Timeliness of vaccination in infants followed by primary-care pediatricians in France.

Vaccination status is more often evaluated by up-to-date vaccination coverage rather than timeliness of immunization. Delaying vaccination may be dangerous during infancy. The aim of this study was to identify the importance of potentially dangerous vaccination delay (previously defined) and determinants of these delays. We conducted a national, prospective, vaccination survey in June 2014, with primary care pediatricians. Children, 2 to 24 months of age, were included. Data about vaccination were extracted from their health books. Additional data were collected through a standardized questionnaire. Vaccine coverage rate and timeliness were calculated. Variables associated with a potentially dangerous vaccination delay as previously defined were determined by a multivariable analysis. Among the 443 included children (mean age 10.8 months, 49% males), 13% to 58% of vaccine doses according to vaccine type were done with a potentially dangerous delay. Globally, 47% of children had at least one potentially dangerous immunization delay. We identified two risk factors of potentially dangerous delayed immunization globally: an increasing age of the child (adjusted odds ratio: 1.2, 95% confidence interval [CI]: 1.1-1.3, p < 10-3), and a working mother (adjusted OR: 2.4, 95% CI: 1.2-4.7, p = 0.01). Despite a good vaccine coverage rate, a large number of children had a potentially dangerous vaccination delay. A high level of vigilance regarding these immunization delays, and particularly to the patients sharing the risk factors of immunization delay identified here, can increase quality and effectiveness of the vaccine protection.

What timing of vaccination is potentially dangerous for children younger than 2 years?

Vaccine-preventable diseases still occur although measured coverage rates at 2 y of age are high. The occurrence of these diseases may be explained in part by untimely, that is, late vaccination. Our objective was to identify potentially dangerous vaccination delays for each dose of each vaccine in children younger than 2 y. A 3-round Delphi process was conducted by e-mail. We recruited 37 French experts in vaccines for children: 16 from the Infovac-France group and 21 from the French study group for pediatric infectious diseases. Items were generated by a literature review for the 10 vaccine doses recommended before 2 y of age. Item reduction in round 1 and 2 and any consensus in round 3 used a 70% consensus cutoff. The mean participation rate was 79%. Delays that should not be exceeded were identified for all vaccine doses. The 70% consensus was reached for 6 of the 10 vaccine doses: 15 d after the recommended date for the first 2 doses of the diphtheria-tetanus-acellular pertussis-inactivated polio vaccine/Haemophilus influenzae b vaccine and for the second dose of the pneumococcal conjugate vaccine, 1 month for the meningococcal C vaccine and for the first dose of the measles-mumps-rubella vaccine, and 11 y of age for completion of the hepatitis B vaccination. This Delphi process identified potentially dangerous vaccination delays for children to the age of 2 y. These can be used as new indicators in further studies of vaccine effectiveness and can help to improve the quality of vaccine protection in children.