Bordetella pertussis in hospitalised children and adolescents: the impact of vaccination delay, Tuscany, Italy, 2016 to 2024.

BACKGROUNDPertussis is a highly contagious respiratory infection caused by Bordetella pertussis. Vaccination against pertussis is included in the Italian vaccination programme with three doses administered at 3, 5 and 11 months, booster doses at 6 and 12-18 years, and every 10 years. Vaccination coverage in Tuscany is high among infants (97.7% vs 94.7% national average at 24 months) and adolescents (75.8% vs 68.4% national average at 16 years).AIMWe aimed to investigate case numbers, vaccination status and time points for vaccination of children and adolescents hospitalised for pertussis.METHODSWe collected data on children and adolescents aged ≤ 16 years and hospitalised for laboratory-confirmed pertussis in 2016-2024 at a tertiary hospital in Tuscany.RESULTSA total of 384 children and adolescents were hospitalised in 2016-2024. Annual case numbers increased from an average of 28.2 cases in 2016-2019 to 259 cases in 2024, with 136 (52.5%) cases in adolescents. Of the 107 cases aged 12-16 years, 93 (86.9%) were unvaccinated or had not received the second booster. A considerable time gap between the earliest eligible day for vaccination and hospitalisation was observed. In infants, a median of 31 days (interquartile range (IQR): 10-131 days) was noticed for the first dose, 44 days (IQR: 22-70 days) for the second and 53 days for the third. In 12-16-year-olds, a median of 395 days (IQR: 236-717) was seen for the second booster.CONCLUSIONAdministering adolescent booster doses earlier, vaccinating at the earliest eligible time points, and promoting timely vaccination through targeted communication campaigns may reduce pertussis-related hospitalisations.