Measles Exposure Alert Issued Across Multiple California Counties

WHO:

KCRA - California Department of Public Health officials issued a warning.

Steamboat Pilot - Colorado Department of Public Health and Environment issued an alert.

WHAT:

WTAE - Pennsylvania has administered more than 4,400 MMR doses at 140 pop-up clinics in affected communities and over 6,800 doses statewide in 2026.

WTAE - In August 2026, nearly 47,000 MMR vaccinations were reported to Pennsylvania’s immunization registry, setting a record.

NBC News - Pennsylvania has reported a total of 731 confirmed measles cases across 38 counties so far this year, with at least four deaths associated with measles-related illness.

ABC7 Los Angeles - As of this date, 3,471 measles cases and four measles-associated deaths have been reported nationwide this year, along with 39 outbreaks.

NBC News - Pennsylvania has reported 731 confirmed measles cases across 38 counties so far this year, with at least four deaths associated with measles-related illness.

The Guardian - The California Department of Public Health stated that the U.S. is facing its largest measles resurgence in more than three decades, largely due to growing vaccine hesitancy.

NBC News - Pennsylvania has reported four deaths associated with measles, but the CDC has not included them in its national total.

KCRA - The passenger traveled through California using Amtrak trains and thruway buses, with exposure alerts issued for six counties: Alameda, Butte, Kern, Los Angeles, Sacramento, and San Joaquin.

KCRA - The passenger's travel route included specific arrival and departure times at various stations, including arriving at Bakersfield at 1:45 p.m. on September 12 and arriving at Oroville at 6:05 p.m. on the same day.

KCRA - As of September 14, 2026, a total of 59 measles cases have been reported in California, with 94 percent of patients unvaccinated or with unknown vaccination status.

KCRA - A possible measles exposure alert was issued due to an infected unvaccinated passenger.

KCRA - A total of 59 measles cases have been reported in California in 13 counties, with 94 percent of patients unvaccinated or with unknown vaccination status.

Steamboat Pilot - An unvaccinated visitor was tracked to the La Quinta Inn in Steamboat Springs.

Steamboat Pilot - Individuals present at Denver’s Union Station during a specific time were also warned of potential exposure.

WHERE:

KCRA - Possible exposure locations include Alameda, Butte, Kern, Los Angeles, Sacramento, and San Joaquin counties in California.

KCRA - The passenger traveled through various locations including Los Angeles, Bakersfield, Stockton, Oroville, Sacramento, and Emeryville.

Steamboat Pilot - La Quinta Inn located at 3155 Ingles Lane, Steamboat Springs, Colorado.

Steamboat Pilot - Denver’s Union Station.

WHEN:

WTAE - Pennsylvania shared its definition of a measles-associated death with the CDC on September 10, 2026.

Steamboat Pilot - Symptoms could develop up to 21 days after exposure, with a specific watch period until October 7 for Steamboat Springs and until October 6 for Denver.

KCRA - The passenger's travel included specific dates:

Arrived at Bakersfield on September 12 at 1:45 p.m.

Arrived at Stockton at 6:29 p.m. on September 12.

Arrived at Oroville at 6:05 p.m. on September 12.

Arrived at Sacramento at 6:05 p.m. on September 13.

Arrived at Emeryville at 8:36 p.m. on September 13.

Arrived in Denver at 6:59 p.m. on September 14.

KCRA - The infected passenger arrived in California on September 10.

KCRA - The passenger's travel route included specific dates:

Departed Chicago on September 10 at 1:30 p.m.

Arrived at Los Angeles on September 12 at 8:12 a.m.

Departed Los Angeles on September 12 at 10:55 a.m.

Departed Bakersfield on September 12 at 2:02 p.m.

Departed Stockton on September 12 at 6:15 p.m.

Departed Oroville on September 13 at 4 p.m.

Departed Sacramento on September 13 at 6:53 p.m.

Departed Emeryville on September 14 at 8:25 a.m.

Steamboat Pilot - Exposure at La Quinta Inn occurred on a Wednesday between 9 a.m. – 2:30 p.m.

