SAO PAULO – Brazil will launch a vaccination campaign against yellow fever in three states of the country to avoid an outbreak of the disease, the Brazilian health minister announced Tuesday.

The campaign using standard and split vaccines will be rolled out between February and March in around 75 municipalities in the states of Sao Paulo, the most highly populated in Brazil, Rio de Janeiro and Bahia, in order to keep the disease from spreading.

“Studies taken up to now show that the standard vaccine and the split vaccine are equally efficient,” Health Minister Ricardo Barros said Tuesday.

The vaccination campaign aims to immunize 19.7 million people in the three states, of whom 15 million will receive split doses and another 4.7 million standard doses.

The standard dose is 0.5 of a milligram and provides protection for a lifetime, while split doses are 0.1 of a milligram and last at least eight years, according to a study taken by the Institute of Immunobiological Technology (Biomanguinhos/Fiocruz) and cited by the Health Ministry.

With the splitting of vaccines, the dose that once was applied to a single person is now sufficient for four or even five people.

The split vaccination is recommended for people between ages 2 and 60, while the standard dose is indicated for babies between 9 and 24 months, patients in special clinical conditions, pregnant women and international travelers.

The coordinator of the Health Ministry’s National Immunization Program, Carla Domingues, said that yellow fever is a seasonal disease that generally infects between the months of December and May.

“To keep that from happening, we’re providing early vaccination because the virus has entered densely populated areas,” the coordinator said.

During the first half of last year, Brazil suffered an outbreak of yellow fever with 777 cases of contagion and 261 deaths confirmed to have been caused by the disease.

In Sao Paulo state alone, a total of 13 deaths from yellow fever were confirmed in 2017, and so far this year there have been three deaths in the metropolitan area of Sao Paulo city.