SAN FRANCISCO (CBS SF) — While some car traffic has returned to 1st Street in San Francisco, the sidewalks of the Financial District remain fairly quiet. That could change next month when Salesforce Tower reopens for small vaccinated groups of employees.

The questions that remains is whether workers are ready to part with their sweatpants and actually return to an office.

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Salesforce is planning to re-open offices in mid-May to vaccinated workers. The company plans to fully re-open offices when new cases are below one percent and will allow employees the option to keep working remotely through the end of 2021.

UCSF epidemiologist Dr. Monica Gandhi tells KPIX it will be safe.

“The CDC said for a reason that vaccinated people can be around each other without masks and distancing and that is because the vaccines are so incredibly effective at preventing you from getting severe disease,” said Dr. Gandhi.

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Some universities will mandate students have a COVID-19 vaccine before returning to campus. Law professor Dorit Reiss of UC Hastings says employers can do the same.

“Vaccine mandates in the workplace are not new. Generally, vaccine mandates are legal; a workplace condition to increase health and safety. They are just as legal as requiring hand washing,” Reiss told KPIX.

Employer mandates could face legal challenges from those with sincere religious objections to vaccination.

Another potential issue is the fact that none of the vaccines on the market has full FDA approval yet. The Pfizer, Moderna and Johnson & Johnson vaccines currently only have emergency-use authorization from the Federal Drug Administration.

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“I think it will lead to more legal challenges on exactly that ground because it’s an emergency use authorization. But I don’t know how long for because Pfizer has mentioned it’s going to apply for a biological license,” Reiss said.