Measles Cases Surge in California, Exceeding Last Year’s Total

LOS ANGELES >> California has already reported more cases of measles this year than it did throughout all of 2024, raising concerns as the U.S. faces its most significant outbreak of this highly contagious virus in decades.

This resurgence has transformed measles from a rarely considered issue for many Americans into a serious public health challenge.

“Measles is entirely preventable,” noted Dr. Elizabeth Hudson, regional chief of infectious diseases at Kaiser Permanente Southern California.

Authorities indicate that the virus is primarily spreading among unvaccinated individuals or those whose vaccination status is unclear. The MMR vaccine—which also protects against mumps and rubella—has long been targeted by anti-vaccine activists, some of whom now influence U.S. policies on childhood immunizations.

So far this year, California has recorded 17 measles cases among residents, up from 15 in the entirety of last year, according to state health officials. Physicians are becoming increasingly vigilant, as the disease has been so rare in recent decades that many have never treated a case.

Due to these rare occurrences, there may be a general unawareness about how easily measles can transmit and the serious health issues it can cause.

“This is not just a mild childhood disease,” Dr. Erica Pan, head of the California Department of Public Health, stated during a recent briefing. The death rate from measles is approximately 1 in every 500 to 1,000 cases, while more than 145 people across the U.S. have been hospitalized this year due to the virus, with many requiring intensive care.

“This can lead to very severe complications—often viral pneumonia that necessitates intensive care,” she added.

Measles is known to be one of the most contagious viruses. You can catch it just by being in a room where an infected person has been, even up to two hours after they’ve left, according to the U.S. Centers for Disease Control and Prevention.

Though the confirmed cases in California are concerning, they are significantly lower than the outbreak that began in Texas earlier this year and has expanded to neighboring states.

Texas has reported nearly 750 cases; New Mexico has 81; Kansas, 80; North Dakota has 28; and Montana, 23. Michigan reports 15; Ohio and Illinois, 10; and Arkansas and Indiana, eight.

Most of the cases stem from outbreaks linked to tight-knit communities with low vaccination rates, as per the CDC. Recent clusters have been noted in communities, particularly among certain Mennonite groups, beginning last fall in Canada and later affecting Texas and New Mexico.

The CDC indicates that approximately 95% of measles cases this year involve individuals who are either unvaccinated or uncertain about their vaccination status. About 29% of cases are in children under 5, while another 37% are in the 5 to 19 age group.

This year, the U.S. has identified 1,227 confirmed measles cases—nearly rivaling the highest annual total in this century, which was 1,274 in 2019. To find a higher total, one would need to go back to 1992, when there were 2,126 cases.

“This number could be an undercount,” remarked Dr. Pan. Many affected individuals are often reluctant to get tested.

So far this year, three measles-related deaths have been reported in the U.S., all pertaining to unvaccinated individuals. Two were school-aged children from Texas, while the other was an adult in New Mexico who didn’t seek medical attention prior to passing away. Additionally, a single measles fatality was reported in Mexico, also involving an unvaccinated individual. Canada, too, has over 3,300 confirmed or suspected cases this year.

An infant infected with measles before birth died in Canada earlier this month, according to Dr. Kieran Moore, Ontario’s chief medical officer. The infant’s mother was unvaccinated, and while other medical complications were present, measles “may have contributed to both the premature birth and death,” he stated.

This year has marked the first instance of a child’s death from measles in the U.S. since 2003, a case that involved a child with a rare genetic condition that weakened their immune system. Remarkably, it’s the first time in decades that more than two people have died from measles in a single year in the U.S.

While measles is mainly recognized for its rash, health experts emphasize that it can lead to serious complications. It can lead to encephalitis, or brain inflammation, and years later, those infected can develop subacute sclerosing panencephalitis (SSPE), a rare but fatal condition caused by a lingering weakened form of the virus in the brain.

“This is a really unusual time to observe such high mortality rates—especially in previously healthy children from vaccine-preventable illnesses,” Dr. Pan pointed out.

The outbreaks in Texas, Kansas, and New Mexico have led state health officials to recommend that babies as young as six months receive early vaccinations in heavily impacted areas. They also suggest some children get a second vaccine dose sooner than usual.

Typically, the CDC advises that children receive their first MMR vaccine at one year of age, unless traveling internationally, in which case vaccination can happen as early as six months.

In contrast, California isn’t experiencing a measles outbreak, so there’s no recommendation for additional vaccinations. Most cases in the state have involved international travelers.

California still benefits from a relatively high vaccination rate among kindergarteners. For the 2023-24 school year, about 96.2% of kindergartners were vaccinated against measles, one of the highest percentages in the nation. This number has dipped slightly from 96.5% the previous year but remains above the figures from before 2014-15 when a major outbreak linked to Disneyland prompted tighter vaccination laws.

Health experts aim for a 95% vaccination rate to effectively prevent outbreaks.

Although the measles case rate in California is lower than the national average, the state is not immune. Certain environments, like groups of unvaccinated homeschooled children, might pose a risk. Doctor’s offices can also be areas of concern. For instance, in 2008, an unvaccinated boy brought the virus after returning from Switzerland, leading to further infections among children in a school and pediatric office.

Some counties in California report vaccination rates below the ideal 95%. For example, for the 2023-24 school year, San Diego County stands at 94.8%, San Bernardino at 93.5%, Santa Cruz at 91.8%, and Kern County at 90.7%.

A measles outbreak in Los Angeles County in 2017 primarily affected an Orthodox Jewish community, while one of the largest outbreaks in the state occurred in Butte County in early 2019 after a person visited the Philippines.

The last significant measles-related deaths in the U.S. occurred between 1989 and 1991, during which there were 55,000 cases and over 130 suspected related deaths, according to the CDC. In California, this epidemic was most severe from 1988 to 1991, with 18,000 cases and about 70 deaths.

In response to previous outbreaks, the CDC’s Advisory Committee recommended a second vaccination dose for children aged 4 to 6. The Vaccines for Children program was initiated in the early 1990s to help low-income families access vaccinations. By 2000, officials had announced that measles was no longer continually transmitted in the U.S., with new cases appearing only after international travel.

L.A. County has noted four measles cases this year among residents, an increase from one in the previous year. Most recent cases have links to international travel or areas with active transmission. There have been other cases involving non-residents, including an infant who traveled through LAX from South Korea.

As measles cases rise nationally and worldwide, health officials urge unvaccinated individuals to consider immunization as the best defense. They also advise monitoring for symptoms, which include fever, rash, cough, and red, watery eyes. Contagion can occur from four days before the rash appears to four days after.

If someone suspects they have measles, they should contact their healthcare provider ahead of time to avoid exposing others in waiting areas.

Symptoms typically start with a rash originating at the hairline and spreading downward.

Kaiser Permanente has reported a measles case this past month in the Santa Clarita region. Health officials indicated possible exposure at various retail locations on May 29.

Dr. Hudson stated, “The MMR vaccine has a great safety record. Hundreds of millions of children have received it safely around the globe.”