MADRID—Spanish regions are bringing back curfews as well as restrictions on socializing and nightlife after a sharp rise in coronavirus infections. Catalonia and Valencia, two Mediterranean coast regions with major virus outbreaks, are limiting social gatherings to 10 people and restoring late night restrictions on all activities, while the northern region of Asturias on Monday banned indoor bar and restaurants operations. Spain’s two-week COVID-19 caseload is now over three times higher among people under 30 than the average. The closely watched variable rose nationally on Monday to 368 cases per 100,000 residents, according to Fernando Simón, who coordinates Spain’s response to health emergencies. Simón said although younger patients typically don’t need intensive care treatment, the high number of cases among under 30s was slowly pushing up the rate of hospital admissions. “We are not recording an increase in mortality—and we hope that we don’t reach there,” he told reporters. Simón …