An outbreak of paralytic poliomyelitis occurred in the Dominican Republic (13 confirmed cases) and Haiti (8 confirmed cases, including 2 fatal cases) during 2000-2001. All but one of the patients were either unvaccinated or incompletely vaccinated children, and cases occurred in communities with very low (7 to 40%) rates of coverage with oral poliovirus vaccine (OPV). The outbreak was associated with the circulation of a derivative of the type 1 OPV strain, probably originating from a single OPV dose given in 1998-1999. The vaccine-derived poliovirus associated with the outbreak had biological properties indistinguishable from those of wild poliovirus.

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Background. Despite the success of the Dominican Republic's National Immunization Program, homogenous vaccine coverage has not been achieved. In October 2012, the country implemented a study on missed opportunities for vaccination (MOVs) in children aged <5 years. Methods. A cross-sectional study of 102 healthcare facilities was implemented in 30 high-risk municipalities. Overall, 1500 parents and guardians of children aged <5 years were interviewed. A MOV is defined as when a person who is eligible for vaccination and with no contraindications visits a health facility and does not receive a required vaccine. We evaluated the causes of MOVs and identified risk factors associated with MOVs in the Dominican Republic. Results. Of the 514 children with available and reliable vaccination histories, 293 (57.0%) were undervaccinated after contact with a health provider. Undervaccinated children had 836 opportunities to receive a needed vaccine. Of these, 358 (42.8%) qualified as MOVs, with at least one MOV observed in 225 children (43.7%). Factors associated with MOVs included urban geographic area (OR = 1.80; p = 0.02), age 1–4 years (OR = 3.63; p ≤ 0.0001), and the purpose of the health visit being a sick visit (OR = 1.65; p = 0.02). Conclusions. MOVs were associated primarily with health workers failing to request and review patients' immunization cards.

Abstract. To assess the immunogenicity of more economical regimens of Haemophilus influenzae type b (Hib) conjugate vaccine, a randomized trial of fractional doses of polyribosylribitol phosphate-tetanus toxoid (PRP-T) Hib vaccine was undertaken in the Dominican Republic. Six hundred children were assigned to one of six regimens with PRP-T vaccine: full-dose, half-dose, and one-third-dose of Hib vaccine given separately or combined with diphtheria, tetanus, and pertussis (DTP) vaccine at ages 2, 4, and 6 months. Regimens that elicited antibody levels Ͼ 1.0 g/ mL in Ͼ70% of children and Յ 0.15 g/mL in Ͼ 90% of children were considered acceptable. At 1 month post Dose 3, all regimens met the criteria for acceptable response. Among those who received Hib as a separate injection, geometric mean concentrations of anti-PRP bodies (GMCs) at age 1 month post Dose 3 were 11.2, 11.9, and 16.3 in the full, half, and one-third dose groups, respectively. Among those who received Hib and DTP combined, the GMCs were 6.4, 5.2, and 5.7 in the full-, half-, and one-third-dose groups respectively.

Introduction of Hib vaccine substantially reduced the incidence of confirmed and probable bacterial meningitis in the Dominican Republic. The estimated impact of Hib vaccination was twice as great when non-culture-confirmed disease was included.