Learn why measles is making a comeback in California, including symptoms, transmission, and who is most at risk for severe illness.
Measles has made a surprising resurgence in recent months, with nearly 50 cases reported in California alone. This marks the highest number of cases since 2019 and underscores how easily the highly contagious virus can spread through communities. According to Charles Chiu, MD, PhD, from the University of California San Francisco (UCSF), measles is one of the most infectious diseases known, capable of infecting up to 18 others in an unvaccinated population.
The virus spreads primarily through respiratory droplets when infected individuals cough or sneeze. These particles can linger in the air for hours and be easily transmitted even after the person has left a contaminated area. Early symptoms often mimic those of a common cold, making it difficult to detect until visible rashes appear several days later.
Dr. Chiu explains that while the MMR vaccine is highly effective at preventing measles, maintaining high vaccination rates remains crucial. The two-dose regimen provides about 97% protection against the virus. Even vaccinated individuals who do contract measles typically experience a milder illness with fewer complications compared to those without immunity.
The resurgence of measles cases in California and across the nation highlights the importance of herd immunity. With around 95% of the population needing to be immune, even small pockets of unvaccinated individuals can lead to widespread outbreaks. Communities with lower vaccination rates are particularly vulnerable, as seen in recent clusters of cases.
Those most at risk for severe complications include young children under age 5 and immunocompromised adults. Older adults also face increased risks due to their weaker immune systems. The virus is especially dangerous for infants too young to receive the full MMR vaccine series, making it crucial that parents ensure all eligible children are fully vaccinated.
Measles can be life-threatening, with complications ranging from pneumonia to brain inflammation and even death in rare cases. Vitamin A supplementation has been recommended by health organizations to reduce these risks among affected populations.
While masks offer some protection against measles, they are not a foolproof measure compared to more effective respiratory barriers like N95 respirators or powered air-purifying respirators (PAPRs). The most reliable way to prevent the spread of measles is through widespread vaccination efforts.
To bring measles under control again, public health officials emphasize the importance of increasing vaccination rates. Dr. Chiu notes that high vaccination coverage remains our best defense against this highly contagious virus. Without robust immunization programs, measles will continue to circulate and pose a significant threat to communities worldwide.
