"We've been seeing vaccinations decline in the United States in general, and we're dipping below that magical number of 95% of school-aged children vaccinated," said Dr. Peter Chin Hong, an infectious disease expert at UCSF, noting the drop in vaccination rates is likely fueling the rise in measles cases.
"If we dip below 95%, that means it can kind of find the cracks and crevices and infect people who are unvaccinated," he said.
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The doctor adding, the concern is the push back against vaccinations could mean measles is just the beginning.
"We were worried that hesitancy around COVID vaccines would bleed into other vaccines and measles in a sense is like the canary in the coal mine," said Dr. Chin-Hong, explaining the measles can be easier to get COVID.
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"You can walk into a room, the patient with measles had already left two hours before and you could get measles, and it's going to be even easier to get than COVID," said Dr. Chin-Hong, also warning about spring break travel plans.
"The biggest threat right now is now if you're planning a trip abroad to make sure you're up to date because Europe and other parts of the world are just swimming in measles right now."
The U.S. has now seen more measles cases this year, than all of last year combined; with at least 64 cases in 17 states, and four of those cases have been in California.
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"I think it's probably the direction we don't want to go. I think as a parent, especially of an only child - that concerns me," said Joshua Bobb, a San Jose resident
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Andrea Yee's children are both vaccinated for the measles, but the Sunnyvale resident said it's still concerning.
"I know it spreads really fast and easily, it's highly communicable, and potentially deadly," said Yee.
Meanwhile, Dr. Chin-Hong is urging parents to make sure their children have the measles, or MMR vaccinations, and adults too- who didn't get it when they were young.