Successes and failures in vaccine delivery: evaluation of the immunization delivery system in Puerto Rico.

The objective of this study was to evaluate immunization delivery and determine reasons for low coverage among preschool-age public clinic attendees in Puerto Rico. In 25 randomly selected clinics, coverage and missed immunization opportunities were assessed in 273 children aged 2 to 59 months, exist interviews were conducted with parents, and providers were interviewed. Two neighborhoods close to the clinics were surveyed to determine parental knowledge about immunizations, and the vaccination status of children in these neighborhoods was assessed. Two hundred seventy-three clinic attendees were interviewed. Among 229 (84%) with vaccination cards, only 126 (55%) had received all indicated vaccines by completion of the clinic visit. Forty-five percent of children with cards in the household survey were not up-to-date. Of 171 (75%) clinic attendees eligible for vaccination at the visit, 118 (69%) missed one or more immunizations at the visit. In addition, half of all children had previously missed one or more immunizations when they had received another vaccine. Missed opportunities occurred because of nonavailability of vaccines, lack of integration of services, provider misconceptions about contraindications, and failure to administer vaccines simultaneously. Other problems included barriers to immunization services and lack of information and education activities. It is concluded that deficiencies in immunization delivery substantially delay immunization and reduce coverage.