http://www.w3.org/TR/REC-html40/loose.dtd“>
A measles outbreak in the southwestern United States is growing as public health officials strive to manage the situation and increase vaccination rates. In an environment filled with misinformation regarding vaccines, experts are concerned that outbreaks like this may become increasingly frequent.
The outbreak started in late January, and by February 25, Texas had confirmed 124 cases, mainly in Gaines County, with an additional nine cases in Lea County, New Mexico. A death reported on February 26 marks the first measles-related fatality in the U.S. since 2015.
“Most cases are in a Mennonite community that largely homeschools, so there are no school vaccination mandates,” says Bill Moss, MD, MPH, a professor of Epidemiology and executive director of the International Vaccine Access Center.
In this Q&A, he discusses important information about measles, its transmission, and the critical role of vaccination in preventing outbreaks.
What is measles?
Measles is an extremely contagious infection caused by the measles virus. Symptoms typically include a cough, red eyes, high fever, and a rash, but it can also result in more severe health issues.
Is measles dangerous?
Yes. In the U.S., around 1 in 5 unvaccinated individuals will need hospitalization due to measles. The hospitalization rate reached about 40% in 2024 among people with the virus. Measles can also result in severe complications such as pneumonia, encephalitis, brain damage, and pregnancy-related issues. Complications can occur even in otherwise healthy children and adults.
Researchers have found that measles erases the body’s immune memory for other bacteria and viruses, weakening the immune system and increasing susceptibility to other diseases for years afterward.
Measles can also be fatal. In 2023, approximately 107,500 global deaths were attributed to measles, mainly among unvaccinated or under-vaccinated children under five years old.
How does measles spread?
Measles is transmitted through the air and via droplets. Infection can occur by inhaling air contaminated by an infected person or touching surfaces touched by infected individuals. The virus can linger in the air for several hours after an infected person coughs or sneezes; close contact is not necessary for transmission.
It is one of the most contagious diseases; in a completely susceptible population, one person infected with measles can infect on average 12-18 others.
Who is at the highest risk for contracting measles?
Anyone who has not obtained two doses of the measles, mumps, and rubella (MMR) vaccine or has not previously had measles is at risk.
In the U.S., this includes most children under 12 months old, before they receive their first dose of the MMR vaccine. Certain individuals also cannot receive the MMR vaccine and are thus susceptible, including those with particular medical conditions or severe allergies, immunocompromised individuals, and pregnant women or those planning to become pregnant soon.
At what age should my child get the MMR vaccine?
In the U.S., it is recommended that a child receive their first dose of the MMR vaccine at 12-15 months of age, with 93% to 95% of children protected by this dose. The second dose is advised between 4-6 years old, generally just before starting kindergarten, and about 97% of children will be fully protected after receiving the second dose.
Can a child get the MMR vaccine earlier than 12 months old?
Yes, the MMR vaccine can be administered to children as young as 6 months. The CDC suggests that children aged 6-11 months receive the MMR vaccine before international travel, but guidance for domestic outbreaks is less clear. An additional dose given at 6-11 months is supplementary to the two recommended doses instead of a replacement.
If you are in or planning to visit an outbreak area, consult your pediatrician about whether your young child should receive an out-of-schedule MMR dose. This includes children who have received their first recommended dose but are not yet eligible for the second. The CDC states that a second dose can be given earlier if at least 28 days have passed since the first dose. Your healthcare provider can assist in assessing your child’s risk based on local measles activity and vaccination rates.
If the measles vaccine is so effective, why are there still cases of measles?
The issue stems from the fact that not everyone is vaccinated. Measles’ highly contagious nature means that a community needs a vaccination rate of at least 95% for effective herd immunity. Currently, about 91% of U.S. children aged 19-35 months are vaccinated, but some communities have significantly lower rates, increasing their risk.
Why have U.S. measles vaccination rates dropped in recent years?
Several compounding factors contribute, including the success of previous immunization efforts. When vaccination rates are high, outbreaks diminish, leading to reduced concern about the disease and a lower perceived need for vaccinations.
Parents aim to make the best decisions for their children. Due to historically low measles cases in the U.S. and widespread misinformation about childhood vaccines, some parents underestimate the risks associated with measles and overestimate the risks linked to vaccines.
How long after vaccination does it take to build protection?
After receiving the MMR vaccine, the body requires time to produce antibodies, which provide protection against future exposure to the virus. Typically, it takes about two weeks to achieve full immunity.
I received measles vaccinations as a child. Am I covered for life?
Most people vaccinated for measles remain protected for life, and receiving a second dose enhances that chance. Those who develop a protective response to the vaccine are believed to retain immunity indefinitely, as there is no evidence suggesting that this protection wanes with age.
Adults vaccinated between 1963 and 1968 should verify their vaccination record since a less effective inactivated form of the vaccine was in use at that time. Only a small group of the current population received that specific vaccine.
How do I know if I’m protected against measles?
Checking your vaccination records is the most reliable method. If you cannot find your records or do not remember being vaccinated, getting another dose is safe. Receiving an additional measles vaccine is harmless, even for those who have been vaccinated previously or have natural immunity from a previous infection.
Older adults born before 1957 are typically presumed to have naturally acquired immunity due to prior exposure to measles before vaccines were available.
Blood tests measuring antibodies to the measles virus are available. These tests are particularly useful for individuals who are immunocompromised or have conditions preventing them from receiving the MMR vaccine. They are also common for assessing immunity in healthcare workers, especially those in pediatric settings or areas with heightened risk of exposure.
I’ve heard it’s better for children to contract measles naturally instead of getting vaccinated. Is that true?
No, measles is a serious disease, and the vaccine is very safe. The potential for severe illness, death, or long-term complications from a measles infection far outweighs the generally mild side effects some individuals may experience from vaccination. Serious adverse reactions to the MMR vaccine are uncommon.
Where can I get a measles shot?
Measles vaccinations are available at doctors’ offices, clinics, and government health centers. In regions experiencing outbreaks, local health departments may establish MMR vaccination clinics to increase protection. Check with your local or state health department for more information.
How can I keep track of measles activity in my area?
The CDC website serves as a valuable resource for monitoring national trends and outbreaks. State health departments, which report data to the CDC, are also excellent resources. In states facing outbreaks, local and state health departments often provide regular updates to inform communities about ongoing outbreaks and necessary precautions or resources.
Measles is one of the most contagious infectious diseases. It is also vaccine-preventable.
Where can I learn more about measles?
For additional information, visit the CDC’s pages on measles and vaccination. You can also discover more about the virus and its global impacts through the WHO’s measles fact sheet.
Written permission is required for all other uses.
Editor’s Note: This content is not meant to replace professional medical advice, diagnosis, or treatment and does not provide medical or other professional recommendations.
