Dr. Fauci says it will take 'months to a year or more' to know whether lingering COVID-19 symptoms in young people could be chronic illnesses

• In an interview with Mark Zuckerberg on Thursday, Dr. Anthony Fauci highlighted the range of coronavirus symptoms among young people.
• Some young coronavirus patients "can be knocked on their back and brought to their knees pretty quickly," Fauci said.
• He added that it could take "months to a year or more" to determine whether these patients now have chronic illnesses.

Most young people infected with the coronavirus won't become seriously ill, but a growing number of them have reported being sick for weeks on end. The nation's top disease expert, Dr. Anthony Fauci, said it may take a while to know whether they have long-term illnesses.

"It's the people who really get knocked out badly, particularly those who require hospitalization, that it's going to take months to a year or more to determine if there are any long-lasting, deleterious consequences of the infection," Fauci said during a conversation with Facebook CEO Mark Zuckerberg on Thursday. "We just don't know that now. We haven't had enough time."

There's recently been a drastic rise in coronavirus infections among young adults in the US. People in their 20s, 30s, and 40s represent roughly half of cases in coronavirus hot spots like Arizona and Texas, while people ages 18 to 34 represent more than a third of cases in Florida and California.

"If you look at what's going on with the new infections, the median age is about a decade and a half younger than it was a few months ago," Fauci said, adding that this could have dangerous effects on transmission.

"My message to young people is consider your responsibility to yourself, but also the societal responsibility," Fauci said. "By allowing yourself to get infected, you are propagating the pandemic."

Fauci said some patients may develop 'postinfection syndromes'

As coronavirus cases have risen, doctors have identified a wider range of symptoms among patients in their 20s, 30s, and 40s.

"I've never seen an infection with this broad range of manifestations," Fauci said. Some young people, he added, "can be knocked on their back and brought to their knees pretty quickly."

The number of coronavirus hospitalizations among 18- to 29-year-olds is four times what it was a few months ago: about 38 hospitalizations out of every 100,000 people as of July 4, compared with nine out of every 100,000 people on April 18.

A new study from researchers at the University of California at San Francisco found that one in three young adults ages 18 to 25 were vulnerable to severe COVID-19 cases because of factors like smoking habits or preexisting illnesses. But even young, healthy nonsmokers have reported feeling sick for several months, with lasting symptoms like chest pain and shortness of breath.

Fauci said some patients may have "postinfection syndromes" that resemble chronic fatigue syndrome, which is often characterized by cognitive impairment, muscle pain, and a debilitating lack of energy. In June, doctors in the UK also warned of postviral syndromes among coronavirus patients.

"You have to separate the damage from the disease," Dr. Ramzi Asfour, an infectious-disease doctor in Marin County, California, previously told Business Insider. "The symptoms are probably coming from an immune reaction."

Asfour said he'd seen college-aged patients with mononucleosis who've had severe fatigue for two years, or viral infections that triggered a lifelong autoimmune disease like lupus or rheumatoid arthritis. The coronavirus could have similar effects on patients, he said.

"It's different for different people," he added. "Usually, time heals. But not necessarily always."