UPDATE (Dec. 7) -- The Baltimore Ravens activated quarterback Lamar Jackson, fullback Patrick Ricard, long snapper Morgan Cox and defensive tackle Justin Madubuike from the Reserve/COVID-19 list.Baltimore Ravens quarterback Lamar Jackson is expected to start in Tuesday night's Dallas Cowboys game, ESPN reported citing a source.ESPN and WBAL Radio's Jamison Hensley reported Jackson is eligible to be activated off the Reserve/COVID-19 list Sunday after having tested positive for the coronavirus on Thanksgiving.Coronavirus impacts Ravens hardThe team is reporting that there were four different strains of the virus in their facilities and that three of the strains were stopped with only one causing the outbreak in the facility.At least one player tested positive for 10 straight days, and nearly two-dozen were added to the Reserve/COVID-19 list.The team's president, Dick Cass, released a statement Saturday saying, in part: "We cannot undo what has occurred, but we can do our best to learn from what has happened and be vigilant moving forward to ensure that it does not happen again. As the recent experience has shown us, this virus does not need a large opening to spread within an organization, and 99% compliance is not a passing grade when dealing with this virus."Dr. Andrew Pekosz, a professor of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health, said experts can learn from the different mutations of COVID-19 and how it could help stop the spread."One of the great things was they were able to use those mutations to actually track exactly who got the virus from whom. And that's going to be useful because then they can go back and look at their interventions, see where the weak parts were and be able to identify who gave the virus to who, during what period of time and what were the conditions there," Pekosz said.Pekosz said COVID-19 will continue to mutate and the best way to protect yourself is by following COVID guidelines, like wearing face coverings and practicing social distancing.Ravens prepare for Tuesday's game against CowboysThe Cowboys game was rescheduled twice as a result of the Pittsburgh Steelers game being postponed three times.Robert Griffin III was put on injured reserve after injuring his hamstring during the Steelers game. Ravens head coach John Harbaugh said after practice Sunday that he is comfortable if the Ravens have to go with Trace McSorley at quarterback on Tuesday night.With Griffin going on injured reserve, that would also mean activating practice squad quarterback Tyler Huntley as a backup.Also, the return of Calais Campbell and Brandon Williams to the active roster should help the defense considerably. And for everyone, simply returning to regular, daily practice and the rhythm of a routine is a major upgrade this week."Today's practice, even though it was indoors, we didn't get the cold, I just didn't want to deal with that wind today. It's not going to be that windy in the game, so it just wasn't worth it to go our there and fight the wind. I wanted to have a more appropriate practice. We had the doors open, we tried to get the temperature approximated. We had a good, sharp practice, the guys were into it, (there was) a lot of energy. It was a good practice," Harbaugh said.The Ravens, at 6-5, have lost three straight games and stands third in the AFC North, while the Cowboys are in last-place in the NFC East at 3-8. Tuesday's game is in Baltimore and is scheduled for 8:05 p.m. Tuesday.