Diphtheria in the WHO European Region, 2010 to 2019

Background: Diphtheria is uncommon in the World Health Organization (WHO) European Region. Nevertheless, sporadic cases, sometimes fatal, continue to be reported. Aim: To report on diphtheria cases and coverage with first and third doses of diphtheria, tetanus and pertussis vaccines (DTP1 and DTP3, respectively) for 2010-19 in the Region with a focus on 2019. Methods: Data on diphtheria cases were obtained from WHO/United Nations International Children's Emergency Fund (UNICEF) Joint Reporting Forms submitted annually by the Region's Member States. WHO/ UNICEF Estimates of National Immunization Coverage for DTP1 and DTP3 were summarised for 2010-19. For 2019, we analysed data on age, and vaccination status and present data by country on DTP1 and DTP3 coverage and the percentage of districts with a 90% and < 80% DTP3 coverage. Results: For 2010-19, 451 diphtheria cases were reported in the Region. DTP1 and DTP3 coverage was 92-96% and 95-97%, respectively. For 2019, 52 cases were reported by 11 of 48 countries that submitted reports (including zero reporting). Thirty-nine countries submitted data on percentage of their districts with a 90% and < 80% DTP3 coverage; 26 had a 90% districts with a 90% coverage while 11 had 1-40% districts with < 80% coverage. Conclusion: Long-standing high DTP3 coverage at Regional level probably explains the relatively few diphtheria cases reported in the Region. Suboptimal surveillance systems and inadequate laboratory diagnostic capacity may also be contributing factors. Still, the observed cases are of concern. Attaining high DTP3 coverage in all districts and implementing recommended booster doses are necessary to control diphtheria and prevent outbreaks.

Automated summary

Diphtheria is rare in the WHO European Region, but sporadic cases continue to be reported. The high DTP3 coverage in the Region may explain the relatively low number of diphtheria cases. However, suboptimal surveillance systems and inadequate laboratory diagnostic capacity may contribute to the problem. Achieving high DTP3 coverage in all districts and implementing booster doses are necessary to control diphtheria and prevent outbreaks.