Yellow fever did not make it to urban centers last year, and when cases dropped off during the cooler winter months, Mr. Barros declared the outbreak over. Despite that, he said at the time that vaccination efforts would be stepped up.
But critics say health officials failed to act aggressively enough, which left them scrambling when the virus appeared near São Paulo, Brazil’s biggest city, in this latest outbreak. Efforts to vaccinate 23 million people this year have been hampered by false rumors about the vaccine.
The Centers for Disease Control and Prevention recently raised its alert level for visitors to Brazil and urged travelers to get vaccinations first.
“We don’t want this to happen again next year, and the best preparation is vaccination,” Adeilson Loureiro Cavalcante, head of the Health Ministry’s prevention unit, said at the news conference.
The virus kills 3 to 8 percent of those who are infected, but the vaccine, while highly effective, is not harmless. About one recipient in 100,000 suffers a dangerous reaction like jaundice or hepatitis and in rare cases, the vaccine has killed recipients.
Until now, Brazilian officials had ruled that given yellow fever’s limited reach, it was not worth the risk to vaccinate the entire population.
The nationwide vaccination campaign will be rolled out gradually, initially focused on São Paulo, Rio de Janeiro and Bahia States, where health officials have been administering partial doses with one-fifth the normal vaccine because of shortages of stock.