Madubuike, Houston among Ravens placed on COVID-19 list
Ferguson tested positive Friday morning, which resulted in Baltimore undergoing contact tracing, according to ESPN's Jamison Hensley.
The vaccination status of those players is unclear, but it's unlikely they will be available to play Sunday against the Detroit Lions.
Fully vaccinated players who test positive and are asymptomatic need two negative tests 24 hours apart to return, while unvaccinated individuals are subject to a mandatory 10-day quarantine.
Unvaccinated players who are ruled high-risk close contacts must sit out at least five days and can return after a negative test.