The entire team had been told to isolate after the cases were confirmed, however the club said in a statement that only a handful of players had to remain in quarantine.
The experienced left-back has signed a two-year contract after leaving Arminia Bielefeld.
The central defender left Fortuna Düsseldorf after seven years and has signed a two-year contract at the Wildparkstadion
It was a day of departures in the 2. Bundesliga on Thursday, with the most high-profile seeing Tim Kleindienst leaving 1. FC Heidenheim to join KAA Gent for an unspecified fee.
Fortuna Düsseldorf have completed their first signing of the summer, with Jakub Piotrowski joining from KRC Genk.
Fortuna Düsseldorf confirmed on Tuesday that they have handed a new, professional contract to Shinta Appelkamp.
Fortuna Düsseldorf confirmed on Monday that veteran Adam Bodzek will remain with the club next season.
Thursday was another busy day in the 2. Bundesliga with clubs confirming new deals and departures.
SV Sandhausen have moved quickly to replace Leart Paqarada, with Diego Contento signing on a free transfer.
Several clubs have started sending off their out of contract players with contracts expiring on Tuesday.