (448/100,000), followed by children 5–9 years old (154/100,000). Pertussis cases aged 2 months–1 year were 90% vaccinated following the current DTaP schedule for their age group in Catalonia, and cases of 5–9 years were 87% fully vaccinated with 5 doses of DTaP vaccine. There were no deaths, although 8% of cases were hospitalized. Pertussis was more severe in infants, 30% required hospitalization despite having received the vaccine doses corresponding to their age. Children of 5–9 years were most often identified as primary cases in households or school clusters. Conclusion Despite high levels of vaccination coverage, pertussis circulation cannot be controlled at all. The results question the efficacy of the present immunization programmes