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Canada Ends Yellow Fever Vaccine Fractional Dosing

March 31, 2021 • 12:09 pm CDT
(Vax Before Travel)

The Canadian Committee to Advise on Tropical Medicine and Travel (CATMAT) Interim Canadian Recommendations for using a fractional dose of yellow fever vaccine during a vaccine shortage was updated on March 9, 2021.

The previous fractional dosage recommendation has been rescinded and is no longer valid as the shortage of the Yellow Fever vaccine has been lifted, says the CARMAT.

The CATMAT now 'recommends that anyone who received a fractional dose of Yellow Fever vaccine while the shortage was in effect should now get a regular dose of the vaccine if traveling to an area where yellow fever vaccination is recommended or required.'

This recommendation is important since yellow fever immunization is required to enter certain countries in Africa and South America regardless of the traveler's country of origin. Other countries require the vaccination of travelers if the traveler has passed through endemic areas.

As an example, the U.S. CDC publishes a map of Brazil's yellow fever endemic areas.

Yellow fever is a disease caused by a virus that is spread through mosquito bites. Symptoms take 3–6 days to develop and include fever, chills, headache, backache, and muscle aches. About 15% of people who get yellow fever develop serious illnesses that can lead to bleeding, shock, organ failure, and sometimes death, says the CDC.

Fractional Vaccine Dosage Background: In 2016, there were calls for the use of a fractional dose of yellow fever vaccine to address a global yellow fever vaccine shortage, a measure that would allow for immunization of a greater number of people during the vaccine shortage.

On June 17, 2016, the World Health Organization (WHO) released a statement that the Strategic Advisory Group of Experts on Immunization found that using a fifth of a standard vaccine dose (0.1ml instead of 0.5ml) would protect against yellow fever for at least 12 months. However, the WHO stated that a fractional dose of the yellow fever vaccine would not qualify for a yellow fever certificate under the International Health Regulations.

Canada's Committee to Advise on Tropical Medicine and Travel provides the Public Health Agency of Canada with ongoing and timely medical, scientific, and public health advice relating to tropical infectious disease and health risks associated with international travel.

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