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March 19, 2020

Millennials may be spreading coronavirus unknowingly – to the detriment of seniors

Asymptomatic transmission is playing a bigger role in the pandemic than previously believed

Prevention Coronavirus
Millennials coronavirus asymptomatic spread Matias J. Ocner/Miami Herald/TNS/Sipa USA

People in their 20s and 30s, as well as younger generations face a very low risk of dying from COVID-19. But they may be spreading of coronavirus without realizing it, health officials warn. Above, visitors gathered at Miami's South Beach on Monday despite some areas having restrictive access.

Millennials and younger generations face a very low risk of dying from COVID-19. But they may be playing a significant role in the spread of coronavirus without realizing it.

Andreas Backhaus, a Belgium economist, examined the age demographics of confirmed coronavirus cases in South Korea and Italy, two of the most-heavily impacted countries. He found stark differences.

In South Korea, people in their 20s accounted for nearly 30% of the country's cases. But in Italy, they only accounted for 3.7%. One possible explanation for that disparity? Italy's testing strategy has failed to reveal younger people with mild or asymptomatic cases.

Backhaus explained on Medium:

"Italy has predominantly been testing people with symptoms of a coronavirus infection, while South Korea has been testing basically everyone since the outbreak had become apparent. Consequently, South Korea has detected more asymptomatic, but positive cases of coronavirus than Italy, in particular among young people."

The frequency of asymptomatic cases – and the contagiousness of asymptomatic people – remains unclear. But U.S. health experts are now saying that asymptomatic and pre-symptomatic transmissions are fueling more coronavirus cases than previously believed.

That poses a danger to the most vulnerable populations – the elderly and people with underlying medical conditions. And it emphasizes the need for younger generations, who are more likely to only develop mild symptoms, to practice social distancing.

"For the asymptomatic people, are they as contagious as the symptomatic people? Probably not," Dr. Peter Axelrod, an infectious disease specialist at Temple University Hospital, told PhillyVoice. "But if you have 10 people who are less contagious, that's probably worse than having three people who are more contagious."

Dr. Deborah Birx, the White House coronavirus response coordinator, acknowledged Monday that there is "a large group" of people who are asymptomatic or have mild cases of COVID-19. 

  • SYMPTOMS: Coronavirus vs. Other respiratory illnesses
  • CORONAVIRUS SYMPTOMS
    • Fever, cough, shortness of breath
  • SEASONAL ALLERGY SYMPTOMS
    • Itchy eyes, stuffy nose, sneezing
  • INFLUENZA SYMPTOMS
    • Fever, cough, body aches, fatigue, chills, headache and possibly sneezing, stuffy nose and a sore throat
  • COMMON COLD SYMPTOMS
    • Sneezing, stuffy nose, sore throat and possibly coughing, slight aches, fatigue, fever
  • Anyone with coronavirus symptoms should stay home and call their doctor. More information can be found on the CDC's website. Philly residents can text "COVIDPHL" to 888777 for updates on the coronavirus, and anyone in Greater Philadelphia can call the coronavirus hotline at 800-722-7112.

That reality spurred the Trump administration to recommend people of all ages avoid unnecessary travel and refrain from visiting bars and restaurants. Various states, including Pennsylvania and New Jersey, have instructed all schools and non-essential businesses to close.

Birx particularly urged millennials to practice social distancing even if they're feeling healthy. She asked them to keep gatherings to less than 10 people – even within their homes.

"They are the core group that will stop this virus," Birx said at a news briefing. "They’re the group that communicates successfully, independent of picking up a phone. They intuitively know how to contact each other without being in large social gatherings."

Donovan Mitchell, a 23-year-old NBA player who tested positive for coronavirus, told "Good Morning America" that he hasn't developed any symptoms. He has used Twitter to urge people to stay inside their homes, noting his disappointment that many bars and beaches were packed last weekend.

"I could walk down the street (and) if it wasn't public knowledge that I was sick, you wouldn't know it," Mitchell said. "I think that's the scariest part about this virus. You may seem fine, be fine. And you never know who you may be talking to, who they're going home to. 

The United States had 9,345 coronavirus cases, including 137 deaths through Wednesday. Pennsylvania had 155 cases; New Jersey had 427 including three deaths.

Several international studies have affirmed that asymptomatic and pre-symptomatic transmissions may be occurring at significant rates.

One study estimated that 48% to 66% of a cluster of 91 coronavirus cases in Singapore were contracted from people who did not yet have symptoms. It also found that 62% to 77% of a cluster of 135 coronavirus cases in Tianjin, China came from people who were pre-symptomatic.

In the United States, asymptomatic transmission at a Biogen company meeting is believed to have sparked an outbreak of several dozen cases in Massachusetts.

Halting such spread – and mitigating the death toll – requires the more stringent strategies being implemented across the United States, Axelrod said. But he acknowledged they carry personal, logistical and economic consequences.

"I think they're a gigantic pain in the neck," the Temple doctor said. "I think they're very difficult for people financially, especially people who don't get paid if they don't show up for work. I think they're horrible, but I think they're a good idea. ... I can't think of any other way of containing this, short of a vaccine, which we don't have."

Though most younger adults can weather the effects of the coronavirus, people older than 60 are at increased risk of severe illness. The situations in Italy and South Korea underscore this difference.

"If the virus spreads predominantly among young people, as appears to have been the case in South Korea, there is no immediate risk of collapse to the hospitals," Backhaus wrote. "However, if it spreads to the old population, as in Italy, collapse is looming; and it might be a matter of days."

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