The people – an Argentinian, an Italian, a Briton and his travel companion – have been kept under observation after the virus outbreak aboard the Hondius cruise ship. They had come into contact in various ways with people suspected of being infected with hantavirus, Reuters reported.
For two of them, the contact occurred during a flight with an infected woman who had been on board the Hondius and who died last week.
All four have now tested negative.
"The risk of contracting the virus remains low in Europe and is therefore also low in Italy," a statement from Italy's health authority said.
