MADRID — Just last weekend, about 120,000 people marched through downtown Madrid to celebrate International Women’s Day. Some 60,000 soccer fans filled one of the city’s largest stadiums. And 9,000 supporters of Vox, Spain’s third-largest party, gathered inside a former bullring.

Now Spain has the second-highest number of coronavirus infections of any European country, after Italy — overtaking the larger nations of France and Germany — and faces the fastest spreading contagion on the Continent.

Between last weekend and Friday, the number of cases in the country shot from several hundred to 4,200, with 120 deaths, and the prime minister warned that the number of cases could reach 10,000 by next week. That would give Spain one of the fastest rates of coronavirus contagion in the world.