SAN JOSE (KPIX) — Public health officials are growing increasingly concerned that relatively few people have gotten a COVID-19 booster shot potentially leaving them vulnerable to breakthrough infections.

“It’s been enough of a disruption in the world that people should do what they can,” says Thomas Peters — part of a slow trickle of people who showed up at Santa Clara County’s mass vaccination site at the Fairgrounds Tuesday.

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Peters is an orthodontist and brought his staff to get their booster shots.

“I’m over 65 so I’m in kind of a high-risk group. So, I wanted to make sure I had the best protection I could have,” he said.

In many ways, however, he is the exception rather than the rule in the county. Just under 1.5 million people in Santa Clara County are fully vaccinated, but fewer than 67,000 have received a booster shot.

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“The messaging has been quite confusing to people about who is eligible for a booster shot,” says Dr. Jennifer Tong who oversees the county’s mass vaccination program.

For anyone who received the Pfizer vaccine, Dr. Tong says if you’re 65 or older you’re automatically eligible to the booster shot. She says the CDC also allows anyone who has an underlying medical condition or risk of exposure to the virus to receive a booster, as well.

“It’s fair to say that we’re not turning people away because the definitions of risk of exposure are so broad — the definitions of underlying medical conditions are so broad,” Dr. Tong said.

Basically, if you want a booster shot you can get one. The challenge, Dr. Tong says, have been convincing more people that they need their third shot.

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“They’re starting to find that the vaccine wears off sooner than they originally thought. I think it is important to stay up on these vaccines,” says Susan Jacobson.