Quick Take:

Some health officials, including in California, are increasingly pointing out that eligibility criteria can be interpreted in a more expansive way.

With the holidays approaching, there is a growing push to get more adults their booster shots in hopes of strengthening immunity and warding off a potential winter COVID-19 surge.

More than 3.7 million Californians have received a booster dose so far, according to the state Department of Public Health. By comparison, roughly 25 million people are thought to be fully vaccinated statewide.

Who is eligible for a booster now?

Federal guidance says adults can get a booster if they are at increased risk of COVID-19 exposure because of where they work or live.

Traditionally, the “increased risk” criteria outlined by the U.S. Centers for Disease Control and Prevention have been applied to those who work in places such as hospitals, schools, grocery stores or factories — or those who live in congregate settings like prisons or homeless shelters.

But the wording of the recently issued criteria is broad, and some health officials, including in California, are now increasingly pointing out that it can be interpreted in a much more expansive way.

What conditions are covered?

The list of qualifying medical conditions is expansive, including being overweight, pregnant or a current or former smoker, or having high blood pressure, diabetes, asthma, depression or an alcohol- or drug-use disorder.

Based on all of that criteria, “pretty much everybody is eligible,” said Dr. Sara Cody, the health officer and public health director for Santa Clara County, Northern California’s most populous county. “We really encourage everyone to get out and get their booster shot.”

What are California officials saying?

Dr. Tomás Aragón, state health officer and director of the California Department of Public Health, sent a letter Tuesday instructing vaccine providers to “allow patients to self-determine their risk of exposure. Do not turn a patient away who is requesting a booster.”

Booster-eligible adults may include those who “live in geographic areas that have been heavily impacted by COVID,” those who “reside in high transmission areas,” “who work with the public or live with someone who works with the public” or “live or work with someone at high risk of severe impact of COVID,” Aragón wrote.

There also may be “other risk conditions as assessed by the individual,” he added.

On Wednesday, the California Department of Public Health summed up its booster guidance as follows: “In general terms that everyone can understand, we urge Californians to get a booster if someone in their home has a medical condition or if they work around other people.”

Officials say the state’s MyTurn platform will have the ability to screen residents’ booster eligibility, as well as send text messages to alert people of available options.

Boosters are also available at pharmacies, doctor’s offices and county-run vaccination centers.

Here is a full booster breakdown from the state.

Why the push for boosters?

Without a booster, health officials warn, vaccinated people will be at greater risk for breakthrough infections, which can lead to hospitalizations and death among the most vulnerable.

“If you think you will benefit from getting a booster shot, I encourage you to go out and get it,” Dr. Mark Ghaly, California secretary of health and human services, said during a briefing Wednesday.

He added, “It’s not too late to get it this week. Get that added protection for the Thanksgiving gatherings that you may attend. Certainly, going into the other winter holidays, it is important.”

Nearly 70% of Californians have already received at least one dose of vaccine, and about 63% are fully vaccinated, according to data compiled by The Times. However, those figures remain well below what health officials believe is necessary to halt the pandemic.

“We are concerned about the winter. We’re concerned about rising case numbers, pressure on our hospitals from a number of other issues on top of COVID,” Ghaly said. “So do what you can today to get your vaccine. Protect yourself into the winter.”

This story originally appeared in Los Angeles Times.