WASHINGTON - The number of people infected with the coronavirus is rising sharply in the United States. But the number of people dying is flat.

It sounds like good news. But experts warn against reading too much into it.

The number of new cases has seen a steady rise since mid-June. The seven-day average now tops 50,000. But the death toll from COVID-19, the disease caused by the virus, has been on a shallow decline through that period. It now averages around 500 per day.

But it takes several weeks for COVID-19 to kill, doctors note. Hospitalization numbers started to rise less than three weeks ago. They are up nearly a third since then, according to the COVID Tracking Project.

Deaths will likely follow, said Amesh Adalja, a senior scholar at the Johns Hopkins University Center for Health Security.

"I do think that just by simple biology and mathematics, we will see death counts increase as hospitalizations and ICU bed use increase," he said.

Young and infected

One reason the death count may be lower is that many of the people who are infected are young and less likely to develop severe disease. In some places, they now make up the majority of new cases.

"The death rate is lower, I admit that, because people in general who are young are healthier," National Institute of Allergy and Infectious Diseases Director Anthony Fauci said on a Facebook Live news conference Tuesday. "But that doesn't mean that you could not get seriously ill."

Young people do end up in intensive care units and die of COVID-19, but at lower rates.

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"And there's a whole host of issues that we're also just learning about," Columbia University epidemiologist Barun Mathema said, including long-term lung damage.

"There's a lot in between being asymptomatic and dying," he said.

Asymptomatic transmission

Since people are infectious before they show symptoms, young people can spread the coronavirus that causes the disease without knowing it.

"Every 20-year-old has an uncle, an aunt, a grandma, a grandpa," Mathema noted. It may take a while, but "at some point, this may translate into transmission chains into these already vulnerable populations," including the elderly and people with other health problems.

Young people have drawn criticism for ignoring precautions and congregating without masks in bars, clubs, parties and other crowded spaces. They are seeing higher infection rates because of it.

They may make up a bigger proportion of new infections because, "it is possible that older people and those who are more vulnerable are more careful in terms of their behaviors," said University of Miami professor of medicine Maria Luisa Alcaide, a spokesperson for the Infectious Diseases Society of America.

One of the most vulnerable groups - nursing home residents - was hit hard early in the pandemic. Nursing homes account for more than 40 percent of COVID-19 deaths, according to an analysis from USA Today and others.

But infection control at these facilities has tightened substantially since then.

"We've gotten much better at fortifying our nursing homes against this virus," Adalja of Johns Hopkins said. That could mean fewer deaths as cases spike, he added.

Better treatment

Fewer people may be dying of COVID-19 because treatment for hospitalized patients has improved somewhat since March.

"We know a lot about the complications that coronavirus can cause, such as strokes or blood clots in the lung. And we know how to somewhat prevent those complications," Adalja said.

Studies have shown two drugs, remdesivir and dexamethasone, can offer some help. But only some.

"Once you're very, very ill, those are effective drugs. They're not cures," said Harvard Medical School professor Rajesh Gandhi, co-author of the Infectious Diseases Society of America's COVID-19 treatment guidelines. "These drugs have an impact. It's an important impact, better than we were in March. But we have a long way to go to get treatment where we want it to be."

"We are still seeing some very sick people," IDSA's Alcaide said. "It's going to take a little bit longer to see if this increase in cases is also going to lead to an increase in deaths."

"We still have to think that we are dealing with a very, very aggressive virus with a high mortality," she added.