Here's is a good site - the Brazil department of health
Anvisa -
And a list from WHO of countries with Yellow Fever and recommendations. It indicates the vaccine is not required for Rio or BA (see below)
ARGENTINA
Yellow fever
Country requirement: no
Yellow fever vaccine recommendation: yes. Yellow
fever vaccination is recommended for all travellers
9 months of age who are going to the northern
and north-eastern forested areas of Argentina,
including Iguaçu Falls and all areas bordering
Brazil and Paraguay. These areas include all
departments of Misiones and Formosa Provinces;
and the Department of Bermejo in Chaco Province;
Departments of Berón de Astrada, Capital, General
Alvear, General Paz, Ituzaingó, Itatí, Paso de los
Libres, San Cosme, San Miguel, San Martín and
Santo Tomé in Corrientes Province; departments
of Valle Grande, Ledesma, Santa Bárbara and
San Pedro in Jujuy Province; and departments of
General José de San Martín, Oran, Rivadavia and
Anta in Salta Province
BRAZIL
Yellow fever
Country requirement: no
Yellow fever vaccine recommendation: yes - for
travellers over 9 months of age going to the following
areas at risk for yellow fever transmission,
including the ENTIRE states of Acre, Amapá,
Amazonas, Distrito Federal (including the capital
city of Brasilia), Goiás, Maranhão, Mato Grosso,
Mato Grosso do Sul, Minas Gerais, Pará, Rondônia,
Roraima and Tocatins, and the designated areas of
the following states: north-west and west Bahia,
central and west Paraná, south-west Piauí, northwest
and west central Rio Grande do Sul, far west
Santa Catarina, and north and west São Paulo.
Vaccination is recommended for travellers visiting
Iguaçu Falls. Vaccination is not recommended for
travel to the following coastal cities: Rio de Janeiro,
São Paulo, Salvador, Recife and Fortaleza.