Most coronavirus cases are spread by people without symptoms, CDC now says

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Sat, 2020-11-21 14:57 — mike kraft

Most Covid cases spread by people without symptoms, CDC now says Most Covid-19 infections are spread by people who have no symptoms, the CDC says in newly updated guidance. Maggie Fox, CNN CNN

(CNN)Most coronavirus infections are spread by people who have no symptoms, the US Centers for Disease Control and Prevention said in newly updated guidance.

It's one of the main reasons mask use is so important, the CDC said.

"Most SARS-CoV-2 infections are spread by people without symptoms," the agency said in a section of its website devoted to explaining the science of how to use masks to control the spread of the virus.

"CDC and others estimate that more than 50% of all infections are transmitted from people who are not exhibiting symptoms," it added in the guidance posted Friday.

"This means at least half of new infections come from people likely unaware they are infectious to others."

According to the CDC, 24% of people who transmit the virus to others never develop symptoms and another 35% were pre-symptomatic. It also said 41% infected others while experiencing symptoms.

Peak infectiousness comes five days after infection, the agency said on the website. "With these assumptions, 59% of infections would be transmitted when no symptoms are present but could range (from) 51%-70% if the fraction of asymptomatic infections were 24%-30% and peak infectiousness ranged 4-6 days."

It cited a study published in July in the Proceedings of the National Academy of Sciences and as-yet unpublished CDC data. Previously, the health organization has not characterized what percentage of infections are spread by symptomless people. ...

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