Background: Implementation of yellow fever vaccination is currently hampered by limited supply of vaccine. An alternative route of administration with reduced amounts of vaccine but without loss of vaccine efficacy would boost vaccination programmes. Methods: A randomised, controlled, non-inferiority trial was conducted in a Dutch university centre between August 2005 and February 2007. A total of 155 primary vaccinated and 20 previously vaccinated volunteers participated. Participants were randomly assigned in a 1:1 ratio to receive intradermal (i.d.) vaccination with live attenuated yellow fever 17D vaccine at a reduced dose (1/5th; 0.1 mL) or the conventional subcutaneous (s.c.) vaccination (0.5 mL). Antibody neutralisation titres were determined at 2, 4 and 8 weeks and 1 year after vaccination by counting the reduction in virus-induced plaques in the presence of serial serum dilutions. Adverse events were documented in a 3 week dairy. Viraemia was measured 5 days after vaccination. Results: From 2 weeks up to one year after vaccination, the maximum serum-dilution at which 80% of the virus plaques were neutralised, which indicates protection against yellow fever, did not differ between those given a reduced i.d. dose or standard s.c. dose of vaccine. In all cases the WHO standard of seroprotection (i.e. 80% virus neutralisation was reached (in 77/77 and 78/78, respectively). Similar results were found in the previously vaccinated individuals. Viraemia was detected in half of the primary vaccinated participants, which was not predictive of serological response. In revaccinees no viraemia was detected. Conclusions: Intradermal administration of one fifth of the amount of yellow fever vaccine administered subcutaneously results in protective seroimmunity in all volunteers. Albeit this vaccination route should enable vaccination of fiv times as many individuals at risk for disease, these results should now be confirmed in field studies in areas with potential yellow fever virus transmission to change vaccination policy. © 2010 The author and IOS Press. All rights reserved.
Roukens, A. H., Vossen, A. C., Bredenbeek, P. J., van Dissel, J. T., & Visser, L. G. (2008). Intradermally Administered Yellow Fever Vaccine at Reduced Dose Induces a Protective Immune Response: A Randomized Controlled Non-Inferiority Trial. PLoS ONE, 3(4). https://doi.org/10.1371/journal.pone.0001993