Coronavirus FAQ: Remind me, what's the difference between isolation and quarantine?

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I see that the CDC has set new guidelines for isolation and quarantine. Can you explain what those two terms mean exactly? And also, can you review the guidelines?

Those two pandemic-related terms were in the headlines this week as the Centers for Disease Control and Prevention updated its guidance about what to do if exposed to or stricken with COVID – basically shortening the number of days you should keep to yourself.

So why are there two terms – and what do they mean exactly?

Okay, let's go to the CDC dictionary.

According to the CDC, isolation refers to what you should do when you suspect or confirm that you have COVID-19 even if you don't have symptoms. Here are the steps to take:

• Monitor your symptoms. If you have a symptom that warns of a potentially severe case, such as trouble breathing, seek medical care immediately.
• Stay in a separate room from other household members, if possible.
• Use a separate bathroom, if possible.
• Avoid contact with other members of the household and pets, who can also get COVID-19.
• Don't share personal household items, like cups, towels and utensils.
• Wear a mask when around other people if able.

Quarantine refers to staying away from others after being exposed to someone with COVID-19 when you don't know whether you've been infected or not. The current definition of exposure: being in contact with that COVID-stricken person for more than a total of 15 minutes in a single day and at a distance of 6 feet or less, although it is possible that the nature of the omicron variant could lead to changes in that definition).

You don't have to barricade yourself in your room as you would if you test positive for COVID but you should wear a mask around others in your household and stay away from those housemates, especially if they're at higher risk of getting very sick from COVID-19, according to the CDC.

Watch for fever (100.4◦F or higher), cough, shortness of breath or other symptoms of COVID-19. And if you develop symptoms, immediately head to the isolation rules (see above).

Now that we've clarified the terminology, let's review the changes that CDC made in deference to the highly transmissible omicron variant,

Isolation

After five days, if you're asymptomatic or your symptoms have largely resolved (no fever for 24 hours per CDC), you can end isolation so long as you continue to wear a mask around others, even in your home, for an additional five days.

Quarantine

Vaccinated with Pfizer or Moderna within the last six months? Vaccinated with Johnson & Johnson within the last two months? Boosted? If any of these conditions apply to you, then no need for a precautionary quarantine after an exposure to COVID. However, CDC wants you to wear a mask for 10 days following the exposure and recommends a COVID test on day 5.

Watch for fever above 100.4, cough, shortness of breath or other symptoms of COVID-19 — and if they occur, isolate and pursue a test to see if you have COVID. If yes, the isolation rules above kick in.

But if you don't fall into any of those vaccination or booster categories, quarantine does apply per the new CDC rules. You should quarantine for five days following your exposure. After five days, you should get tested, if you can, and continue masking around others through day 10.

"The vast majority of viral transmission happens in those first five days, somewhere in the 85 to 90% range," said CDC director Dr. Rochelle Walensky. But you could be infectious up to ten days, generally the upper limit, so a ten- day mask regimen can protect others you come in contact with, explains Dr. Abraar Karan, an infectious disease fellow at Stanford. He also advocates using a high-filtration mask if possible, like an N95 or KN95

If you can't quarantine because, say, your family's income depends on your going to work or you have roommates in a small apartment, "it's really important that you wear a mask at all times around others for 10 days after your exposure and get a test at day 5," says Walensky. "And if you develop symptoms of COVID-19 during your quarantine period or your 10 days after exposure, you should get a test and isolate until your test results return. Then isolate if you get a positive result."

But there are criticisms of this new guidance.

"While new CDC isolation guidelines are reasonable, here's what I would have done differently," tweeted Dr. Ashish Jha, dean of the Brown University School of Public Health. "1. Required a neg[ative] antigen test after 5 days [to end isolation]. 2. Had different guidelines for vaccinated (contagious for shorter time) versus unvaccinated. 3.Specified higher quality masks.

"I think it's really important for people to understand that the CDC guidelines were issued out of necessity," says Dr. Leana Wen, research professor of health policy and management at George Washington University in Washington, DC and former Baltimore health commissioner. "We are facing the possibility of the US surpassing more than one million COVID cases every single day," says Wen. "At that level we would not be able to sustain our critical infrastructure and the CDC issued the guidelines to keep our society functioning."

"That doesn't mean, though," says Wen, "that five days of isolation is ideal, so if someone has been diagnosed with COVID-19 and they are, for example, planning to visit an older person in a nursing home, my recommendation is that they isolate until they are able to get a negative test if it's within ten days, or wait ten days [from testing positive]."

Of course, all of the testing advice depends on the availability of tests – a topic we covered here.

Fran Kritz is a health policy reporter based in Washington, D.C., who has contributed to The Washington Post and Kaiser Health News. Find her on Twitter: @fkritz

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