Can Coronavirus be Diagnosed After the Illness?
March 11, 2020 8:47 PM   Subscribe

A family member had a flu-like illness about a month ago that sounds a lot like the symptoms of coronavirus:

They had a 102.5 fever for several days along with cough, weakness/tiredness and some muscle aches. Then their fever dropped to 99.5 and remained for more than two weeks. All symptoms except the muscle weakness abated during that time. Family member reluctantly stayed home until their temperature returned to normal.

Should they be tested for coronavirus? Would the test even register positive after the symptoms and fever abate?
posted by summerstorm to Health & Fitness (9 answers total) 4 users marked this as a favorite
Science had a relevant story on Feb. 27: "Singapore claims first use of antibody test to track coronavirus infections": "Researchers around the world are racing to develop antibody tests, also called serological tests, that can confirm whether someone was infected even after their immune system has cleared the virus that causes COVID-19. The group that developed the test, at Duke-NUS Medical School in Singapore, is among the front-runners, although its assay has to be validated before it is taken into production and deployed widely."
posted by Wobbuffet at 8:52 PM on March 11, 2020 [3 favorites]

Following up on that, the coronavirus serology test for antibodies absolutely could tell you whether had coronavirus after the infection.

The current number of tests available is (by reports I've seen) exceedingly small and your family member probably wouldn't get a test if they asked for it. AFAIK the only reason for the test would be for public health reasons; I don't believe there's any special followup treatment that would benefit them.
posted by mark k at 8:56 PM on March 11, 2020 [5 favorites]

Where is the family member?
posted by theora55 at 9:25 PM on March 11, 2020

Here is a summary of a serological test conducted in Guangdong after the SARS coronavirus outbreak in 2003. They used the study to work out how many of the animal market workers had resistance (about 9% but higher among those who worked with animals like civets). Those kinds of serological studies of antibody prevalence in a population are very important to understand how the virus originated and how many people got it but showed no or light symptoms. You can't really do them properly until an outbreak is over. I expect we'll see similar studies from Wuhan before too long.

Researchers will also be interested in how infectious somebody who has had the virus remains - and for how long. But they have a large supply of people who have tested positive to work with on that question.

Regarding your family member: A month on from the infection, without a positive test to confirm it was coronovirus - and with the possibility that a molecular test (to look for current infections) would now come back negative anyway - it is a tricky. 14 day self-isolation of anybody who has been in close contact with the family member would probably be wisest move.
posted by rongorongo at 11:45 PM on March 11, 2020 [1 favorite]

I am an epidemiologist; I am not your epidemiologist. I am not a subject matter expert in coronaviruses, but I do have exeperience with outbreaks and serosurveys (basically, you walk around getting blood tests from everyone to estimate how big an outbreak actually was).

Can Coronavirus be Diagnosed After the Illness? Would the test even register positive after the symptoms and fever abate?
Probably, at some point. I know more about flaviviruses (dengue, Zika, chikungunkya) and we are able to use IgM/IgG testing, which remains positive for months or years after the illness. Right now, we don't know how long SARS-CoV-2 (electric boogaloo) will show up in blood. It is not a current priority to determine this. As rongorongo said, serosurveys are common and will be vital for understanding the true scope of this outbreak, but they aren't, in my experience, conducted during the widespread transmission phase.

Should they be tested for coronavirus?
Nope. In the US (assuming you are in the US), there is no rationale for testing someone based on previous symptoms. It would be a waste of a test. They should proceed as if they had COVID and everyone around them should act as if they have been exposed.
posted by quadrilaterals at 7:06 AM on March 12, 2020 [5 favorites]

Sorry -- to be clear, when I say "everyone around them", I mean people in close contact, by which I mean people who shared a living space, meals, or cared for that person. If there are non-family members included in that definition, you should alert them. And when I say "act as if they have been exposed", I mean self-monitoring (taking temperature; avoiding vulnerable populations, large groups, and congregate settings; etc.) for two weeks.
posted by quadrilaterals at 7:09 AM on March 12, 2020 [1 favorite]

Best answer: It's a shame there is no serological test easily available.

There are now hordes of people (I would include myself in this) who've recovered from some kind of flu virus in the last few weeks, but they don't know if it was COVID-19 or just the common flu. If it was COVID-19, they are now immune and (I think) non infectious, the ideal people to go outside and help others, but without a test nobody knows if they are in that category.
posted by w0mbat at 12:13 PM on March 12, 2020 [4 favorites]

There’s evidence that people who have recovered can still shed virus for up to 37 days. Median 20 days, so I’d be very cautious about going back out to volunteer to vulnerable populations.
posted by radagast at 9:48 AM on March 13, 2020

There’s evidence that people who have recovered can still shed virus for up to 37 days.

This is a misreading of the study. The evidence is that they can shed virus for a total of 37 days from time of onset. When they say that "survivors can shed for X days" they do not mean that they are counting from the time the person officially became a survivor.
posted by stefanie at 8:23 AM on March 14, 2020 [1 favorite]

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