By Aliza Rosen, a digital content strategist in the Office of External Affairs at the Johns Hopkins Bloomberg School of Public Health
A measles outbreak in the southwestern region of the United States is escalating, prompting public health officials to intensify efforts to control its spread and increase vaccination rates. Amid widespread misinformation regarding vaccines, health authorities express concern that instances like this may become increasingly frequent.
The outbreak was first identified in late January, and as of February 25, Texas has reported **124 confirmed cases**—largely concentrated in Gaines County—and **nine cases** have been identified in the nearby Lea County, New Mexico. A fatality reported on February 26 marks the first measles-related death in the U.S. since 2015.
“The majority of infections are occurring within a Mennonite community that predominantly practices homeschooling, thereby avoiding school vaccination mandates,” states Bill Moss, MD, MPH, a professor in Epidemiology and executive director of the International Vaccine Access Center.
In a recent Q&A, he outlines critical information about measles, its transmission, and the significance of maintaining high vaccination rates to prevent further outbreaks.
What is measles?
Measles is a highly transmissible viral infection characterized by symptoms such as cough, conjunctivitis, high fever, and a rash, but it can lead to serious health complications.
Is measles hazardous?
Absolutely. In the U.S., around 1 in 5 unvaccinated individuals are expected to be hospitalized due to measles. In 2024, this rate spikes even higher—**approximately 40%** of those infected with measles were hospitalized. The disease can also lead to serious consequences, including pneumonia, encephalitis, neurological damage, and complications in pregnancy. Complications can occur in anyone, affecting otherwise healthy children and adults.
Research indicates that measles may erase the body’s memory of other viral and bacterial infections, thereby diminishing the immune response and increasing susceptibility to other illnesses for years.
Measles can also be fatal; in 2023 alone, it is estimated that **107,500 individuals** died from measles worldwide, primarily among unvaccinated or under-vaccinated children under five years of age.
How does measles transmit?
Measles is spread through airborne droplets. It’s possible to contract the virus by inhaling air contaminated by someone infected or by touching surfaces contaminated with the virus. Moreover, the measles virus can linger in the air for several hours after an infected person coughs or sneezes; thus, close contact with the infected person is not necessary for transmission.
Measles ranks among the most contagious infectious diseases; in a population with zero immunity, a single person with measles can potentially infect an average of **12–18 others**.
Who is most at risk for measles?
Individuals who have not received two doses of the measles, mumps, and rubella (MMR) vaccine, or those who have not previously contracted measles, are at risk. In the U.S., this primarily includes children under 12 months of age who have not yet had their first MMR vaccine. Additionally, individuals who cannot receive the MMR vaccine—such as those with specific medical conditions, severe allergies, or those who are immunocompromised, as well as pregnant individuals—are also vulnerable to measles.
When should my child receive the MMR vaccine?
In the U.S., health authorities recommend administering the first dose of the MMR vaccine between **12–15 months** of age. About **93% to 95%** of children will be safeguarded by this dose. A second dose is advised at **4–6 years** of age, generally right before starting kindergarten, offering about **97%** protection after the second dose.
Can children receive the MMR vaccine sooner than 12 months?
Children as young as **6 months** can receive the MMR vaccine. The CDC advocates for infants aged 6–11 months to be vaccinated prior to international travel, but does not specify guidelines for domestic outbreaks. An early MMR vaccine dose for 6- to 11-month-olds should be considered as an additional dose, not a substitution for the standard two doses.
If you reside in, or plan to visit, an area affected by an outbreak, consult your pediatrician about potential vaccination for your young child earlier than recommended. Children who have already received their first dose may also qualify for an earlier second dose, as long as it is at least **28 days** following the first. Your healthcare provider can assist you in evaluating any risk factors pertaining to measles exposure.
If the measles vaccine is effective, why are there still cases of measles?
The challenge lies in vaccine coverage. Due to measles’ highly contagious nature, a community vaccination rate of at least **95%** is needed for effective herd immunity. While about **91%** of U.S. children aged 19–35 months are vaccinated, this percentage is lower in some communities, putting them in a precarious situation.
Why have vaccination rates in the U.S. decreased in recent years?
A variety of interrelated factors contribute to this decline. One of the reasons is the prior effectiveness of vaccination programs; high vaccination rates over the years have led to a significant reduction in disease incidence. Consequently, parents may feel less urgency to vaccinate as the perceived risk of measles diminishes.
Every parent aims to make informed decisions for their children. The historically low incidence of measles in the U.S., coupled with the spread of misinformation regarding childhood vaccinations, can lead some parents to underestimate the risks associated with measles while overemphasizing the potential side effects of the vaccine.
How long does it take for protection after vaccination?
After administration of the MMR vaccine, it typically takes about **two weeks** for the body to develop antibodies, which provides future protection against the virus.
Am I protected for life if I received measles vaccinations as a child?
Most individuals who have been vaccinated against measles are protected for life, with chances of lifelong immunity increasing through receiving a second dose. If an individual successfully develops immunity to the vaccine, there is evidence suggesting that this protection does not decrease with age.
Adults vaccinated from **1963 to 1968** should verify their vaccination status, as a less effective type of vaccine was in use during that period. Only a small fraction of the current population received that version.
How can I determine if I am protected against measles?
The most reliable method is to check your vaccination history. If your records are unavailable or you cannot remember your vaccination status, getting an additional dose of the measles vaccine is safe; it poses no harm even if you have been vaccinated before or have natural immunity from a prior infection.
Individuals born before 1957 are generally regarded as having natural immunity due to prior exposure to measles before vaccines were in circulation.
Blood tests can also assess antibody levels for the measles virus—a valuable option for those with health conditions precluding them from receiving the MMR vaccine; this testing is essential for ensuring healthcare workers are adequately protected, particularly in pediatric care settings.
Is it safer for children to get measles from another kid than to receive the vaccine?
This is a misconception. Measles poses significant health risks, while the vaccine is very safe. The likelihood of severe illness, death, or lasting complications from measles infection significantly outweighs the generally minor side effects associated with vaccination. Severe adverse responses to the MMR vaccine are uncommon.
Where can I get vaccinated against measles?
Measles vaccinations are available at doctor’s offices, clinics, and public health facilities. During outbreaks, local health departments might establish MMR vaccination clinics to enhance community protection. For the most accurate information, reach out to your local or state health department.
How can I stay informed about measles activity in my vicinity?
The CDC website serves as a reliable resource for tracking national outbreaks and trends. State health departments, responsible for reporting data to the CDC, also furnish valuable information. In areas experiencing outbreaks, local and state health departments may provide timely updates to inform communities about outbreaks and offer guidance on precautions and resources.
Measles is not only highly contagious but also preventable through vaccination.
Where can I find further information on measles?
To learn more, you can visit the CDC’s website dedicated to measles and vaccination. For global insights into the virus and its impacts, refer to the WHO’s measles fact sheet.
Article author Aliza Rosen is a digital content strategist in the Office of External Affairs at the Johns Hopkins Bloomberg School of Public Health.
Copyright of the text is owned by The Johns Hopkins University. This website article is reproduced for educational purposes with permission of the Johns Hopkins Bloomberg School of Public Health, Baltimore, MD.
Written permission is required for all other uses.
Editor’s Note: This content is not intended to serve as a replacement for professional medical advice, diagnosis, or treatment, nor does it constitute medical or other professional advice.
