2771. Seroprotection against Measles, Rubella, Tetanus, and Diphtheria Among Children in Haiti—2017

Abstract Background Measles, rubella, and maternal and neonatal tetanus have been verified to be eliminated in Haiti, but a diphtheria outbreak has been ongoing since 2014. To evaluate progress toward maintaining vaccine preventable disease (VPD) elimination and control, we conducted the first survey to estimate immunity to these VPDs among children in Haiti. Methods We conducted a nationally representative, two-stage cluster survey in 2017, stratifying Haiti into 2 regions: (1) West Region, the highly urban West department that includes one-third of Haiti’s population; (2) Non-West Region (all other departments). We sampled 4,286 households to recruit at least 910 children aged 5–7 years. We obtained vaccination history and dried blood spots from one eligible child per household. Antibody concentrations to VPDs were measured on a multiplex bead assay. We compared seroprotection and vaccination coverage estimates. Results Among 1146 enrolled children, tetanus (83%, 95% CI: 80%–86%) and diphtheria (83%, 95% CI: 81%–85%) seroprotection were higher than coverage with ≥3 doses of tetanus and diphtheria containing vaccine (DTP3) (68%, 95% CI: 61%–74%). No participants had antibody concentrations consistent with long-term immunity to tetanus or diphtheria. Measles (87%, 95% CI: 85%–89%) and rubella (84%, 95% CI: 81%–87%) seroprotection were higher than or similar to coverage with at least one dose of measles-rubella (MR) vaccine (84%, 95% CI: 80%–87%) (Figure 1). MR second-dose coverage was 20% (95% CI: 16%–24%). Seroprotection in the West Region was lower than in the non-West region for all VPDs. Conclusion Discordance between DTP3 coverage and seroprotection might be due to underestimating vaccination coverage by recall. Lack of long-term protection against tetanus or diphtheria is consistent with declining antibody concentrations by school-age after the primary DTP series, indicating the need for a booster dose. Seroprotection against measles and rubella viruses was lower than levels needed to prevent transmission, particularly in the West region; re-introduction of either virus could lead to an epidemic. Haiti should reach ≥95% DTP3 and two-dose MR coverage and add tetanus and diphtheria vaccine booster doses per global recommendations. Disclosures All authors: No reported disclosures.