The Occupational Safety and Health Administration, which previously made it clear that employers can require coronavirus vaccinations as a condition of employment, has released new guidance for employers to clarify matters further.

In its new release, the agency deals with the rare possibility of an adverse reaction to a mandated vaccination. In that case, the reaction counts as work-related.

The practical upshot of that guidance is that in some cases — typically when an adverse reaction involves days away from work, restricted work or transfer to another job, or medical treatment beyond first aid — the adverse reaction will be "recordable," according to the agency. That is, it needs to become part of a record of serious work-related injuries and illnesses that OSHA requires most companies with more than 10 workers to keep and make available to workers, though certain low-risk industries are exempt from the requirement.

The records must be maintained at the work site for at least five years, according to OSHA. Each February through April, employers must post a summary of the injuries and illnesses recorded the previous year.

Employers that merely recommend vaccination to their workers rather than require it aren't required to record an adverse reaction as work-related, however.

OSHA further stipulates that for that distinction to apply, the vaccine must really be voluntary.

"For example, an employee’s choice to accept or reject the vaccine cannot affect their performance rating or professional advancement," OSHA noted. "An employee who chooses not to receive the vaccine cannot suffer any repercussions from this choice."

An adverse reaction isn't recordable even if an employee who wasn't required by the employer to be vaccinated happened to receive the vaccine at work, as opposed to an off-site location such as a local health department or pharmacy. The important question is whether the vaccination was a condition of employment.