Four patients in Greece died of an influenza virus while more than a dozen others have been hospitalized, Greek health authorities announced on Friday. Three of the victims were infected by the H1N1 flu which had triggered alarm worldwide four years ago, experts of the Greek Center for Disease Control and Prevention said. The fourth man had been infected by the same type B flu which has swept other countries this winter. Health officials advised in particular members of high-risk groups, such as elderly and underage persons suffering from cardiovascular or respiratory illnesses, to get vaccinated. Experts estimate that the cycle of the seasonal flu in Greece will close by late March.