Five Sampdoria players recovered from coronavirus last month, but they now have four cases, including a second positive test for one player.
Four Sampdoria players have tested positive for coronavirus, one of which had previously recovered from COVID-19.
Serie A is attempting to ramp up its preparation for a return to action, with the season having been suspended since March.
Germany's Bundesliga will restart next week, and Italian clubs are testing their players in order to move forward with plans to get the season back up and running.
Torino revealed a positive test had been returned by a player on Wednesday, before Fiorentina confirmed six cases – including three players – on Thursday.
Sampdoria, who announced a clean bill of health last month after five players had recovered, then issued their own update, confirming they had quarantined four asymptomatic members of their squad.
"UC Sampdoria informs that, during the tests to which the players were subjected, three new positive results for COVID-19 and one return of positivity emerged," a statement read.
"Currently asymptomatic, they have been placed in quarantine and will be constantly monitored as per protocol."
Manolo Gabbiadini, Omar Colley, Albin Ekdal, Antonino La Gumina and Morten Thorsby previously tested positive, but Sampdoria did not disclose the identity of the latest cases.