The Italian club initiated tests after forward Manolo Gabbiadini tested positive for the coronavirus on Thursday.
Omar Colley, Albin Ekdal, Antonino La Gumina and Morten Thorsby, as well as club doctor Amedeo Baldari, were confirmed as infected by COVID-19.
La Samp confirmed the players and Baldari are recovering at home in Genoa.
The remaining players from the Serie A team, as well as additional staff and club directors, have been placed in self-isolation. Sampdoria's training ground and offices have been closed, with Italy in lockdown because of the virus.
The Italian top-flight has been suspended until April 3 after a governmental decision on health grounds. Sampdoria are currently placed 16th, only one point above the relegation zone.
England's Premier League has also been halted due to the coronavirus after an emergency meeting on Friday, joining La Liga, the Dutch Eredivisie, Liga NOS and the MLS in suspending their competitions.