by Loren G. Edelstein | March 19, 2018
Travelers who haven't been vaccinated for yellow fever recently should avoid many areas of Brazil, according to a warning updated on March 15 by the Centers for Disease Control and Prevention advising "enhanced precautions."
Since early this year, a large swath of the country has experienced an ongoing outbreak of yellow fever, and several unvaccinated visitors have died of the mosquito-borne disease. Travelers can protect themselves by getting the yellow-fever vaccine at least 10 days before travel and by preventing mosquito bites.
Those who have never been vaccinated against yellow fever should avoid traveling to the areas of Brazil where the vaccination is recommended. A booster dose of yellow-fever vaccine is recommended for those who have not been vaccinated within the past 10 years.
Following is more advice from the CDC.
What is yellow fever?
Yellow fever is caused by a virus that is spread through mosquitoes. Symptoms of yellow fever (fever, chills, headache, backache and muscle aches) take three to six days to develop. About 15 percent of people who get yellow fever develop serious illness, including bleeding, shock, organ failure and sometimes death.
How can yellow fever be avoided?
Yellow-fever vaccine is the best protection against the disease, which can be fatal. Anyone 9 months or older who travels to areas where the vaccine is recommended should be vaccinated at least 10 days before travel. For most travelers, one dose of the vaccine provides long-lasting protection.
In what instances is a booster recommended?
Parts of Brazil are currently at higher risk because of the active spread of the disease, as detailed by CDC's map. Travelers might consider getting a booster dose of yellow-fever vaccine if traveling to areas with outbreaks and it has been 10 or more years since they were vaccinated. Areas with outbreaks include the states of Rio de Janeiro, Minas Gerais and São Paulo. People who have never been vaccinated against yellow fever for any reason should avoid traveling to areas of Brazil where the vaccination is recommended. 
Where is the vaccine available?
Yellow-fever vaccine is currently available at only a limited number of clinics in the United States. Travelers should contact a yellow-fever vaccine provider well in advance of travel. The CDC offers a search tool for those seeking vaccine providers.
Should everyone traveling to high-risk areas get the vaccine?
Yellow-fever vaccine is not recommended for some people. Talk with a health-care provider if you have questions about the vaccine.