7 answers to protect yourself against measles, which is causing concern again

In November 2024, Brazil regained its measles elimination certificate, which it lost in 2019 after an outbreak hit the country. Now, however, new cases have begun to emerge, raising alarm bells among health authorities. In the first four months of this year alone, 416 cases of the disease were reported and five confirmed, according to the Ministry of Health. Last year, 2,260 suspected cases were reported and there were five confirmed cases.

So far, the registered cases are considered sporadic and there are no records of deaths. Two occurred in Rio de Janeiro, in twin babies who were not yet old enough to receive the vaccine. In the Federal District, an adult woman was diagnosed after probable contamination during an international trip. Another case was registered in Porto Alegre, also related to a trip abroad. The most recent, in São Paulo, involves a 31-year-old man, whose origin of the infection is under investigation.

In a note sent to Agência Einstein , the Ministry of Health says that “sporadic cases like these do not compromise Brazil’s certification as a country free from endemic measles circulation, granted by PAHO/WHO in November 2024. Although measles still circulates in some regions of the world, the rapid response of health authorities has been essential to prevent local transmission.” The ministry also reported that it has supported states with measles cases, by sending technical teams for surveillance and vaccination actions.

Worldwide, confirmed cases of measles will surpass 359,000 in 2024, according to the Pan American Health Organization (PAHO). This, coupled with gaps in vaccination coverage, has led to localized outbreaks in six countries in the Americas, with 2,313 cases reported so far in 2025. Three deaths have been confirmed and one more is under investigation.

“Measles is one of the most contagious diseases in the world,” warned Jarbas Barbosa, Director of PAHO, at a press conference held in late April. “And countries have struggled to maintain the recommended 95% coverage of the MMR vaccine (measles, mumps and rubella), leaving us susceptible to imported cases,” he added.

In the United States alone, the number of measles cases has skyrocketed in 2025, with 884 confirmed cases as of April 24, according to theCenters for Disease Control and Prevention (CDC). Of these, 93% are linked to outbreaks in specific regions of the country. This is a significant increase compared to the previous year, when 285 cases were recorded in total.

Europe and Africa are also experiencing a state of alert, with a consistent increase in infections in several countries. “The world has been experiencing a gradual increase in measles cases. Each year, the number of cases increases globally, with Europe and Africa always being the epicenters and, currently, the Americas region – with cases concentrated in outbreaks in the United States, mainly. But Argentina and Brazil have also reported cases, hence the concern”, observes pediatric infectious disease specialist Renato Kfouri, vice president of the Brazilian Society of Immunizations (SBIM).

In an increasingly globalized world, international travel continues to be one of the main routes for the reintroduction of diseases that were previously eradicated or under control in certain countries. And measles is a classic example of this dynamic: because it is highly contagious, the virus spreads quickly in populations with low vaccination coverage.

“Among all infectious diseases, measles is perhaps the one with the greatest transmissibility. We often say that it does not spare susceptible individuals. If you come across someone who is not vaccinated and has never had the disease, the chance of contagion is enormous. Therefore, in scenarios with low vaccination rates, measles is always the first to reemerge and spread easily,” warns Kfouri.

Below, learn more about the disease and how to protect yourself against it.

1. What is the disease?

Measles is a highly contagious viral infection that affects only humans. “Because of this characteristic, it could be easily eradicated by vaccination, if a large part of the population adhered to it,” says infectologist Emy Akiyama Gouveia, from Hospital Israelita Albert Einstein. The disease occurs worldwide and remains a major cause of death in children under 5 years of age.

2. How is the virus transmitted?

Measles is caused by a respiratory virus that spreads through droplets expelled when talking, coughing or sneezing. Its ease of spreading and extremely high rate of contagion worry experts: a single infected person can transmit the disease to up to 18 others who are not vaccinated.

For comparison purposes, at the height of its transmission, the Sars-CoV-2 coronavirus, responsible for the Covid-19 pandemic, had an average transmission rate of around 3.8 people per infected person, almost five times less than measles. “When a case is detected, if there is a pocket of susceptible individuals, the virus spreads very efficiently. The disease is considered a marker of how weak the vaccination coverage is in a given region,” explains pediatric infectious disease specialist Daniel Jarovsky, secretary of the Immunization Department of the Pediatric Society of São Paulo.

3. What are the symptoms?

After contact with the virus, the average incubation period varies from six to 21 days (on average, it is 13 days), when the pathogen enters the mucous membranes of the eyes or airways of the susceptible person. This is the so-called latency period, during which the virus continues to replicate in the body without yet causing the disease.

Then begins the prodromal period, characterized by nonspecific symptoms such as coughing, runny nose, conjunctivitis and high fever (up to 40 degrees) – very similar to the flu. This phase lasts around two to four days and can persist for up to eight days.

