“I said, ‘My gosh, if this thing really does take root in the United States then, here in Brooklyn, we’re going to have a problem,’” he recalled.

Not only did Dr. Riley worry about the resources that would be needed to provide care during a pandemic, he feared that the hospital’s patients would be particularly susceptible to the disease.

The central Brooklyn neighborhoods where most of University Hospital’s patients live, East Flatbush and Prospect Lefferts Gardens, have higher-than-average concentrations of chronic diseases like diabetes, hypertension and obesity, which preliminary studies have shown make Covid-19 most deadly.

The hospital opened in 1963 and it was meant to accommodate about 60,000 visits a year. Despite having almost no physical improvements, it now handles about 200,000 visits annually. The bunkerlike concrete building is crumbling from within. Earlier this year, a leaky roof forced a temporary evacuation of premature babies from a neonatal intensive care unit.

“It is too, too old compared to other hospitals across the water,” Dr. Riley said. “We need a new hospital to be prepared for the next pandemic and to better serve our community.”

Signs inside the hospital are written in English, Spanish and Creole, a reflection of the large number of immigrants in the area, particularly from the West Indies.

Many of the patients work but are poor or receive government assistance. Many are uninsured and use the hospital for emergencies and primary care. They come from a men’s shelter up the street or from a nearby home for domestic violence survivors to fill prescriptions or to have their diabetes checked.