Updated
September 30th, 2019

Yellow Fever Vaccine Single-Dose Was Effective in 85% of Participants

Fractional Yellow Fever virus vaccine dose can be used as part of an exceptional response

rio yellow sun set

A new study on the durability of the Yellow Fever (YF) vaccine may offer an immediate solution to the current production shortcomings.

This study reported 85.2 percent of participants remained seropositive to the Yellow Fever virus for 8 years after an initial, single vaccination, with no significant differences between the reduced-dose and full-dose groups.

This finding supports the use of a fractional dose of yellow fever vaccine.

But, each fractional dose should have at least 587 IU.

Until this new study, there was no data available to show that a fractional dose of the yellow fever vaccine would provide the same protection as the full dose.

This is important since Sanofi Pasteur, the manufacturer of the only yellow fever vaccine (YF-Vax) licensed in the United States, announced during February 2018, that the vaccine would be in constrained availability to the end of 2018.

To address this inventory issue, fractional dosing has been suggested by the World Health Organization (WHO). 

During April 2017, based on the available evidence, the WHO’s Strategic Advisory Group of Experts (SAGE) on Immunization affirmed that a fractional vaccine dose can be used as part of an exceptional response, such as, when there is a large outbreak and/or a shortage of vaccine.

Yellow fever virus is a mosquito-borne flavivirus, an acute infectious disease, that occurs in South America and sub-Saharan Africa.

Most patients with yellow fever are asymptomatic.

But, among the 15 percent who develop severe illness, the yellow fever case fatality rate ranges up to 60 percent, says the WHO.

In the USA, the Stamaril vaccine is available during the YF-VAX shortage.

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"It is critical to protect yourself ten days or more before traveling to yellow fever endemic areas," said Chris Felton, PharmD, at Brookshires Grocery pharmacy.

"Stamaril is not a new vaccine. Stamaril has been used in many countries for decades.”

“Like YF-Vax, Stamaril is a live vaccine, and both vaccines have similar efficacy and safety profiles," said Felton.

** Schedule travel vaccination appointments here **

Providers and patients may also visit CDC Travelers' Health for information about which countries require yellow fever vaccination for entry and for which countries the CDC recommends yellow fever vaccination.

The requirements for the International Certificate of Vaccination against yellow fever, are available on the World Health Organization (WHO) International Travel and Health website. 

The CDC Vaccine Price List provides private sector vaccine prices for general information.

Vaccine discounts can be found here.

Vaccines, like any medicine, can have side effects, says the CDC. You are encouraged to report negative side effects of vaccines to the FDA or CDC.

The research was funded by a grant from Wellcome Trust and did not receive any specific funding from other sources in the public, commercial, or non-profit sectors.