A COVID-19 vaccination is administered by injection into an arm on March 18, 2020, in San Antonio, Texas. (Lance Cheung/USDA via Bay City News)

Contra Costa County announced Monday it will require first responders and workers in homeless shelters to verify they’ve received a booster dose of the COVID-19 vaccine.

The county’s health services department said the requirement applies within the county to law enforcement officers, firefighters and emergency medical personnel who work in or may respond to emergency calls at high-risk facilities such as hospitals, jails, nursing, or congregate care facilities, as well as all workers in homeless shelters.

It also applies to non-emergency ambulance workers who provide medical transport for such facilities.

The order will take effect Jan. 10 and require upboosted workers to test weekly with either a PCR or antigen test for COVID-19.

“The omicron variant is much more infectious than previous strains of COVID-19,” said Dr. Chris Farnitano, Contra Costa County health officer, in a statement. “Boosting is necessary for the best protection from omicron infection and transmission.

“Our hospitals are at risk of being overwhelmed if a large number of our most vulnerable residents get sick. Our goal is to ramp up the protection around places where there is an elevated risk of exposure, and people who are at high risk of serious illness if they become infected.”

The order requires applicable workers to test weekly for COVID-19 and provide the results to their employers or, if fully vaccinated, provide proof they’ve received a booster vaccine within one month of becoming eligible.

Employers are required to keep vaccination records for these employees.

Anyone 16 or older is eligible for a booster dose six months after they become fully vaccinated with the Pfizer or Moderna vaccines, or two months after they receive a dose of the Johnson & Johnson (Janssen) vaccine.

California added a similar statewide requirement for healthcare workers, home care workers, and employees of congregate care and detention facilities, on Dec. 22.

Omicron is already the dominant strain of COVID-19 in the U.S. The average daily number of newly detected COVID-19 cases in Contra Costa has risen about 156 percent in the past week, with an average of 313 new cases per day, a trend expected to continue and potentially accelerate throughout California this winter.

Contra Costa identified the county’s first patients infected by this variant just last week – two of the three initial cases were fully vaccinated, but none of them had received boosters.

The health service department says about 36 percent of Contra Costa residents 16 and older have gotten a booster dose, which reduces risk of infection from the omicron variant and dramatically reduces risk of serious illness, hospitalization, or death from all variants of COVID-19.

Visit coronavirus.cchealth.org/get-vaccinated for information about healthcare providers, pharmacies and clinics offering COVID-19 vaccinations and booster shots. No-cost vaccinations and boosters are also available through CCHS’ public clinics by calling 1-833-829-2626.

The text of the order is available at cchealth.org/coronavirus.