McPhee is the fourth Ravens player to receive the designation this week after J.K. Dobbins, Mark Ingram II and Brandon Williams went on the list Monday.
Baltimore announced earlier Tuesday it was sending players and staff members home and conducting necessary business remotely.
According to The Athletic's Jeff Zrebiec, McPhee may not be the last member of the Ravens to go onto the reserve/COVID-19 list:
Across the country, the number of new coronavirus cases is climbing ahead of the holiday season. The total number of cases in the United States so far is more than 12.5 million, with 259,045 people dead from the virus.
The NFL is taking some steps to mitigate the spread within teams.
All 32 franchises entered into the league's intensive protocol, which among other things requires players and staffers to have tested negative the day before in order to enter a team facility.
The NFL also tightened its COVID-19 protocols, mandating players wear face masks or coverings on the sideline unless they're wearing a helmet or preparing to enter the game. Coaches with play-calling duties will have to be masked as well, even if they wear a protective face shield.