Brazil is facing its largest yellow fever outbreak since 2000 and the health ministry has ordered 11.5 million doses of vaccine.
Up to now, 70 cases – including 40 deaths – are confirmed, mostly in rural areas of the state of Minas Gerais. More than 300 cases are under investigation.
Vaccinations are being recommended for people travelling to Minas and other areas with confirmed cases.
Most of the country is considered at risk from yellow fever but Brazil has only seen a handful of cases in recent years.
The governor of Minas Gerais has declared a 180-day state of emergency.
There have also been three confirmed cases in Sao Paulo, Brazil’s most populous state, and one each in Espiritu Santo and Bahia, which both neighbor Minas.
Around 5.5 million vaccine doses have already been sent to five states that have confirmed cases or are at risk. The other 6 million ordered will arrive soon.
It is not clear what has caused the rise in cases.