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Are COVID-19 symptoms changing, and when are you contagious?
We're learning more about this virus and disease all the time. But here's where the research currently stands.
Welcome to Not a Doctor, the only (free!) newsletter about health and science that prizes a functioning thermometer above all other devices.
I’m Melody Schreiber, a journalist and the editor of What We Didn’t Expect (Nov. 2020). I’m not a doctor, or a scientist, or really an expert of any kind. I just like to ask questions and try to find the answers to them.
Today, we’re talking about the symptoms and spread of the coronavirus — whether symptoms are changing, how many people are asymptomatic, how long you’re contagious for, and more.
Please keep in mind: researchers and the public are constantly learning about this virus, and the answers to these questions will definitely evolve as more research is done.
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What are the symptoms?
You probably already know the three main symptoms of COVID-19: fever, dry coughing, or shortness of breath.
There’s also tiredness, aches and pains, or a sore throat, and some people also have diarrhea, nausea, or a runny nose.
You might have some, all, or none of these symptoms. (That’s why I say “or.”) And you might have others that aren’t documented as part of the illness yet.
Several people have also reported the temporary loss of smell and taste; that’s not an official symptom yet, but there does seem to be a relationship there for some people. Others have also reported headaches and stomach pain.
In the United States, where testing is extremely limited and hospitals are becoming strained, the CDC recommends seeking medical attention when you have trouble breathing, persistent pain or pressure in the chest, bluish lips or face, more confusion than usual, or you’re losing consciousness.
I’ve found this Twitter thread very useful: when you can’t walk across the room or hold a conversation, it may be time to call the doctor and head to the hospital.
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Are symptoms changing?
There are some symptoms that aren’t part of the official WHO and CDC symptom list, like losing your sense of smell.
But that doesn’t mean the virus is changing; it means we’re getting better at detecting symptoms that otherwise might have gone under the radar, especially in mild cases that wouldn’t have been seen at a hospital before.
There’s also some interesting research on what kind of respiratory infection this is. Originally, COVID-19 was seen as a lower respiratory infection (in the lungs and anything below the voicebox).
But some researchers think it could also be an upper respiratory infection (from the sinuses down to your throat) as well. It’s even possible that an infection that starts off in the sinuses could move down to the lungs.
Although the research is far from clear on this, I strongly recommend that you stay home even if you’re just feeling a little sniffly and swear to God it’s not COVID. And, of course, consult with your doctor any time you’re ill.
Photo: Brian Hart/Flickr
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How soon after exposure to the virus do symptoms develop?
According to this study, people start showing symptoms 2 to 14 days after exposure. The median time is 5 days, and most (97.5 percent) develop symptoms within 11 days.
It's not clear how many people develop no symptoms at all (asymptomatic cases). One study on China showed that 86 percent of people who had the virus were either asymptomatic or had extremely mild cases. (Those are two very different things, which makes that study a bit frustrating.)
In Italy, about 60 percent of those who tested positive for SARS-CoV-2 had no symptoms at all.
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If you’re asymptomatic, are you still contagious?
The million-dollar question (or one of them, at least). The study on China found that asymptomatic and mildly symptomatic people were about half as contagious as people with symptoms. That makes some obvious sense — if you’re coughing more, you’re more likely to be spreading the virus through the air.
BUT the study also found that asymptomatic and mildly symptomatic people were responsible for about 79 percent of the virus’s spread. That’s because they didn’t realize they were sick, and so they took fewer precautions.
Also, coughing isn’t only the way to spread the virus — you might touch your mouth and then touch something else, thus spreading the germs. And it’s possible the virus is also spread by breathing.
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When are you contagious?
People seem to become contagious about two days before they start showing symptoms (if they ever do).
But one preprint study — preprint means it hasn’t been peer-reviewed or accepted for publication yet, so all results and conclusions need to be taken with a hefty grain of salt — found that your viral load can be highest right before you get sick. That could mean you’re most contagious before you know you’re even sick.
More research definitely needs to be done on this!
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When will you test positive for the virus if you have it?
You can test positive for the virus as long as it’s circulating in your body. That could be a day or two before you start showing symptoms up until a few days or even weeks after you’ve recovered.
In China, there are some people who recovered from the virus and had tested negative. Now, they’ve tested positive again.
It could be that their test is inaccurate, or it could be that the virus “hides” from the test, which would mean they need several negative tests over a period of time to know that the virus is truly vanquished.
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When do you stop being contagious?
Another million-dollar question. It's not exactly clear how long you can be contagious for.
If you’re confirmed to be sick with COVID-19, the CDC recommends staying in isolation until your coughing and shortness of breath improves, you have no fever (and haven’t been taking Tylenol to reduce your fever), and you’ve had two negative tests taken at least 24 hours apart.
If you think you’ve had it but weren’t able to get a test, the CDC recommends staying in isolation until at least seven days after your symptoms first appeared and three days (72 hours) after your symptoms go away.
To go back to China: the people who seemed to recover and then tested positive aren’t necessarily contagious. Just because the virus is still hiding out in their cells doesn’t mean they’re giving it to others.
But this is the kind of question that can only be determined with more research — and more time.
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Can you get the virus again?
This is another question to which we can’t really know the answer — not yet.
Immunity really depends on the virus. With some, you have to fight them off once and then you have immunity for a long time; with others, you have to keep fighting them off every year or so.
This virus has only existed in humans for a few months now. There’s still a lot we can’t know, including how long we’re immune and what the virus means for our health in the long-term.
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