The Occupational Safety and Health Administration's temporary standard requiring companies with 100 or more workers or more to have a vaccine mandate began on Monday.
Affected companies can also require unvaccinated employees to test weekly if they have the resources to monitor that.
"They have to get information and proof from employees of their vaccination status, employers have to give employees time off to get vaccinated with pay, pay for the employee's time off if they get ill from getting vaccinated, and also if the employer so chooses and it looks like this is up to the employer, the employer can opt to have a testing program for non-vaccinated people," said Frank Clowney, an employment attorney.
Get top local stories in San Diego delivered to you every morning. Sign up for NBC San Diego's News Headlines newsletter.
Many major private companies across the United States already have vaccine mandates in place, but this new temporary standard from OSHA would most likely be enforced by the workers, according to employment attorneys.
"There's no policing policy written into this temporary standard, so the most likely thing that would happen is if an employer is, say, not following the standard, that an employee would perhaps report the employer to OSHA," Clowney said. "That’s the most likely enforcement mechanism that I can see."
What about employees who choose to remain unvaccinated but their companies decide not to offer an option for them to get tested weekly?
"It doesn’t say in the law that employers have to fire people who aren’t vaccinated, but they have to have a policy that ensure vaccination, so it looks like that would be part of most policies," Clowney said.
On Friday, the Supreme Court heard arguments about whether the vaccine mandate for private employers was Constitutional.
"We’re already starting to feel the different positions, and I think the main one is that the federal government is making an overreach in trying to make a mandate and forcing employees to get vaccinated," said Aaron Olsen, an employment attorney. "There is very little precedent. There is some precedent for it going back a long time ago, dealing with smallpox."
As of right now, the Supreme Court has not upheld any of the lower courts stays on the mandate, which means it is effective beginning Monday, but many believe the Supreme Court could rule on this later this week.
Estimates show the vaccine mandate for companies with 100 workers or more would impact approximately 84 million Americans.