The CDC’s announcement that fully-vaccinated individuals don’t need to wear a mask in most situations was a big step toward a return to normalcy, but it might have complicated employers’ return-to-work plans.

“The news makes it so much more complex for companies to navigate their re-openings now,” said Brian Kropp, chief of research for the Gartner Human Resources Practice.

Generally speaking, employers can mandate workers get vaccinated and require proof of inoculation before they return to the office. But federal protections allow for some exceptions. Workers with underlying medical conditions might be exempt under the Americans with Disabilities Act. And Title VII of the Civil Rights Act could allow employees with “sincerely held” religious beliefs against a vaccine to seek accommodations.

The new guidelines don’t prevent employers from requiring workers wear masks in the office. And some states and cities still have more strict mask mandates in place.

“If you are a private employer and you want to have safety restrictions that are greater than that required by the law, generally speaking you can do that,” said Erin McLaughlin, labor and employment attorney at Buchanan, Ingersoll & Rooney

She added that continuing a mask mandate might be easier. “If you are going to continue to require the mask, you don’t really have to deal with ‘has the person been vaccinated or not?’ and regulating who wears their mask.”

McLaughlin said that companies can have separate masking policies when it comes to vaccinated and unvaccinated workers.

“If you have a jurisdiction that has aligned with the CDC on the most recent guidance, you can have a policy that does not require masks for employees who have been completely vaccinated but still require them for those that haven’t,” said McLaughlin.

Policies about returning to the workplace, like vaccinations and mask wearing, need to be clear, said McLaughlin.

“Employers need to clearly communicate to their employees what the expectations are, apply them consistently and have frequent, likely changing communication with employees based upon the current state of the regulations and the jurisdictions in which you are operating,” she said.

When it comes to proof of vaccination, employers can’t require any additional medical information.

Adam Pankratz, an employment attorney and shareholder at Ogletree, Deakins, Nash, Smoak & Stewart, said there were three main tactics companies can take when asking for inoculation proof: request a copy of a vaccination card, have employees attest to receiving the shots, or have an honor system.

“This might mostly be smaller workforces where everybody knows each others’ names and family names,” he said of the honor system.

The new CDC guidance could also push more companies to mandate vaccines.

“I think the trend is gong to be more employers mandating now because of what happened yesterday,” said Mark Neuberger, an attorney at Foley & Lardner. “Nobody wants to wear a mask, more and more employers want to get their people back into the workplace so the easier way is to say: ‘you can come back and you don’t have to wear masks, just show me that you are vaccinated.’”