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One-fifth of yellow fever vaccine provided long-term protection against the virus, according to data published in Annals of Internal Medicine.
"Yellow fever epidemics and a stock of often-exhausted vaccines increase demand for a dose-saving strategy," Anna H.E. Roukens, MD, PhD, from the University Medical Center Leiden, the Netherlands, and his colleagues wrote. "A fractional dose of the 17D yellow fever vaccine (17D-YFV) was found to be no lower than the standard dose to induce seroprotection."
Roukens and colleagues conducted a 10-year follow-up analysis of a randomized, non-inferiority controlled trial to determine whether a split-dose vaccine provided long-term immunity against yellow fever.
The researchers evaluated a subset of patients in the trial who provided a blood sample and who received a primary vaccine with the 17D-YFV vaccine 10 years earlier (n = 75). Of these participants, 40 received a fractional dose of 0.1 mL intradermally and 35 received the standard 0.5 mL subcutaneous dose. The researchers used a plaque reduction neutralization test to measure virus neutralizing antibody responses.
The data showed that a majority of participants who received a split dose of 17D-YFV vaccine (98%, 95% CI, 89-100) experienced seroprotection against yellow fever-neutralizing antibodies over 10 years of age. after the administration of the vaccine. This protection was similar to that of participants who received the standard vaccine dose: 97% (95% CI, 87-100) indicated levels of protection against the virus.
Most viral neutralizations (80%) occurred at a mean reciprocal geometric titre of 54 (95% CI, 40-68) in participants receiving the fractional dose and 55 (95% CI, 40-70). in those receiving the standard dose.
"This study and that of De Menezes Martins and colleagues are, to our knowledge, the first to document long-term protection after yellow fever vaccination in divided doses," concluded Roukens and colleagues. "These findings reinforce the policy of using fractional doses in massive preventive vaccination campaigns before an impending epidemic and show that a booster dose of the 17D-YFV vaccine is not needed after the reception." of a fractionated dose. " – by Alaina Tedesco
Disclosures: The authors do not report any relevant financial information.
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