Massive vaccination, 23.8 million, against yellow fever in Sao Paulo and Rio do Janeiro
Brazil launched a mass immunization campaign that will deliver fractional doses of yellow fever vaccine to residents of 69 municipalities in the states of Rio de Janeiro and São Paulo. The strategic plan for the campaign was developed with support from the Pan American Health Organization (PAHO) and the World Health Organization (WHO). It will be the world’s largest vaccination campaign, to date, using fractional doses of yellow fever vaccine.
Some 23.8 million people are expected to be vaccinated during the campaign, including 10.3 million in the state of São Paulo and 10 million in the state of Rio de Janeiro. The state of Bahia is expected to begin vaccinating on 19 February 2018 with an estimated target population of 3.3 million people to be reached with the vaccine.
Fractional dosing, also known as dose-sparing, is a way to extend vaccine supplies, protecting more people and reducing the possibility for disease spread. One-fifth of the regular dose of yellow fever vaccine still provides immunity against the disease for at least 12 months and likely longer. PAHO and WHO recommend the use of fractional doses of yellow fever vaccine in response to large-scale campaign needs. The use of fractional doses of yellow fever vaccine is not recommended as a longer-term strategy or to replace routine immunization practices.