So... how do we know when symptom free means non-contagious?
March 22, 2020 3:51 PM   Subscribe

There's a lot of great information out there, but I've yet to find guidelines on when someone who has shown symptoms (but has not been tested, as they were mild) might be considered safe to interact with again. My son has shown symptoms ... and they're (thankfully) subsiding. Is there any clear indication of when it is safe to resume contact (he's at his mother's now, I'm at risk, and I miss him). Thanks in advance and hope we're all staying safe.
posted by emmet to Health & Fitness (7 answers total) 8 users marked this as a favorite
Virologist Dr David Ho says in a piece from March 20th:

"After a person recovers from the virus, how long are they still contagious?
That's a very important question. We're not sure; one individual in China was shown to have persistent virus shedding for over a month. But typically, we're looking at a three-week period from onset of symptoms."
posted by needs more cowbell at 3:56 PM on March 22, 2020 [3 favorites]

This suggests that it might typically be safe 10 days after someone first has symptoms. I would wait longer to be sure.
posted by pinochiette at 4:06 PM on March 22, 2020 [1 favorite]

From the CDC:

Time-since-illness-onset and time-since-recovery strategy (non-test-based strategy)*
Persons with COVID-19 who have symptoms and were directed to care for themselves at home may discontinue home isolation under the following conditions:

At least 3 days (72 hours) have passed since recovery defined as resolution of fever without the use of fever-reducing medications and improvement in respiratory symptoms (e.g., cough, shortness of breath); and,
At least 7 days have passed since symptoms first appeared.

posted by insectosaurus at 5:33 PM on March 22, 2020 [3 favorites]

This is one I'd err on the side of caution with. At least add a weekend to the CDC recs.
posted by praemunire at 6:09 PM on March 22, 2020

The European Centre for Disease Prevention and Control has published hospital discharge criteria for confirmed cases.

It includes this interesting point:

"Prolonged virus shedding has been observed among convalescent children after mild infections, in respiratory tract samples (22 days) and faeces (between two weeks and more than one month) [4]. "

The source (reference 4) is a case series of 10 children in areas within China but outside of Wuhan, so it's hard to generalise from this; but at least it's based on data.
posted by lulu68 at 9:14 PM on March 22, 2020 [1 favorite]

We also don't know what percentage of people post-infection are immune to re-infection (thought to be very high) and if you do become immune how long that holds for (totally unknown) or whether you'd be immune to the virus as it mutates (many mutations are being tracking in the wild currently, and being used to trace infections between populations, but all minor so far).

So best to think of this as an evolving area.

The good news is that a LOT of data is being collected and shared. So the best people are accessing a good dataset. They will be able to advise us soon. In the meantime the Next Strain site is absolutely excellent if you're interesting in seeing how the virus is changing.
posted by samworm at 3:53 AM on March 23, 2020

We don't know. That's the only answer right now. Not enough data. We don't know.
posted by juniperesque at 7:00 AM on March 23, 2020

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