Immunization coverage and timeliness of vaccination in Italian children with chronic diseases.

Since children with chronic diseases represent a primary target for immunization strategies, it is important that their immunization coverage and timeliness of vaccines is optimal. We performed a study to measure immunization coverage and timeliness of vaccines in children with type 1 diabetes, HIV infection, Down syndrome, cystic fibrosis, and neurological diseases. A total of 275 children aged 6 months-18 years were included in the study. Coverage for diphtheria-tetanus-pertussis (DTP), polio (Pol), and hepatitis B (HBV) vaccines approximated 85% at 24 months, while measles-mumps-rubella (MMR) coverage was 62%. Immunization coverage for seasonal influenza was 59%. The analysis of timeliness revealed that there was heterogeneity among children with different chronic diseases. A proportional hazard model showed that children with HIV infection had the longest time to complete three doses of DTP, Pol, and HBV, and those with neurological diseases received the first dose of MMR later than the other categories. Causes of missing or delayed vaccination mostly included a concurrent acute disease. Children with chronic diseases should be strictly monitored for routine and recommended vaccinations, and health care providers and families should be properly informed to avoid false contraindications.