MADRID, Dec 17 (Reuters) - Spain"s coronavirus infection rate rose above 500 cases per 100,000 people on Friday, crossing over the threshold considered "very high risk" by the Health Ministry and more than doubling since the start of December. On Friday the infection rate, or incidence, as measured over the preceding 14 days, was 511 cases per 100,000, up 38 points on Thursday"s 473. There were 33,359 new infections and 41 deaths according to Health Ministry data. Roughly 80% of Spain"s population of 47 million has been fully vaccinated against COVID-19, and some 10 million have received booster shots. On Thursday Spain approved booster vaccines for people aged over 40. read more Spain has recorded 5.46 million cases and 88,708 deaths since the pandemic began.