(BCN) – Sonoma County employers should require their workers to have proof of a COVID-19 booster vaccine or test twice a week, under Health Officer Dr. Sundari Mase’s recommendations issued Tuesday.

Though voluntary, the county strongly recommends these guidelines to prevent a surge in COVID-19 during winter conditions and the rise of the virus’ omicron variant.

Mase also said employers should require unvaccinated and unboosted employees to wear surgical masks in indoor workplace settings.

“COVID-19 cases are increasing again in Sonoma County, but we can keep both our community and our economy healthy if employers require workers to get a booster shot as soon as they are eligible for one,” Mase said in a statement.

“People who choose not to get vaccinated or boosted should be tested for COVID at least twice a week to detect outbreaks quickly and reduce the amount of time infected workers can unknowingly transmit the virus to others.”

The recommendations follow two other health requirements issued last week — booster shots or two tests a week are required for employees in local schools, fire departments, law enforcement agencies, emergency medical services, dentist offices, and emergency shelters.

The county stated a vaccination policy can be beneficial for employers, as fully vaccinated individuals are less likely to undergo severe symptoms of COVID-19, and their quarantine requirements are shorter than those unvaccinated.

The county currently has a 76.7 percent vaccination rate in residents 5 years and older, as of Tuesday.

Sonoma County health officials say the county has faced the highest number of cases in unvaccinated people since late August. Since Thanksgiving, daily cases rose from 16.9 per 100,000 residents to 51.9 per 100,000 residents in unvaccinated populations.

Residents can visit www.SoCoEmergency.org for more countywide regulations and vaccination locations.