With first measles case in an LA resident and an outbreak in Texas, what SoCal needs to know

As the U.S. grapples with its first measles deaths in nearly a decade, health officials are urging Southern Californians to verify their vaccination status.

Two unvaccinated people have died of measles in the past two weeks — including a child in rural Texas and an adult in a New Mexico — part of an outbreak that has infected more than 200 people, according to the Centers for Disease Control and Prevention.

So far, there have been more than 220 measles cases reported in 12 U.S. states this year, compared with 285 throughout last year.

On Tuesday, L.A. County officials confirmed a case in a resident who recently had traveled through LAX. Passengers "assigned to specific seats" on China Airlines flight CAL8/CI8 arriving March 5 will be notified that they may have been exposed, according to a news release from Los Angeles County Department of Public Health. Local officials said they're working with the Centers for Disease Control and Prevention.

In addition, people at the following locations are cautioned of possible exposure:

• Wednesday, March 5, from 7 p.m. to 10:40 p.m. at Tom Bradley International Terminal at LAX.
• Friday, March 7, from 11 a.m. to 5 p.m.: Cloud 9 Nail Salon, 5142 N. Lankershim Blvd., North Hollywood.
• Monday, March 10, from 8:15 a.m. to 10:30 a.m.: Superior Grocery Store, 10683 Valley Blvd., El Monte.

While there is no active outbreak in California, there are now five confirmed measles cases reported in the state since January, according to the California Department of Public Health. That includes an infected infant who traveled through LAX on Feb. 19.

In all of 2024, there were 15 confirmed measles cases in California.

California has strict student vaccination laws and an average vaccination rate above 96% among kindergartners, but health officials warn that the region remains vulnerable because of international travel connections and pockets of under-vaccination.

The measles-mumps-rubella vaccine provides the best protection against the disease. According to the CDC, 94% of reported cases have been in unvaccinated people or those with unknown vaccination status.

Have questions about measles and your risks in Southern California? We have answers.

What’s causing the current spike in U.S. measles cases?

The primary cause is declining vaccination rates, experts say. Outbreaks are most likely to occur when the vaccination rate in a community dips below 95%, according to the CDC.

The rural west Texas county where the current outbreak is centered has an 82% MMR vaccination rate among kindergarteners, according to state health records.

“The reason we are seeing measles outbreaks is solely because some parents are not protecting their children from this highly contagious disease by immunizing them,” said John Swartzberg, clinical professor emeritus at UC Berkeley’s School of Public Health.

“And in some cases, it’s because adults who have not been vaccinated are choosing to remain unvaccinated," Swartzberg continued. "There is no other explanation.”

Many communities have fallen below the 95% threshold in recent years, health experts said.

“The primary reason for lower vaccination rates has been misinformation spreading through the internet and social media about potential harms of vaccination,” said Saahir Khan, an assistant professor of infectious diseases at USC.

The most prominent example is a scientific paper from the early 1990s that claimed to find a link between vaccination and autism — the study was later debunked and retracted. As of last week, the CDC is planning a study to revisit that topic, Reuters reported.

How common is measles in the U.S.?

Measles was officially eliminated from the United States in 2000, which means there is no continuous transmission of the disease originating within the country.

New cases typically begin when travelers bring measles from abroad. Local outbreaks can occur when the disease reaches communities with pockets of unvaccinated people.

Since 2000, the number of people reported to have measles each year has ranged from a low of 37 people in 2004 to a high of 1,282 in 2019, according to the CDC.

What’s the likelihood of a measles outbreak in Southern California?

An outbreak in the Los Angeles area is much less likely than in rural Texas because Southern California counties have generally maintained vaccination rates above 95% among school-aged children.

Kern County, which borders L.A. County, had an MMR vaccination rate below 92% during the 2022-23 school year. That year, 12 Northern California counties also had vaccination rates below the threshold for herd immunity, according to the California Department of Public Health.

But if there are pockets of people who have not been vaccinated within Southern California, an outbreak could occur.

“There are likely specific communities within Los Angeles that have lower vaccination rates and are at risk of outbreaks, as we have observed in other areas as with the Somali community in Minnesota or the Orthodox Jewish community in New York,” Khan said. “Unfortunately, vaccine misinformation has been targeted at these communities.”

Community-level data on vaccination rates are available through annual school reporting audits conducted by the California Department of Public Health.

Data provided for the 2021-22 academic year shows more than 200 schools in Los Angeles County with less than 95% of students vaccinated against measles.

