In the week ending Sunday, new hospital admissions increased 38% compared to the previous week. They had risen 17% in the week ending Aug. 1 and 10% in the week ending July 24. It’s a worrisome trend, said Talia Quandelacy, an assistant professor at the Colorado School of Public Health. “If you weren’t masking indoors, in particular in crowded spaces, it would be a good idea,” she said.