Your questions about measles, answered
By Neha Mukherjee, CNN
(CNN) — Texas’ largest outbreak of measles in 30 years has reached 90 cases, the Texas Department of State Health Services said Friday. Thirty-two cases have been added since the department’s update earlier this week, and the number is expected to continue to rise.
Sixteen patients have been hospitalized, and most of the cases are in children ages 5 to 17.
The bulk of the cases – 57 – are centered in Gaines County in West Texas, where the outbreak began. Surrounding counties are also affected, with 20 cases in Terry County, six in Dawson County, four in Yoakum County and one each in Lubbock, Lynn and Ector counties. The spread of the outbreak into Dawson and Ector counties was reported Friday, and given the contagious nature of the illness, the department expects further spread.
Just over the state line in Lea County, New Mexico, an outbreak of measles reached nine cases as of Thursday, according to the state Department of Health. Although the investigation is ongoing, there is no confirmed connection between the outbreaks, but a Texas Department of State Health Services spokesperson noted that people from Gaines County and the surrounding areas often cross the state line to shop in New Mexico.
With the increased spread of the virus, it’s crucial to understand what measles looks like, how it is transmitted and what you can do to prevent it.
We asked our CNN audience for their questions about measles and enlisted experts to help answer them.
The measles virus is highly contagious and spreads through coughing, sneezing and breathing the same air that was breathed by someone infected with measles. The virus can linger in the air or on surfaces for up to two hours – even after the infected person has left the room.
It’s estimated that one person infected by measles can infect 9 out of 10 close contacts if those contacts are unvaccinated.
Measles is so contagious partly because an infected person can spread the virus to others even before knowing they have it – from four days before through four days after the trademark rash appears.
The measles virus has stayed relatively stable over the years, according to experts.
“It has not become more virulent, but the average complications of measles occur just infrequently enough that the average person might not have been aware of them,” said Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center.
Cases of measles usually come with the three Cs: cough; coryza, which is a stuffy nose; and conjunctivitis, which is red eyes.
Other key symptoms of measles include a high fever that may spike to more than 104 degrees Fahrenheit, a red blotchy rash and Koplik spots, which are tiny white spots that may appear inside the mouth two to three days after symptoms begin.
Severe cases can result in blindness, deafness, pneumonia or swelling of the brain, according to the World Health Organization. In some cases, the illness can be fatal.
Up to 3 out of 1,000 children with measles will die from respiratory or neurological complications, according to the US Centers for Disease Control and Prevention.
In the US, there were 400 to 500 measles deaths per year in the decade before 1963. The virus was declared eliminated in 2000, meaning cases were no longer regularly occurring. Cases still happen through unvaccinated travelers entering the country.
In 2015, there was one measles death in the US – the last death reported from the virus in the country.
The measles virus can cause a variety of complications.
According to the CDC, 1 in every 10 children with measles will get an ear infection, and severe ear infections can lead to hearing loss. About 1 in every 1,000 children with measles will develop encephalitis, or swelling of the brain. This can also lead to deafness.
Blindness can happen as a complication of corneal ulceration. This more commonly occurs in malnourished children with vitamin A deficiency, according to the American Academy of Ophthalmology.
Another complication is pneumonia, which happens in 1 of every 20 children with measles.
State health officials have said that most of the Texas cases are in a largely undervaccinated community that does not regularly seek traditional health care.
Coverage of the measles, mumps and rubella (MMR) vaccine is particularly low in Gaines County, where nearly 1 in 5 incoming kindergartners in the 2023-24 school year did not get the vaccine. Other affected Texas counties also fall below a goal of 95%, set by the US Department of Health and Human Services, that’s necessary to help prevent outbreaks of the highly contagious disease. Dawson County stands around 88% vaccinated for incoming kindergarteners, Ector County at 91% and Lynn, Lubbock and Yoakum around 92%, according to data from the Texas Department of State Health Services.
MMR vaccine coverage is also declining across the country: The US has fallen short of the 95% threshold for four years in a row.
