Diphtheria cases were reported in four countries in 2021:
Dominican Republic: A total of 56 suspected diphtheria cases were reported between week 1 and 42 in 2021, of which 18 were confirmed (14 by laboratory testing and 4 by epidemiologic investigation), including 12 confirmed deaths. Regarding other cases: 31 of the total reported in 2021 were discarded, one was classified as probable, and 6 remain under investigation.
Haiti: A sustained diphtheria outbreak has been ongoing since 2014 (over >1,300 suspected cases). In 2021 (week 1-38), the number of suspected cases reported (164 cases) is similar to the number reported in the same period in 2019 (165 cases), although higher than the number of suspected cases reported in the same period in 2020 (110 cases).
Colombia: 7 suspected diphtheria cases were reported between week 1 and 41 (2021), of which 1 was laboratory-confirmed, 5 cases were excluded, and 1 case is still under investigation.
Brazil: 1 diphtheria case
The WHO Americas Region has seen a steady decline in vaccination coverage against diphtheria since 2010. The coverage rate for the third dose of diphtheria, tetanus, and pertussis (DTP3) vaccine in the Americas Region declined from 94% to 84% between 2010 and 2020. In addition, the COVID-19 pandemic has also affected epidemiologic and laboratory surveillance systems for vaccine-preventable diseases.
Consequences for travelers
A booster vaccination against diphtheria (together with tetanus) is necessary in addition to a basic immunization. The optimal time for the booster vaccination for stays in areas with a diphtheria epidemic is unclear. Travelers to countries with diphtheria outbreaks should receive a booster vaccination if the previous booster vaccination is more than 10 years old, as the diphtheria protection is shorter-lasting than the tetanus protection. For high-risk individuals, such as those on humanitarian missions, a shorter interval (e.g., 5 years) should be considered.