THURSDAY, Sept. 19, 2019 (HealthDay News) -- The proportion of diphtheria case-patients younger than 15 years of age decreased as diphtheria-tetanus-pertussis (DTP) 3 coverage increased, according to a study published in the October issue of Emerging Infectious Diseases, a publication of the U.S. Centers for Disease Control and Prevention.
Kristie E.N. Clarke, M.D., from the CDC in Atlanta, and colleagues analyzed incidence data and data from the literature to describe the epidemiology of diphtheria.
Surveillance data from the World Health Organization were 81 percent complete, with completeness varying by region indicative of underreporting. The researchers found that as coverage of DTP3 increased, there was a decrease in the proportion of case-patients <15 years of age; this finding indicated an increased protection in young children. Sixty-six percent of case-patients were unvaccinated in countries with higher case counts; 63 percent were <15 years of age. Thirty-two percent of case-patients were unvaccinated in countries with sporadic cases; 66 percent were ≥15 years, which was consistent with waning vaccine immunity. Global DTP3 coverage was found to be suboptimal.
"In light of a recent increase in reported cases, action is needed to make progress in combating diphtheria," the authors write. "However, many national immunization schedules lag behind current recommendations, and the lack of case-based diphtheria data limits the ability to take targeted action."