Differential effects of the DTaP and MMR vaccine shortages on timeliness of childhood vaccination coverage

Objectives. We determined the effect of diphtheria and tetanus toxoids and acellular pertussis vaccine (DTaP) and measles, mumps, rubella (MMR) vaccine shortages on timeliness of the third dose of DTaP (DTaP3), the fourth dose of DTaP (DTaP4), and the first dose of MMR (MMR1) among subgroups of preschool children. Methods. Data from the 2001 and 2002 National Immunization Surveys were analyzed. Children age-eligible to receive DTaP3, DTaP4, or MMR1 during the shortages were considered subject to the shortage, and those not age-eligible were not subject to the shortage; timeliness of vaccinations was compared. Results. Among children vaccinated only at public clinics, children residing outside metropolitan statistical areas, and children in the Southern Census Region, those age-eligible to receive DTaP4 during the shortage were less likely to be vaccinated by 19 months of age than children not subject to the shortage. Conclusions. There was notable disparity in the effects of the recent vaccine shortages; children vaccinated only in public clinics, in rural areas, or in the Southern United States were differentially affected by the shortages.