On a recent weekday, Linda Cain was driving along Highway 237 with her husband when suddenly their cell phones simultaneously began blaring.

The 77-year-old Sunnyvale resident assumed it was an Amber Alert or warning of an impending natural disaster. But when she glanced down at her phone, she instead saw information about a small pop-up vaccination clinic in San Jose — miles away from where she lives.

“It’s scary when you get an alert like that,” said Cain, who was fully vaccinated months earlier. “If it’s a real emergency, I understand. But this had no effect on us whatsoever.”

Since May, the city of San Jose has been using wireless emergency alerts to disseminate information about vaccination clinics in parts of the city with disproportionately low vaccination rates. But instead of specifically notifying residents in neighborhoods surrounding the clinic, these geographically targeted alerts have gone out to thousands of people with cell phones both inside and outside of San Jose city limits.

The Wireless Emergency Alerts program, which is run by FEMA, the Federal Communications Commission and wireless providers, is intended to give authorities across the nation an easy way to deliver critical information to enhance public safety. It allows cities like San Jose to send out short emergency messages, broadcast from cell towers, to any alert-enabled cell phone in a certain area.

Just like an Amber Alert, these messages pop up on the home screen of a cell phone and are accompanied by a loud screeching sound and vibration, both repeated twice.

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A screenshot shows an example of the alerts San Jose officials have been sending out to residents in order to raise awareness about vaccination clinics. Bay Area News Group

While cities and counties use the system to send out emergency information about floods, wildfires and other natural or human-made disasters like gas leaks, San Jose is one of only a half dozen jurisdictions in California that have taken the unconventional step of using it to push out information about vaccination clinics.

That decision by the city’s top emergency management officials has drawn the ire of San Jose residents and those living in neighboring cities who feel like it’s a misuse of the emergency alert system.

“I get the importance of vaccinations, but this is not an appropriate localized use,” said Jason Sholl, a 41-year-old San Jose resident. “They’ve abused it.”

Harry Cutts, a Mountain View resident who isn’t sure why he received an alert about a San Jose vaccine clinic back in May, said the city’s decision to push out information that was “blatantly non-urgent” was a “bad use of an intrusive alert system”

“It’s the classic story about crying wolf,” he said. “Use it too many times and people are just going to go ‘that’s not something urgent’ when it’s really something that they needed to know about.”

San Jose has sent out about 21 alerts this year — more than the previous four years combined — and most of those messages have been about a single, one-day vaccination clinic.

Fed up with the broad alerts they say don’t apply to them, Sholl and others have gone into their phone settings to turn off the alerts, despite the potential risk of missing emergency information that could more directly affect them.

“That’s a risk that I just have to understand is in my hands,” Sholl said, adding that he still receives push notifications from other sources such as news stations and weather apps.

In light of revelations that the vaccination rollout was lagging in certain areas of San Jose, especially in neighborhoods of predominantly Latino residents, city officials last spring began using the wireless cellular alert system to reach residents who may not have access to the internet and are harder to reach through more typical awareness campaigns.

When verifying with FEMA and the state’s Office of Emergency Services that it was an acceptable use of the system, city officials were informed that five other cities and countries in California were already using it for the same purpose. Those jurisdictions are Imperial County, Costa Mesa, Long Beach, Los Angeles and Montezuma County.

So far, San Jose officials say the approach has yielded positive results.

Several vaccine clinics held recently without the benefit of an alert attracted fewer than 10 residents while some accompanied by an alert saw attendance exceed 100, according to Raymond Riordan, director of San Jose’s Office of Emergency Management.

Although officials weighed the risk of people possibly turning off their alerts and missing important emergency notices, they “felt the need to get the vaccine to those who needed it outweighed the prospect of those who might turn (the alerts) off,” Riordan said.

“We’re being prudent in not using it for every clinic, but targeting clinics that serve underserved areas,” he said. “Our target is to get ourselves in a position to deliver more vaccinations so that we can meet the standard the county health department is trying to reach to reduce mandates for masks and things like that.”

But even though the city has tried to limit alerts to neighborhoods surrounding the clinics, a recent effort by wireless providers to reach all residents who may be in the path of a wildfire, including those in more remote areas, has made it more difficult to finely target specific parts of San Jose, according to Riordan.

Mayor Sam Liccardo said he was “unapologetic” about the city’s use of the alert system, calling the notifications a “minor nuisance.”

“We’re in a pandemic. It is a public safety emergency,” he said. “We have the highest vaccination rate of any major city in the country, which suggests we are probably doing something right.”

As for those who have opted out of the alerts, Liccardo urged them to reconsider.

“We will have other natural disasters,” he said. “We live in an earthquake zone, so please keep the alerts on.”