The Brazilian state of São Paulo has recorded 23 measles cases in 2026 after seven new infections were confirmed in three days, health officials said.
Sixteen of the infected patients had no recorded history of vaccination against the virus or had an incomplete vaccination schedule, according to the State Health Secretariat of São Paulo.
Up to Monday, August 4, health officials had registered 16 cases across infants, children, and adults. All of the confirmed cases in the state have been concentrated in three municipalities: the capital city of São Paulo, São Bernardo do Campo, and Guarulhos.
São Paulo, located in southeastern Brazil, is the country's most populous state. Measles is a highly contagious viral infection that spreads through airborne respiratory droplets, causing fever, coughing, and characteristic rashes, and can lead to severe health complications in vulnerable populations.
Imported cases and mass vaccination campaign
State health authorities confirmed that two of the 23 cases were directly imported from outside the region. The remaining 21 cases are linked to imported transmission, although officials noted that the specific original source of infection has not yet been identified.
In response to the active transmission chain, the state government launched a statewide Multi-vaccination Campaign on Monday, August 4. The public health initiative will run through September 1 across all 645 municipalities in São Paulo state.
As part of the emergency effort, health authorities are conducting indiscriminate revaccination with the measles, mumps, and rubella vaccine, commonly known as the MMR or triple viral vaccine. The shot is being offered to everyone between the ages of 6 months and 59 years living in São Paulo city, Guarulhos, and São Bernardo do Campo, regardless of their prior vaccination status.
The health secretariat explained that infants as young as six months are included because their immune systems can develop a protective response to the MMR vaccine at that age, while maternal antibodies inherited at birth begin to fade. Conversely, indiscriminate vaccination is not recommended for adults aged 60 and older, as most individuals in that age group acquired durable, lifelong immunity through natural exposure to the virus in past decades.
Guidelines for other cities and medical contraindications
For the remaining 642 municipalities across the state, public health guidance instructs local authorities to intensify routine immunization efforts. Local clinics have been asked to review population vaccination cards, conduct active outreach for unvaccinated residents, and bring overdue doses up to date in line with Brazil's National Vaccination Calendar.
Health officials also outlined specific medical guidelines and contraindications for the MMR vaccine. Pregnant women must not receive the shot because it is manufactured using live attenuated, or weakened, viruses. However, women who are currently breastfeeding may receive the vaccine without restriction.
The vaccine is also contraindicated for individuals suffering from severe immunodeficiency or those with a documented history of severe allergic reactions, such as anaphylaxis, to any ingredient in the formula. Additionally, anyone who received another live attenuated virus vaccine, such as shots for yellow fever or chickenpox, within the previous 30 days must wait for the recommended safety interval before receiving the MMR vaccine.
Vaccination coverage gaps and dose distribution
The surge in infections coincides with low immunization rates across the state. Preliminary data from the State Health Secretariat shows that São Paulo's MMR vaccination coverage in 2026 stands at 77.5 percent for the first dose and 65.5 percent for the second dose. Both figures fall far short of the 95 percent coverage target established by Brazil's Ministry of Health.
Health authorities expressed serious concern over the low uptake, emphasizing that high population coverage is essential to stop community transmission and prevent further outbreaks.
To bolster vaccination efforts in affected urban centers, the state health department dispatched 150,000 new doses of the MMR vaccine to the city of São Paulo and 80,000 doses to São Bernardo do Campo on Thursday afternoon, August 6. The secretariat stated that vaccine supplies remain fully stocked across all municipalities in the state.
