People who don’t show COVID-19 symptoms account for more than half of all coronavirus transmissions, according to a new study from the U.S. Centers for Disease Control and Prevention.

A look at the study:

The study — published Thursday in the peer-reviewed journal JAMA Network Open — looked at transmission numbers and found:

  • Thirty-five percent of transmission came from presymptomatic individuals.
  • Twenty-four percent came from people who never developed symptoms.
  • In total, 59% came from people without symptoms.
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The experts who conducted the study said washing your hands, wearing a face mask, social distancing and more testing of people who aren’t sick “will be foundational to slowing the spread of COVID-19.”


Dr. David Hooper, chief of the infection control unit at Massachusetts General Hospital, told USA Today he agreed with the idea.

  • “(SARS-CoV-2) is a virus that’s quite transmissible and less forgiving of any lapses of use of masks and social distancing and hand hygiene,” he said.
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Key to the spread:

Jay C. Butler, the CDC deputy director for infectious diseases and a co-author of the study, said that the key to stopping the spread of the virus requires people to stop transmission between each other.

  • “The bottom line is controlling the COVID-19 pandemic really is going to require controlling the silent pandemic of transmission from persons without symptoms,” he said. “The community mitigation tools that we have need to be utilized broadly to be able to slow the spread of SARS-CoV-2 from all infected persons, at least until we have those vaccines widely available.”