As states across the country start to ease up on coronavirus closures and restrictions, including Massachusetts, testing is playing a major role in deciding how much and how soon the economy can be reopened safely. But an emergency room physician at Boston’s Brigham and Women’s Hospital argues another metric — called excess mortality — shows “we’re still in the thick” of the pandemic.

“Excess mortality is the concept that says we know, actually, every week of every month of every year, just about how many people are expected to die,” Dr. Jeremy Faust told Jim Braude on WGBH News’ Greater Boston Monday.

“We know what those numbers should be like,” he said. “For the first time in, really, modern history, we are seeing an absolutely gigantic deviation from that.”

In the H1N1 outbreak of 2009, for example, the number of flu deaths was not large enough to show a substantial difference between total deaths that year from total deaths of years prior, Faust explained. But the deaths from COVID-19 — which killed more than 5,000 people in Massachusetts as of Monday — have shown a major difference, even as data collection lags behind analysis.

“At the moment, it’s so bad that even with the incomplete data that we have, we’re already over the numbers we should be,” said Faust. “Usually, it takes seven to fourteen days for things to settle out, but you know if, on day one, you’re already over your average, you’re in trouble.”

Faust, who is also an instructor at Harvard Medical School, believes excess mortality should be added to the epidemiological toolbox of those deciding when to reopen. But he says other tools, like testing and contact tracing, shouldn’t be discounted either.

President Trump questioned the merits of testing Friday, telling reporters “the whole concept [isn’t] necessarily great” because “something can happen between a test where it’s good and then something happens.”

But Faust said the president was missing the obvious need for repeated testing.

“We need to test people more than once in some cases. Just because you weren’t pregnant two months ago doesn’t mean you’re not expecting today,” he said. “Except in this case it’s coronavirus, which could kill your neighbor or you. … The number of tests we need to have to be safe is far higher than what we have today.”

It’s a concept the White House has been implementing in recent days, after a few positive cases among staffers who work close with President Trump and Vice President Mike Pence prompted increased testing.

“I’m glad to hear the White House thinks this is a priority, they’re testing themselves — that’s a very good sign that shows they believe in the utility of testing,” Faust said.

The president also downplayed the importance of a coronavirus vaccine Friday, saying the coronavirus pandemic is “going to go away” without one.

Faust said he believes that Trump’s statement doesn’t reflect his administration’s official policy toward a vaccine, but the idea of abandoning that effort isn’t worth entertaining.

“I think a vaccine is our best hope. We should all be watching that very carefully,” he said. “I look forward to the day where you see people lining up. That’s going to be a moment, if and when that occurs, that’s going to be historic and positive.”