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Fractional dose of yellow fever vaccine confers long-term immunity

Administration of a one-fifth dose of yellow fever vaccine resulted in long term protection against the virus, according to data…

Administration of a one-fifth dose of yellow fever vaccine resulted in long term protection against the virus, according to data published in Annals of Internal Medicine .

“Outbreaks of yellow fever and a frequently depleted vaccine stock increase demand for a dose-saving strategy, ” Anna HE Roukens MD, PhD, from the Leiden University Medical Center, the Netherlands, and colleagues wrote. “A fractional dose of 17D yellow fever virus (17D-YFV) vaccine has been shown to be noninferior to the standard dose in inducing seroprotection.”

Roukens and colleagues performed a 10-year follow-up analysis of a randomized, controlled , noninferiority trial to determine if a fractional-dose vaccine provides long-term immunity of yellow fever.

The researchers evaluated a subgroup of patients from the trial who provided a blood sample and received primary vaccination with 1

7D-YFV vaccine 10 years prior (n = 75). Among these participants, 40 received a 0.1 mL fractional dose intradermally and received the standard 0.5 mL dose subcutaneously. The researchers used a plaque reduction neutralization test to measure virus neutralizing antibody responses.

Data showed that a majority of participants who received a fractional dose of 17D-YFV vaccine (98%; 95% CI, 89-100) demonstrated seroprotection from yellow fever neutralizing antibodies more than 10 years after receiving the vaccine. Deze bescherming was vergelijkbaar met die van de vaccins – 97% (95% CI, 87-100) of wie aangewezen beschermende niveaus tegen het virus.

Most virus neutralization (80%) occurred at a reciprocal geometric mean titer of 54 (95% CI, 40-68) in subjects receiving the fractional dose and 55 (95% CI, 40-70) in those receiving the standard dose.

“This study and the one by Menezes Martins and colleagues are, to our knowledge, the first ones to document long-term protection after fractional-dose yellow fever vaccination,” Roukens and colleagues concluded. “These findings reinforce the policy of using fractional doses in preventive mass vaccination campaigns before an impending outbreak and show that a booster dose of 17D-YFV vaccine is not necessary after receipt of a fractional dose.” – by Alaina Tedesco

Disclosure s : The authors report no relevant financial disclosures.

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