The Department of Veterans Affairs, the nation's largest health care system, is seeing an onslaught of coronavirus patients. The department, which cares for millions of elderly veterans, has now confirmed nearly 500 cases — a 60% spike since Tuesday.

In Philadelphia, the challenge is stark: serving a population of 55,000 vets with 102 beds.

Karen Flaherty-Oxler, the retired rear admiral who runs the VA center in Philadelphia, told CBS News that the department was able to expand by about 50 beds — but when asked if that would be enough, she said, "We're not sure."

The average veteran served by the VA is older than 60. And many have underlying health conditions, making them especially vulnerable to respiratory issues from coronavirus.

When asked if there were enough ventilators, Flaherty-Oxler said the department has some on order.

"We put in an order in anticipation that 30 or 40 percent of the veterans we see may need some ventilatory support," she said.

"Are you anticipating a crisis?" CBS News asked.

"I'm not," Flaherty-Oxler said.

The Philadelphia VA emphasized that it has been providing primary care for years and tracking veterans who are most vulnerable, so it is prepared to treat those veterans if they contract the virus.

But Dr. Lewis Kaplan, a surgeon at the Philadelphia VA medical center, said that when their patients get sick, "they get really sick."

"Our typical patient might have heart disease and peripheral arterial disease…" Kaplan added. "So we worry [...] when they need care that they're going to be a challenging patient to look after, and some of them really are."

"Does 150 beds seem like enough for 50,000-plus veterans?" CBS News asked.

"I hope it is," Kaplan responded. "I'm worried that it's not."