The Occupational Safety and Health Administration regulations will force the companies to require that unvaccinated workers test negative for COVID-19 at least once a week and wear a mask while in the workplace. FILE - A health worker administers a dose of Pfizer/BioNTech COVID-19 vaccine to a woman at a vaccination center. RELATED: Merck COVID-19 pill: UK authorizes antiviral in world's 1st approval of drugThe agency will face enforcement challenges. Employers covered by the requirements must verify their workers’ vaccination status by checking documents such as CDC vaccination cards or records from doctors or pharmacies. He has touted businesses that announced their own vaccine requirements and urged other companies to follow their lead.