Employers cannot require workers to submit to antibody testing before returning to work, the federal government said.

Updated guidance from the Equal Employment Opportunity Commission said that an antibody test constitutes a medical exam under the Americans with Disabilities Act and, therefore, an employer cannot require it.

"Antibody test results 'should not be used to make decisions about returning persons to the workplace,'" the EEOC said, citing CDC guidance.

"An antibody test at this time does not meet ADA's 'job related and consistent with business necessity' standard for medical exams or inquiries for current employees."

While an antibody test is not allowed, the ADA does allow employers to take employee temperatures and perform tests to determine if employees have the virus, the EEOC said.

"The ADA requires that any mandatory medical test of employees be 'job related and consistent with business necessity,'" the EEOC said.

"Applying this standard to the current circumstance of the COVID-19 pandemic, employers may take steps to determine if employees entering the workplace have COVID-19 because an individual with the virus will pose a direct threat to the health of others."