Dec. 29, 2021 -- With new cases of COVID-19 skyrocketing to more than 240,000 a day recently in the U.S., many people are facing the same situation: A family member or friend tests positive or was exposed to someone who did, and the holiday gathering, visit, or return to work is just days or hours away. Now what?

New guidance issued Monday by the CDC shortens the recommended isolation and quarantine period for the general population, coming after the agency shortened the isolation period for health care workers.

WebMD reached out to two infectious disease specialists to get answers to questions that are frequently asked in these situations.

If you have tested positive for COVID, what do you do next?

"If you have tested positive, you are infected. At the moment, you are [either] symptomatically infected or pre-symptomatically infected,'' says Paul A. Offit, MD, director of the Vaccine Education Center and a professor of pediatrics at Children's Hospital of Philadelphia. At that point, you need to isolate for 5 days, according to the new CDC guidance. (That period has been shortened from 10 days to 5.)

Isolation means separating the infected person from others. Quarantine refers to things you should do if you’re exposed to the virus or you have a close contact infected with COVID.

Under the new CDC guidelines, after the 5-day isolation, if the infected person then has no symptoms, they can leave isolation and then wear a mask for 5 days.

Those who test positive also need to tell their close contacts they are positive, says Amesh Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security.

According to the CDC, the change to a shortened quarantine time is motivated by science ''demonstrating that the majority of SARS-CoV-2 transmission occurs early in the course of the illness, generally in the 1-2 days prior to onset of symptoms and the 2-3 days after."

If you have been exposed to someone with COVID, what do you do next?

"If they are vaccinated and boosted, the guidance says there is no need to quarantine," Adalja says. But the CDC guidance does recommend these people wear a well-fitting mask at all times when around others for 10 days after exposure.

For everyone else, including the unvaccinated and those who are more than 6 months out from their second Pfizer or Moderna vaccine dose, or more than 2 months from their J&J dose, the CDC recommends a quarantine for 5 days -- and wearing a mask for the 5 days after that.

On a practical level, Adalja says he thinks those who are vaccinated but not boosted could also skip the quarantine and wear a mask for 10 days. Offit agrees. Because many people exposed have trouble quarantining, Offit advises those exposed who can't follow that guidance to be sure to wear a mask for 10 days when indoors. The CDC guidance also offers that as another strategy -- that if a 5-day quarantine is not feasible, the exposed person should wear a mask for 10 days when around others.

But if someone who was exposed gets symptoms, they then enter the infected category and follow that guidance, Offit says.

When should the person who has been exposed get tested?

After the exposure, ''you should probably wait 2-3 days," Offit says. "The virus has to reproduce itself."

Testing should be done by those exposed at least once, Adalja says.

"But there's data to support daily testing to guide their activities, but this is not CDC guidance. Home tests are sufficient for this purpose."

At what point can the infected person mingle safely with others?

"Technically, if asymptomatic, 10 days without a mask, 5 days with a mask," says Adalja. "I think this could also be guided with home test negativity being a gauge [as to whether to mingle]."

Show Sources

CDC: "CDC Updates and Shortens Recommended Isolation and Quarantine Period for General Population."

Paul A. Offit, MD, director, Vaccine Education Center, and professor of pediatrics, Children's Hospital of Philadelphia.

Amesh Adalja, MD, senior scholar, Johns Hopkins Center for Health Security, Baltimore.

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