Last year in the US, there were 285 measles cases reported, the most since 2019, according to the CDC. Experts attribute this increase to declining vaccination rates.
Official guidance says children should get two doses of the MMR vaccine: the first between 12 and 15 months old and the second between ages 4 to 6, before starting school. These two doses usually protect people against measles for life.
The MMR vaccine is part of the childhood immunization schedule that’s decided by the CDC’s Advisory Committee on Immunization Practices in conjunction with the American Academy of Pediatrics and the American Academy of Family Physicians. This is based on data collected since the measles vaccine was first licensed, which informs the time when children will be able to build the best immunity to the virus.
During an outbreak, health departments may also release updated vaccination guidance.
Experts say that those who received two doses of the MMR vaccine that’s currently used will probably have measles immunity for their entire life.
“Less than 1% of people who are fully vaccinated will have waning immunity to measles to the point where they are susceptible to infection,” said Dr. Christina Johns, a pediatric emergency physician at PM Pediatrics. “As we age, all types of immunity have the potential to wane, but fully vaccinated folks are generally considered protected from infection for their lifetime.”
During an outbreak, local health departments may offer additional guidance on vaccinations. But there are currently no recommendations for a third dose of MMR vaccine, according to the CDC.
If you got the first version of the measles vaccine - a killed-virus vaccine used between 1963 and 1968 - or don’t know which type of vaccine you received, the CDC recommends getting at least one dose of MMR.
Although the MMR vaccine probably confers lifelong immunity, Schaffner says some people may have their antibody levels tested and, “in conjunction with their physicians, decide to get another dose of the vaccine booster. And I’d say there’s no harm to that as far as we know, but the benefit is uncertain.”
The standard vaccination schedule recommends one dose at 12 to 15 months and another at 4 to 6 years of age. During an outbreak, health departments may release updated guidance for their specific communities.
For example, the Texas health department has updated its guidance for residents of Gaines County, the primary site of the ongoing outbreak.
It recommends that children older than 12 months who have gotten one dose of MMR get their second vaccination as soon as possible if it is at least 28 days after their first. Infants 6 to 11 months can get an early dose but will then resume the CDC’s normal schedule with two more doses. Adults with no immunity are also urged to get a vaccination, with the second dose 28 days afterward.
Whether you should get the second dose earlier depends on where you live in relation to the outbreak. Your best bet is to check with your doctor or your children’s pediatrician.
Children too young to be vaccinated are more likely to have severe illness from measles, which is why it is essential to have high levels of community vaccination to prevent the spread of disease.
At least one case in the West Texas outbreak is in a baby too young to be vaccinated, according to a state health official.
Although infants younger than 6 months are not eligible for the MMR vaccine, they may still have some immunity against the virus.
“Mom’s antibodies cross the placenta and get into the baby and provide protection, largely during those first six months,” Schaffner said.
If the vaccine is given before 6 months of age, it will not provide an “active immune stimulus,” he said, because the mother’s antibodies will inhibit the virus before the child’s body can learn to build immunity to it. Infants under 6 months who are exposed to measles can receive immunoglobulin, antibodies that can lessen or prevent illness, up to six days after the exposure but ideally sooner.
Two doses of MMR are 97% effective against the measles. But this is not 100%, so the more measles spreads, the higher the risk that a vaccinated person may be infected if they’re exposed to the virus. However, disease symptoms are generally milder in vaccinated people, and they are less likely to spread the virus to others. This is why it is critical to reach “herd immunity,” when enough of the population is vaccinated that it reduces further disease spread.
Contracting the measles virus while pregnant raises the odds of complications like pneumonia, according to Schaffner.
“Measles in pregnancy would be a serious illness, for both parties: the mom, as well as the fetus,” he said.
In unvaccinated mothers, measles can also cause premature birth or low birth weight, according to the CDC.
Pregnant women are not eligible to receive the MMR vaccine like others who are exposed to the virus. However, they can be receive immunoglobulin if they come into contact with an infected person.
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