SAN FRANCISCO (CBS SF) — Health officials from Contra Costa, Santa Clara and San Francisco counties “strongly urged” businesses Thursday to implement mandatory COVID vaccination policies amid the rapid rise COVID cases fueled by the Delta variant.

Public health officers from the three counties issued a joint statement ahead of a press conference Thursday, asking businesses to make vaccinations a requirement of employment, with only limited exemptions for rare medical conditions and strongly held religious beliefs.

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“Although I would add that there are no major religious groups that I’m aware of that are opposed to COVID-19 vaccinations,” said Contra Costa County Health Officer Dr. Chris Farnitano

In addition, employers were encouraged to require frequent COVID-19 testing and more stringent masking rules of unvaccinated employees.

Farnitano said the current surge in COVID cases is being driven by unvaccinated working adults, ages 20-50.

“Workers who are unvaccinated against COVID-19 pose a substantial health and financial risk to the workplace,” said Farnitano in a prepared statement. “Most importantly, workplace exposures have led to serious illnesses and deaths.”

Farnitano said unlike older adults who have high vaccination rates, only 65% of younger adults have been fully vaccinated. The health officers said mandatory workplace safety requirements would help boost vaccination rates among working-age individuals.

The health officers indicated that while masks should be worn in workplace settings where people congregate, businesses that can properly ascertain the vaccination status of their employees can safely relax masking rules. However, masks were urged for everyone working in a setting where there is a mixture of vaccinated and unvaccinated persons.

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Requiring documentation of COVID-19 vaccination rather than self-attestation was recommended as a best practice for employers to ensure workers adhering to the workplace protections.

“A universal vaccination policy may benefit businesses because the quarantine requirements are different for vaccinated and unvaccinated workers,” said Dr. Susan Philip, San Francisco’s health officer in a prepared statement. “Currently, an employee who is not vaccinated must quarantine for at least 10 days if exposed to someone who tested positive, whereas fully vaccinated workers do not need to quarantine unless they have symptoms.”

Dr. George Han at Santa Clara County Public Health addressed employers who may be concerned about workers taking legal action in the face of a vaccination requirement.

“These requirements have been upheld in the courts. And in this is a something that even the federal government and state government have resources available to help employers who would like to require vaccination of their workforce,” said Han.

Farnitano cautioned against immediately terminating employees who refuse the vaccine, calling that a “last resort,” but reminded employers that they have an obligation to provide a safe workplace.

“So there’s an employee that is creating an unsafe work environment. There are consequences for that. But I would definitely advise consultation with with legal experts in employment law,” said Farnitano.

General Counsel and Senior Vice President of Tech and Innovation at the Silicon Valley Leadership Group Peter Leroe-Munoz applauded the health officers’ decision that gives businesses flexibility as they finalize return to work plans.

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“I think what is good about this kind of approach, versus a mandate, is it allows the companies themselves who best know their circumstances, who best know their employees, and best know their office culture to decide what is most prudent for them,” said Leroe-Munoz.