Determinants of low measles vaccination coverage in children living in an endemic area.

Measles outbreaks were recently reported in Europe due to low immunization rates. In this scenario, identifying the reasons of no vaccination is crucial to set up strategies to improve immunization rate. A cross-sectional study was conducted to investigate the determinants of missed vaccination in children living in Southern Italy, during the 2016 outbreak. A standardized face-to-face questionnaire was used to record demographic data, immunization status, and reasons for missed vaccination. A total of 1141 children (median age 86 months, male 47.2%) was enrolled, 77.8% of the children were adequately vaccinated for age, 6.3% were incompletely vaccinated for age, and 15.9% did not receive any vaccine dose. Vaccination rate and reasons for not vaccinating significantly varied according to age, with children ≤ 24 months showing the lowest rate (67.8%). Reasons for not vaccinating included fear for side effects (51%), presence of underlying chronic conditions (12.2%), skip scheduled appointment (12.2%), refusal of vaccination (10.3%), acute illnesses (7.2%), and allergy to eggs (4.6%). The presence of underlying condition was a risk factor for inadequate immunization (p < 0.0001). Only 4.7% of conditions were true contraindications to vaccine administration.Conclusion: We reported inadequate measles immunization rate in Southern Italy, with lowest rates in children ≤ 2 years or with underlying conditions. Only a minority had true contraindications to vaccine uptake. Implementation strategies addressed to health-care professionals and families should focus on the reported determinants to increase measles vaccination coverage. What is Known: • Measles is a viral, highly communicable disease, preventable by vaccine. • Measles elimination in Europe failed as demonstrated by outbreaks in several countries, due to low immunization rates. What is New: • Inadequate measles immunization rate due to false contraindications in Southern Italy, with lowest rates in children ≤ 2 years. • The presence of underlying disease is a risk factor for inadequate immunization.