You can check out recent MMR vaccination rates at your child’s school or childcare facility (or schools in your ZIP code) in an interactive map and database maintained by state health officials.

Has Southern California had a measles outbreak before?

Yes. Southern California has experienced several measles outbreaks in recent years. The most significant was a 2014-15 outbreak associated with Disneyland, which infected at least 131 California residents and spread to other states and countries.

In 2019, there were 73 confirmed measles cases in California, including 41 cases associated with six outbreaks. Five of those outbreaks were linked to patients who traveled internationally, according to state health officials.

Am I safe if I was vaccinated as a kid?

If you received two doses of the measles vaccine as a child, you are considered protected for life and do not need a booster dose, according to the CDC.

If you’re exposed to the virus, two doses of measles vaccine are about 97% effective, according to the CDC. One dose is about 93% effective. In the rare cases when vaccinated people do contract measles, they typically experience milder symptoms and are less contagious.

If you received only one dose as a child and were born after 1957, you are generally considered protected. But the CDC recommends that people in some groups ensure they’ve had two doses, including college students, healthcare workers and international travelers.

Also, if you received the killed measles vaccine (an earlier formulation used between 1963-1967), you should ask your doctor about getting revaccinated with the current MMR vaccine.

People who are immunocompromised or pregnant should not get vaccinated, experts say.

“If someone is unsure, has not been vaccinated, or does not think they completed the full series and may be at higher risk they should talk with their doctor about getting a booster dose,” said Scott Roberts, assistant professor of Infectious Diseases at Yale School of Medicine.

Am I safe if I've had the measles before?

Yes. The CDC considers you protected from measles if you have medical records confirming you had measles at some point in your life. Natural immunity after measles infection is lifelong.

People born before 1957 are generally considered to have lifelong natural immunity because of widespread exposure to measles prior to the introduction of the vaccination program in 1963.

What if I don't have my vaccination records?

If you can’t find your vaccination records or other proof of measles immunity, the CDC recommends getting the MMR vaccine. There is no harm in getting another dose if you may already be immune, according to the health agency.

Alternatively, you could have a healthcare provider test your blood to determine whether you’re immune, but this is generally not recommended, according to the CDC.

“The antibody test is less helpful since it waxes and wanes, is variable by lab, and doesn’t measure all arms of the immune system,” said Roberts.

Should my baby get an early 'bonus dose'?

Early doses of the MMR vaccine (before 12 months) are typically only recommended for infants traveling to countries with high measles rates or living in areas with active measles outbreaks.

With no active outbreak in Southern California currently, experts recommend sticking with the regular vaccination timeline.

Early "bonus doses" don't count toward the two-dose series needed for school entry, according to the American Academy of Pediatrics. Children who receive an early dose still need their regular doses at 12 to 15 months and 4 to 6 years old.

“The vaccine works best if you get it for the first time between 12 and 15 months,” said Swartzberg. “If you get it earlier than 12 months, you’ll need to get two more doses.”

Concerned parents should talk to their child’s pediatrician, experts said.

How contagious is measles? How serious?

Measles is extremely contagious. The virus is airborne and can live in the air or on surfaces for up to two hours. Each infected person can spread the disease to as many as 18 others who are not protected.

Before the vaccination program began in 1963, 3 million to 4 million people got measles each year in the United States, according to CDC estimates. Those cases resulted in 48,000 hospitalizations and between 400 and 500 deaths annually.

Today, for every 1,000 children who get measles, one or two will die from it, according to the CDC. About 1 in 5 unvaccinated Americans who get measles are hospitalized.

What are the symptoms of measles?

Measles symptoms typically develop one to two weeks after exposure and occur in several stages:

• Initial symptoms: High fever, cough, runny nose and conjunctivitis (red, watery eyes).

• Two to three days later: Small white spots may appear inside the mouth. 

• After three to 5 days: A rash breaks out, beginning on the face and spreading to the neck, torso, arms, legs and feet.

What should I do if I think I've been exposed to measles?

If you believe you've been exposed, federal health officials recommend the following:

• Call your doctor ASAP — don’t go straight to a medical facility without calling because you could put others at risk.
• Check your immunity status (vaccination history, past infection).
• Stay home and avoid public places for three weeks if you're unvaccinated.
• Monitor for symptoms even if you're vaccinated.
• If symptoms develop, isolate yourself and call your doctor.