ATHENS, Greece—Greece imposed a vaccination mandate Monday for people 60 and older, as the country’s vaccination rate remains below the European Union average and a spike in infections has put sustained pressure on Greek hospitals. Older people failing to get vaccinated will face penalties, starting at a 50-euro ($57) fine in January and followed by a monthly fine of 100 euros ($114) after that. About two-thirds of Greece’s 10.7 million people are fully vaccinated, while the EU average is just over 70 percent. But COVID-19 deaths and daily hospitalizations have increased following the arrival of the highly contagious omicron variant, though pressure on ICU capacity has eased slightly. Health Minister Thanos Plevris said the fines would be collected through the tax office with the money going to help fund state hospitals. “The age factor is important because of its impact on the public health service,” Plevris told private Open TV …