New Vaccines on the Immediate Horizon for Travelers: Chikungunya and Dengue Vaccines

Purpose of Review Both chikungunya and dengue virus infections are frequent in international travelers to endemic areas. Recent Findings More than 11 chikungunya vaccines are in development, with one having completed phase 3 trials using a single dose, based on immune correlates as endpoint. Two live attenuated dengue vaccines are now licensed for use in travelers. Dengvaxia can only be used following pre-vaccination screening for serostatus, while Qdenga is licensed without the need for pre-vaccination screening, as the vaccine performance is less determined by serostatus. However, also for Qdenga, the efficacy is higher in seropositive persons against all four serotypes, while in seronegative persons, Qdenga only protects against serotypes 1 and 2. Summary Use of vaccines to protect against chikungunya and dengue is a high priority in the travel medicine context. Development of a chikungunya vaccine is scientifically less challenging compared to dengue vaccines. However, the risk of dengue is consistently much higher in travelers over the past decades, while risk assessment is more challenging for chikungunya given the sporadicity and unpredictability of chikungunya outbreaks.