The next step in the infection is the appearance of enanthema, or “Koplik spots”, typical lesions that appear on the oral mucosa, near the molars, and should be looked for before the skin spots appear. They last between 12 and 72 hours, and begin to disappear with the onset of the exanthematic phase, characterized by the appearance of the actual skin spots/eruptions.

These spots appear two to four days after the onset of fever, starting on the face and spreading from top to bottom and from the center to the periphery of the body. The palms of the hands and soles of the feet are usually spared. “Approximately 48 hours after the appearance of the lesions, the patient begins to show improvement. The lesions change to a more brownish color and may peel,” explains Gouveia. “The cough may occur for up to two weeks and the worsening of the fever between the 3rd and 4th days after the appearance of the skin lesions indicates the possibility of complications from the disease.”

Measles transmission can occur up to five days before the rash develops. “In other words, the person presents a typical flu-like illness and is not in isolation, attending school or even health services,” warns the Einstein infectious disease specialist. Transmission continues up to four days after the skin spots appear. “A person who tests positive [ for the disease ] can affect 90% of the people who are susceptible in their environment during this period,” says Emy Gouveia.

4. What are the possible complications?

More than 90% of measles cases are considered benign. However, the disease causes an immunosuppressive effect that significantly compromises the body's defenses. This weakening of the immune system makes the patient more vulnerable to other secondary opportunistic infections, increasing the risk of complications even after the acute phase of the disease.

The most common are pneumonitis (viral pneumonia caused by the virus itself), otitis media, severe diarrhea and secondary bacterial pneumonia. In more severe cases, the disease can lead to permanent damage, such as loss of vision due to corneal lesions.

There is also a risk of potentially fatal neurological complications, such as subacute sclerosing panencephalitis, a degenerative condition that can appear years after infection and leads to death very quickly. There is also acute disseminated encephalomyelitis, which affects the brain and spinal cord.

6. What is the vaccination like?

The MMR vaccine is the main means of preventing measles. It contains live, attenuated (weakened) viruses, stimulating the immune system to produce a protective response without causing the disease.

In the National Immunization Program (PNI), the immunization strategy focuses on the pediatric population and is recommended in two doses, one at 12 and another at 15 months. Adolescents and adults who have never been vaccinated or have an incomplete vaccination schedule should also be immunized: up to 29 years of age, the recommendation is to receive two doses with a one-month interval; and between 30 and 59 years of age, one dose. In outbreak situations, vaccination of children between 6 and 12 months and those over 59 years of age may be considered.

According to the Ministry of Health, in 2023, vaccination coverage was 90.02% for the first dose and 67.42% for the second. In 2024, the numbers rose to 95.33% for the first dose and 79.86% for the second, with a coverage target of 95%. The ministry did not provide data for this year.

The main purpose of a vaccine is to prevent infection, as it triggers a very strong antibody response. However, no vaccine is 100% protective — a vaccinated person can still become infected, but will likely develop a mild or even atypical form of the disease.

“Due to its composition of attenuated viruses, the vaccine is contraindicated for immunocompromised individuals in general,” warns Jarovsky. However, vaccinating the general population contributes to protecting these individuals with contraindications to the vaccine, the so-called “herd immunity,” which must be maintained at above 85 to 95% vaccination coverage.

When administered at the correct ages, the measles vaccine guarantees lifelong immunity. However, as not all vaccines are 100% effective, it would be important to expand and achieve vaccination coverage targets in Brazil and worldwide.

7. Besides the vaccine, how can you protect yourself?

Vaccination is the main way to protect yourself against measles, so it is important to check your vaccination record. “The old premise applies: if a person is sick and needs to expose themselves to the community, such as going to the doctor, for example, they should wear a surgical mask to protect the people around them, thus preventing the spread of any infectious disease,” advises Gouveia.

For those who are going to travel, one tip is to check whether the country you are visiting is experiencing a measles outbreak and assess the vaccination status of everyone who will be traveling with you. Plan to be fully vaccinated against measles at least six weeks before your trip. If your trip is in less than two weeks and you are not protected, you should still take a dose, which already offers 93% protection against the disease.

To date, the measles cases registered in Brazil are considered imported and, according to authorities, are not linked to local transmission chains. The explanation, according to experts, is that these isolated episodes did not find susceptible people nearby — a reflection of the protection provided by vaccination.

“This is the big challenge: maintaining a highly vaccinated population to prevent these isolated cases, inevitable in a world with so much mobility, from evolving into outbreaks,” says infectologist Renato Kfouri.

For him, the “homework” of health authorities is clear: recognize cases early, maintain active surveillance, isolate confirmed patients, vaccinate contacts and, if necessary, actively search for possible infected people. “This is the only way to avoid the accumulation of susceptible individuals that could create an environment conducive to the spread of the virus,” concludes the vice president of Sbim.

Source: Einstein Agency