"During the tests to which the footballers were subjected, three new cases of Covid-19 emerged, with one player testing positive again," Sampdoria said in a statement.
Top clubs in Italy are testing team members and staff as they prepare to return to training facilities this week for individual sessions.
Earlier Fiorentina had revealed that three players and three of the club's staff had tested positive for the virus, taking this week's tally among Italy's top flight clubs to eight after Torino announced on Wednesday that one player had the virus, as well as AC Milan.
Five Samp players - Omar Colley, Albin Ekdal, Morten Thorsby, Antonio La Gumina and Manolo Gabbiadini - had previously suffered from Covid-19, along with the club doctor.
Three Fiorentina players - Patrick Cutrone, German Pezzella and Dusan Vlahovic - also tested positive for coronavirus in March, but have since been given the all-clear.