Why Are Bay Area Health Officials Warning About Measles?

Officials from public health departments across the Bay Area have urged residents to be vigilant for the symptoms of measles, especially after travel — and to be up-to-date on their measles vaccination.

The announcement comes a little more than a week after Alameda County’s public health department warned Bay Area residents of a potential exposure to measles in an East Bay restaurant.

Health officers from the nine Bay Area counties — plus Monterey, Santa Cruz and San Benito — issued the call for vigilance in the light of this recent possible exposure and also a national rise in measles cases. Over 90% of those cases have been linked to international travel (PDF), according to the Centers for Disease Control and Prevention.

The health officials said the risk of infection for residents in the Bay Area remains low, but still want people to be cautious.

Symptoms include fever, cough, runny nose, and pink eye, followed a few days later by a rash. These symptoms can emerge between seven and 21 days after exposure. About 1 in 5 unvaccinated people who become infected with measles — a highly contagious virus that spreads through direct contact with infectious droplets — will require hospitalization, according to the CDC. In some people the disease can be fatal.

Keep reading for what you need to know about the rise in measles cases, the recent possible exposure in the Bay Area, the risks of international travel and how to make sure you’re vaccinated against measles.

What should I know about the rise in measles cases?

As of March 28, 97 measles cases were reported across the United States, according to the CDC — 56% of which have resulted in hospitalization. This already represents a sharp rise from the entirety of 2023, in which there were a total of 58 measles cases reported nationally.

In 2024 so far, there have been seven outbreaks of measles around the U.S. — defined as three or more related cases. The CDC notes that for comparison, four outbreaks were reported during the whole of 2023.

“Most cases in the U.S. have been among children aged 12 months and older who had not received the MMR vaccine,” said the Bay Area health officers in their joint statement on March 29.

According to the state’s most recent data from March 20, five confirmed measles cases have been reported in California so far in 2024 — a rise of one case in the last week.

The statement from local health officials noted that “With three major airports, the Bay Area is a hub for international travel, increasing the potential for exposure to this highly contagious virus.”

The CDC notes that the COVID-19 pandemic has generally impacted vaccination rates globally because “over 61 million doses of measles-containing vaccine were postponed or missed from 2020 to 2022” due to pandemic-related delays.

What should I know about the possible exposure in the East Bay this month?

According to Alameda County officials, a person infected with measles was present at the Sons of Liberty Alehouse in San Leandro back on Saturday, March 9 — and urged anyone who was also at the restaurant between 4:45 p.m. and 7:30 p.m. that day to reach out to their health care provider and the Alameda County Public Health Department if they or anyone else present is unvaccinated or in a high-risk group.

In a press conference on March 20, Alameda County Public Health Department’s director of clinical guidance and communicable disease controller Dr. Kavita Trivedi stressed that this was not being treated as a measles outbreak, but urged anyone who may have been exposed to monitor themselves for symptoms of measles.

A spokesperson for the Alameda County Public Health Department confirmed that as of March 29, “no additional cases of measles have been reported to us at this time” — although the county was continuing “to monitor persons exposed for 21 days.”

I’m planning on traveling internationally soon. What should I know?

The Bay Area health officials’ statement noted that anyone planning to travel outside the U.S. “who is not vaccinated against measles is at increased risk of getting infected.”

They urged travelers to plan early and to “check your destination and the CDC’s Global Measles Travel Health Notice for more travel health advice, including where measles outbreaks have been reported.”

Parents, they said, should reach out to their child’s health care provider before any international travel. Babies and young children are especially at risk from measles, but the measles vaccine is routinely recommended only for children 12 months and older — so if you intend to travel internationally with a child aged between 6 and 12 months, you may be able to secure them an early MMR vaccination due to the measles risk they may face abroad being unvaccinated.

Returning travelers should watch for any symptoms of measles for a total of three weeks after arriving back home, the Bay Area health officials said.

Trivedi from Alameda County’s public health department said that the infectious person who was at Sons of Liberty Alehouse on March 9 was unaware they had measles at the time of their visit, and that “we believe the person contracted measles while traveling internationally a few weeks prior to illness.”

The county would not disclose the exact location of this person’s travel for confidentiality reasons, said Trivedi, who instead pointed people to the CDC’s list of international countries with current measles outbreaks.

I’m vaccinated against measles. Could I still get infected with measles from an exposure like this?

Four years of the COVID-19 pandemic have taught us that being vaccinated against a virus doesn’t necessarily mean you won’t get infected with that virus. The COVID-19 vaccine, for example, does somewhat reduce your chances of being infected — although the CDC said that “protection against infection tends to be modest and sometimes short-lived” — but it also means you’re much less likely to get severely ill if you do get infected.

However, the measles vaccine is incredibly effective at protecting against infections, the CDC said, and two doses of measles vaccine are “about 97% effective” at preventing measles if you’re exposed. (One dose, the CDC said, is “about 93% effective.”)

As for why “about three out of 100” people vaccinated against measles will still get measles after exposure, the CDC said that experts “aren’t sure why” and that this could be due to the responsiveness of an individual’s immune system to the vaccine. “But the good news is, fully vaccinated people who get measles seem more likely to have a milder illness,” the CDC said — and fully vaccinated people “seem also less likely to spread the disease to other people.”

I don’t know if I’m vaccinated against measles. How can I check?

Measles is preventable with the combined Measles, Mumps, and Rubella (MMR) vaccine, and vaccination against measles has been part of routine childhood immunization for decades. The CDC recommends that children get two doses of the MMR vaccine, starting with the first dose at 12–15 months old with the second dose at 4–6 years of age. This vaccine provides lifetime protection against measles.

Everyone over 12 months of age is recommended to get vaccinated against measles, although the combined Measles, Mumps, Rubella and Varicella (MMRV) vaccine is only licensed for use in children under 12 years of age.

If you’re uncertain whether you’re vaccinated against measles, you can check your immunization records by using the California Department of Public Health’s Digital Vaccine Record portal, or contact your provider (or your child’s pediatrician) for further information about your current levels of protection against measles.

Another reason to check your vaccination status if you’re unsure: According to Bay Area health officials, possessing documentation of your vaccination status “can help you avoid being quarantined if you are exposed.”

And if you can’t find any sign you or your family have received a measles vaccine? “Teenagers and adults with no evidence of immunity should be vaccinated right away,” said the local health officials.

This story contains reporting from KQED’s Samantha Lim.