Pertussis is still common in a highly vaccinated infant population.

To provide epidemiological data on pertussis in a highly vaccinated paediatric population, focusing on the age of the infected children.We analysed data from the regional hospital discharge database on children hospitalised for pertussis in Tuscany, Italy, from January 2000 to December 2012.A total of 279 cases were recorded. The majority of hospitalised children were infants (75.6%), who had the highest rate of complications (24.2%) of any age group and a crude mortality rate of 9.47 per 1000. The overall hospitalisation rate decreased significantly during the study period, from 4.23 to 2.82 per 100 000, but when we analysed the data by age groups, we found notable differences. Hospitalisation rates in the 1- to 4-year-old age group decreased significantly from 2.82 in the year 2000 to zero per 100 000 in 2012 and decreased significantly in the 5- to 9-year-old age group over the same period, from 6.58 to 0.63 per 100 000. Overall hospitalisation rates in the infant group remained high at 53.14 per 100 000, with three peaks due to periodic pertussis outbreaks.Pertussis is still a relevant health concern in infants who are unvaccinated or incompletely immunised, both in terms of morbidity and mortality.