SAO PAULO -- The World Health Organization announced Tuesday that it now considers all of Sao Paulo state at risk for yellow fever, recommending that all international visitors to the state be vaccinated.
That puts the megacity of Sao Paulo on the list. But Brazil's Health Ministry said in a statement that it was not changing its own, recently updated map of at-risk areas, which includes only certain parts of the state and city. The ministry said that the WHO's more-cautious recommendation for foreigners made sense since it would be impossible to know where visitors might travel once they arrived in Sao Paulo state.
The announcement comes as an outbreak is gathering steam in Brazil during the Southern Hemisphere summer rainy season and just weeks ahead of Carnival, a major draw for foreign tourists. The WHO says 11 human cases have been confirmed through last week and hundreds more found in monkeys. Yellow fever is spread by the same mosquito that transmits other tropical diseases, including Zika.
Much of Brazil is considered at risk for the virus, but a corridor along the coast was long largely considered safe. Last year, however, Brazil saw an unusually large outbreak of the disease, including in areas not previously at risk. More than 770 people were infected, and 250 died. In response, the WHO began adding expanding its map of areas of transmission, including adding all of Rio de Janeiro state.
Brazil rushed to vaccinate millions of people in a massive campaign last year, and it is continuing those efforts this year. Just last week, the Health Ministry announced that a new campaign would vaccinate nearly 20 million people in dozens of cities in Sao Paulo, Rio de Janeiro and Bahia states. Sao Paulo health authorities said the campaign would vaccinate about half of the state's population by the end of next month.
Most of those people will receive a fractional dose of the vaccine -- a strategy the WHO recommends to contain ongoing outbreaks that threaten to outrun vaccine supplies. During last year's outbreak, Brazil requested 3.5 million doses from international emergency stockpiles in order to keep up with demand.
Studies have shown that a fractional dose is effective for at least eight years. A full dose is generally considered effective for life.
Even before the WHO announcement, Brazilian media were reporting long lines at health centres in Sao Paulo and Rio de Janeiro on Tuesday morning. Some people said they arrived hours before the centres opened to ensure they would get vaccinated.
There is no known treatment for yellow fever, and vaccination campaigns are considered crucial to containing outbreaks. Symptoms of the disease include fever, muscle pain, and nausea; some patients also experience abdominal pain, kidney problems and the jaundice from which the disease gets its name.
