CDC allows shorter quarantine: 10 days after exposure to COVID-19, 7 days with a negative test

CDC allows shorter quarantine: 10 days after exposure to COVID-19, 7 days with a negative test
A traffic sign reads "quarantine for 14 days" above a road in Brooklyn, New York, on October 25, 2020.Noam Galai/Getty Images, Business Insider
  • The US Centers for Disease Control and Prevention on Wednesday lowered its quarantine recommendations for people who've been exposed to someone with COVID-19.
  • The CDC used to say that people who've been exposed to others with COVID-19 needed to isolate for 14 days.
  • But there's a lot of new evidence that the infectious period for this virus in most people is shorter than that.
  • The CDC said 10 days is enough time in quarantine, or seven days if the person quarantining has a negative COVID-19 test in the final two days.

Forget about spending two weeks in quarantine if you've been exposed to the coronavirus — 10 days is enough, or one week with a negative test.

The US Centers for Disease Control and Prevention announced Wednesday that it would change its quarantine recommendations, asking people to isolate for at least 10 days if they've had close contact with someone who has COVID-19, the disease caused by the coronavirus.

People who've been exposed and who test negative on days five, six, or seven of their quarantine can resume normal life after one week, the CDC said, halving its original recommended quarantine time.
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The CDC suggested that a 14-day quarantine is still the safest and most effective way to prevent virus transmission.

"People should still watch for symptoms ... for a full 14 days after exposure," Dr. Henry Walke, the CDC's COVID-19 incident manager, said Wednesday on a call with reporters to explain the new quarantine guidelines.

But the agency now says the risk of passing on a coronavirus infection to other people decreases dramatically after day 10.
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"Ten days is where that risk got into a sweet spot we liked, at about 1%," Walke said. "That's a very acceptable risk, I think, for many people."

Seven days of quarantining with a negative test conducted during the final 48 hours lowered the risk of passing on an infection to others to about 5%, the CDC said. Studies from around the world have found that the most dangerous time for coronavirus infections to spread to new people is early in the illness, before and during the first week that someone is sick. That means it's far more important to have people following strict quarantine protocols when they are first coming down with COVID-19.
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That infectious period doesn't happen immediately after exposure to a sick person. It usually takes four or five days of incubation for people to start to get sick. (This is why test results gathered too early can be misleadingly negative.) People who are coming down with COVID-19 seem to be most infectious before and just as they start to show symptoms.

The new guidelines are likely less stressful and a bit more realistic.

"Many people are discontinuing quarantine ahead of time because there's pressure to go back to work, to get people back into school," Walke said on the call, acknowledging what he'd been hearing anecdotally from public-health workers across the country. "One of our hopes is that we can increase adherence with quarantine if we reduce the amount of time."
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14 days was a 'pretend' number, decided before scientists understood when this virus spreads most easily

CDC allows shorter quarantine: 10 days after exposure to COVID-19, 7 days with a negative test
Clean first, disinfect after.Getty

Dr. Rishi Desai, who used to teach people how to quarantine for the CDC, has said there was never any real precision to coronavirus quarantine rules, which were developed before scientists had a chance to study how and when the virus travels best between people.

"Fourteen is a pretend number, right? Like, why not 13?" Desai, the CEO of Osmosis, told Insider. "It's because it rounds to two weeks, and people can remember two weeks. So, there's no magical reason why 14 days was chosen other than it's just easy to remember."

People are most likely to pass their illness on to others just as they are beginning to feel ill. That's why wearing a mask has become such a key recommendation: It's easy to get other people sick before you know you're doing it.
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"You could be in the restaurant, feeling perfectly well, and start to get a fever," Mike Ryan, the World Health Organization's executive director of health emergencies, said earlier this year, explaining how this presymptomatic spread happens. "It's because the disease can spread at that moment that the disease is so contagious. That's why it's spread around the world in such an uncontained way."

A recent review of 79 studies in The Lancet Microbe didn't find any evidence of live virus in people after their ninth day of illness — and viral load also generally peaked in the first week (though viral loads can stay high much longer in immunocompromised people).

Some people can continue to test positive for the virus for many weeks and months after their illness begins, but there's no good evidence that they're necessarily passing it along to others for much longer than the first six days of infection.
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It may also be the case that asymptomatic people (who never show any outward signs of illness) have some of the shortest periods of contagiousness, but researchers aren't sure about that just yet.

It's best for anyone who's been exposed to the virus — no matter how well they might feel — to abide by the seven-to-10-day quarantine timeline and make sure they are not becoming ill before heading back out into the world.
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