If fully vaccinated, Ferguson would need two negative test results 24 hours apart to return, as long as he is asymptomatic. If unvaccinated, he must self-isolate for a minimum of 10 days.
Under the NFL's COVID-19 protocols, unvaccinated players who are identified as high-risk close contacts must remain away from the team for five days. Vaccinated players don't have to quarantine if they are a close contact.
The Ravens will be down to just two healthy outside linebackers -- Odafe Oweh and Tyus Bowser -- and three active defensive linemen -- Calais Campbell, Justin Ellis and Broderick Washington -- for Sunday's game against the Detroit Lions.
Baltimore could opt to call up outside linebacker Chris Smith and defensive tackle Kahlil McKenzie from its practice squad before Sunday's matchup.