Using registry data to evaluate the 2004 pneumococcal conjugate vaccine shortage

Background: The most recent pneumococcal conjugate vaccine (PCV7) shortage Occurred between December 2003 and September 2004. To ensure vaccination of the highest-risk children, the Centers for Disease Control and Prevention recommended that providers delay administration of the third and fourth doses of vaccine to healthy children. We used Michigan Child Immunization Registry (MCIR) data collected from September 1, 2001 to November 30, 2004 to evaluate changes in PCV7 coverage. Methods: Vaccination and demographic data from MCIR were reviewed for 420,733 children born between September 2001 and August 2004. Main outcome measures were the proportion of children who received the third dose of PCV7 by 7 months of age and the fourth dose of PCV7 by 16 months of age. Vaccine coverage for measles, mumps, and rubella vaccine (MMR) and diphtheria, tetanus, and acellular pertussis vaccine (DTaP) was used for comparison, as these vaccines were abundant during this time period and their administration schedule is the same as the third and fourth doses of PCV7, respectively. Data analysis was conducted in spring 2005. Results: Coverage for the third dose of DTaP and the first dose of MMR remained steady, while PCV7 coverage for the third dose dropped from 29% to 11%, and the fourth dose dropped from 27% to 22% in the month following the recommendations to defer doses. Coverage returned close to pre-shortage levels shortly after the recommendations to resume the normal schedule. PCV7 coverage trends were similar for children seen in the private or public sector. Conclusions: Registry data can be useful for evaluating vaccination coverage trends during a shortage. Our findings suggest that providers were compliant with recommendations to alter vaccine administration during the shortage.