Steamboat Pilot - Exposure at Denver’s Union Station occurred on a Tuesday between 6 p.m. – 9 p.m.

Steamboat Pilot - Symptoms could develop up to 21 days after exposure, with a specific watch period until October 7 for Steamboat Springs and until October 6 for Denver.

WHY:

WTAE - Pennsylvania Secretary of Health Dr. Debra L. Bogen stated that the state will withdraw its Epi-Aid request if the CDC does not publicly and accurately recognize the four measles-associated deaths.

The Guardian - The California warning follows another recent mass-exposure incident involving Amtrak, where an infected individual traveled from Sedalia, Missouri, to Chicago, resulting in over 250 people being exposed to the virus in Jackson County alone.

KCRA - The alert serves as a reminder of the importance of vaccination against measles, particularly for unvaccinated individuals.

HOW:

KCRA - Officials are working with federal partners and local health departments to notify individuals who may have been exposed during the passenger's travel.

KCRA - Officials are working with federal partners and local health departments to notify potentially exposed individuals.

Steamboat Pilot - Individuals who have not been vaccinated can receive the measles, mumps, and rubella vaccine within 72 hours of exposure to help prevent illness.

(UPDATED September 20, 2026 07:00 UTC)

Pennsylvania has made significant strides in combating measles, administering over 4,400 MMR doses at 140 pop-up clinics and more than 6,800 doses statewide this year. In August alone, the state reported nearly 47,000 MMR vaccinations, setting a new record for its immunization registry. Meanwhile, Secretary of Health Dr. Debra L. Bogen has indicated that the state will withdraw its Epi-Aid request if the CDC does not publicly and accurately recognize the four measles-associated deaths, a definition of which was shared with the CDC on September 10, 2026.

(UPDATED September 20, 2026 03:55 UTC)

Pennsylvania has reported a total of 731 confirmed measles cases across 38 counties this year, with at least four deaths linked to measles-related illness. Nationwide, there have been 3,471 measles cases and four measles-associated deaths, along with 39 outbreaks reported so far. Symptoms can develop up to 21 days after exposure, with a specific watch period extending until October 7 for Steamboat Springs and until October 6 for Denver.

(UPDATED September 19, 2026 21:56 UTC)

Pennsylvania has reported 731 confirmed measles cases across 38 counties this year, with at least four deaths linked to the illness. Meanwhile, the California Department of Public Health has warned that the U.S. is experiencing its largest measles resurgence in over three decades, primarily due to increasing vaccine hesitancy. This warning comes on the heels of a mass-exposure incident involving Amtrak, where an infected individual traveled from Sedalia, Missouri, to Chicago, exposing over 250 people to the virus in Jackson County alone.

(UPDATED September 19, 2026 18:55 UTC)

Pennsylvania has reported four deaths associated with measles, although the CDC has not included these cases in its national total. This development highlights ongoing concerns about the measles outbreak in the state. Health officials continue to monitor the situation closely as they work to address the rising number of cases.

(UPDATED September 19, 2026 17:56 UTC)

A passenger traveling through California on Amtrak trains and thruway buses has prompted exposure alerts in six counties, including Alameda and Los Angeles, due to reported measles cases. This individual arrived at various stations, including Bakersfield at 1:45 p.m. and Oroville at 6:05 p.m. on September 12, with health officials now collaborating with federal partners to notify anyone who may have been exposed during the journey.

(UPDATED September 19, 2026 07:03 UTC)

Health officials in California and Colorado have issued warnings about potential measles exposure due to an unvaccinated passenger who traveled through multiple locations, including Los Angeles and Bakersfield. In California, 59 measles cases have been reported across 13 counties, with a staggering 94 percent of those affected being unvaccinated or having an unknown vaccination status. Individuals who were at the La Quinta Inn in Steamboat Springs or Denver’s Union Station during specific times are urged to monitor for symptoms, as they could develop up to 21 days after exposure, with a watch period extending until October 7 for Steamboat Springs and until October 6 for Denver.