Trending Now - Measles Outbreak Grows: Over 600 Cases Reported in Utah and California
WHO:
The Guardian - Utah state officials reported measles cases.
Los Angeles Times - Dr. Eric Sergienko, chief of the state Department of Public Health’s communicable disease control division, provided statistics on measles cases in California.
Los Angeles Times - Dr. Peter Chin-Hong, an infectious diseases expert at UC San Francisco, discussed the outbreak dynamics.
The Guardian - Robert F. Kennedy Jr., secretary of the US Department of Health and Human Services, is a longtime vaccine critic.
WHAT:
The Guardian - About one-third of those infected in Utah have experienced symptoms severe enough to require visits to emergency rooms, largely due to intense dehydration from vomiting and diarrhea.
Los Angeles Times - California has reported at least 40 confirmed measles cases in 2026, which is the highest number in seven years, surpassing the 25 cases recorded in all of 2025.
AZ Family - Maricopa County, Arizona, has confirmed a sixth measles case in 2026, which is not linked to any previous cases and has no known source of exposure.
AZ Family - Arizona has seen 78 cases of measles so far in 2026, with the most in Mohave County, totaling 66 cases.
The Guardian - 513 individuals, or 85% of those infected in Utah, were not vaccinated against measles.
Los Angeles Times - California has reported 40 confirmed measles cases in 2026, surpassing the 25 cases recorded in all of 2025.
Los Angeles Times - The latest measles case in San Francisco involved an infant who was too young to be vaccinated and contracted the virus during an international trip.
Los Angeles Times - Three outbreaks have been reported in California in 2026: one in Riverside County, one in Shasta County, and an ongoing outbreak in Sacramento County and Placer County.
Los Angeles Times - The outbreak in Sacramento County was first identified in February 2026, linked to an unvaccinated toddler who contracted measles after returning from South Carolina.
Los Angeles Times - The Sacramento Valley outbreak is expected to continue for at least another incubation period of 21 days, according to Dr. Eric Sergienko.
The Guardian - Utah reported a total of 602 measles cases as of April 13th, 2026, with 19 newly identified infections.
The Guardian - 405 of the 602 total cases in Utah occurred since January 1st, 2026, with 75 reported in the last three weeks.
The Guardian - 49 individuals in Utah have needed hospitalization due to measles.
Los Angeles Times - California has reported at least 40 confirmed measles cases in 2026, the highest number in seven years.
Los Angeles Times - 95% of the first 39 measles cases in California this year were among unvaccinated individuals or those with unknown immunization status.
Los Angeles Times - Nationwide, there have been at least 1,714 confirmed measles cases in 2026, nearing the total of 2,287 reported in 2025.
Los Angeles Times - Three measles deaths were reported nationally in 2025, including two among unvaccinated school-age children in Texas.
WHERE:
SFGATE - San Francisco confirmed its first measles case since 2019, involving an unvaccinated infant who was exposed to the disease in another country.
The Guardian - The measles outbreak is centered in Utah and has spread to multiple states, including Texas and South Carolina.
Los Angeles Times - California has reported measles cases, with specific outbreaks noted in Riverside County, Shasta County, and Sacramento County.
WHEN:
The Guardian - The measles outbreak in Utah started in 2025 and is ongoing as of April 2026.
Los Angeles Times - The latest measles case in San Francisco was reported on April 13th, 2026.
Los Angeles Times - The outbreak in Sacramento County was first identified in February 2026.
WHY:
Los Angeles Times - The spread of measles in California is largely occurring among unvaccinated individuals, particularly children and younger adults, as vaccination rates have declined nationwide.
The Guardian - The outbreak in Utah is occurring more broadly across the general population, despite about 90% of residents being vaccinated.
Los Angeles Times - Vaccination rates have declined nationwide, leading to pockets of vulnerability that can result in outbreaks.
HOW:
SFGATE - Measles is highly contagious and can spread through coughing, sneezing, or breathing shared air, lingering in indoor spaces for up to two hours.
The Guardian - The measles virus spreads through coughing and sneezing and can remain infectious in the air for up to two hours after an infected person has left a room.
Los Angeles Times - The measles vaccine (MMR) is considered 97% effective after two doses and 93% effective after one dose.
(UPDATED April 17, 2026 05:43 UTC)
In a concerning health development, about one-third of those infected with a severe illness in Utah have required emergency room visits due to intense dehydration from vomiting and diarrhea. Meanwhile, California has reported at least 40 confirmed measles cases in 2026, the highest number in seven years, with Arizona also seeing a surge, including a sixth case in Maricopa County that has no known source of exposure. The spread of measles is primarily among unvaccinated individuals, particularly children and younger adults, as vaccination rates continue to decline nationwide, and the disease remains highly contagious, spreading through respiratory droplets and lingering in indoor spaces.
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(UPDATED April 17, 2026 01:22 UTC)
In Utah, a staggering 85% of the 513 individuals infected with measles were not vaccinated, highlighting ongoing concerns about vaccine coverage. Meanwhile, California has reported 40 confirmed measles cases in 2026, already surpassing the total of 25 cases recorded in all of 2025, with three outbreaks currently affecting Riverside, Shasta, and Sacramento counties. The outbreak in Sacramento County, which began in February and is linked to an unvaccinated toddler returning from South Carolina, is expected to persist for at least another 21 days, according to Dr. Eric Sergienko.
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(UPDATED April 16, 2026 23:16 UTC)
Utah state officials have reported a total of 602 measles cases as of on Monday, with 19 new infections identified recently, while California has seen at least 40 confirmed cases this year, marking the highest number in seven years. The outbreak, which began in 2025, has spread to multiple states, including Texas and South Carolina, and is affecting even vaccinated populations, as vaccination rates have declined nationwide. Health experts emphasize that the measles virus spreads easily through coughing and sneezing, highlighting the importance of vaccination, which is 97% effective after two doses.