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Sometimes it seems like every article about the coronavirus is trying to scare you.

That’s especially true for articles about the long-term impacts of COVID-19. They tend to start the same way: introducing you to someone whose life was terrific before the virus and terrible now, due to some unexpected remaining symptom. There’s a transition sentence — “But Chad isn’t alone” — telling you that other people have this happen to them too. Doctors are interviewed about how likely this is, studies are referenced to the degree possible. Finally, the article returns to Chad, who just wishes he hadn’t gone to that get-together where he caught the virus in the first place.

Stories like this grab your attention, then fill in the details. But I think sometimes they can lack context, too. If we zoom in on one tree, we can miss some pretty important facts about the forest.

So how do we describe what we know about the forest? I found the format of a Reddit post really helpful, which riffed off of something then Defense Secretary Donald Rumsfeld once said. We can split up the forest into known knowns, known unknowns, and unknown unknowns.

Known knowns are the things we know about the forest through careful observation and study.

Known unknowns are the things we know we need to learn more about the forest. A cloud might be covering an overhead view, so we need to send an explorer over there to find out what’s going on.

Unknown unknowns are the things that might happen that we aren’t even considering. A giant meteor might strike. That’d change our opinion of the forest pretty drastically.

Just over six months since we discovered the coronavirus, we can use that same approach to discussing where we are in terms of discovering its long-term impacts.

Known knowns

We know how long people’s coronavirus symptoms normally last. The COVID Symptom Study is a joint project from researchers at King’s College of London and Massachusetts General Hospital. Essentially, they developed an app that asks those with COVID to take one minute every day to describe the symptoms they’re facing. They’ve had a huge response rate: 3,984,380 contributors so far.

Data from the COVID Symptom Study. (https://covid.joinzoe.com/post/covid-long-term)

The study found that most people do recover completely within 14 days, although even that is a relatively long time for most people when they think about recovering from a disease. But there’s also this long tail for people who seem to have symptoms for 25, 30, 35, or 40 days, perhaps longer. They conclude that about one in 10 people still have symptoms after three weeks. This is the “long COVID” group.

What kind of symptoms are these? They range from mild to severe.

Sense of smell. You probably know that coronavirus tends to make people lose their sense of smell for a while; various studies have estimated the percentage of coronavirus patients that lose smell to be anywhere from 30% to 98%. In Salt Lake County, 38% of cases have reported loss of smell.

An Italian study checked in on 202 patients who lost their smell to see how long it lasted. Four weeks from when the symptoms started, 49% reported complete resolution, 41% reported an improvement in the severity, and 10% reported that their smell was unchanged or worse. Interestingly, there wasn’t any correlation between how long these people lost their sense of smell and how long they had other COVID-19 symptoms.

Post intensive care syndrome. Up to 75 percent of people who become critically ill and stay at an ICU develop this. It includes neurological, physical, and psychological symptoms.

Blood clot issues. Remember, some of what hurts people isn’t the virus itself, but the body’s immune response to it. In particular, one quirk of the immune response is that it can create inflammation in some places in the body and blood clots in others. Blood clots can cause all sorts of problems everywhere in the body with COVID-19, from kidney failure to limb amputation.

Lung damage. People who have pneumonia or need to go on a ventilator often have long-term lung scarring as a result. The elderly are more likely to experience scarring, but whoever experiences it does see diminished lung capacity and exercise capacity. In addition, the blood clots can cut off circulation in the lungs: studies have found that 23% to 30% of those with severe COVID-19 have this occur. That also creates long-term impacts on lung function.

Strokes. If one of those blood clots causes a stroke, that obviously has long-term impact. Stokes have been seen in both young and old due to coronavirus. Young people don’t die that frequently, but they are permanently effected: studies have found between 42% and 53% of young stroke victims are able to return to work.

Known unknowns

Because we’ve only known about coronavirus for such a short period of time, there’s much we want to know more about, but just haven’t had the time to figure it out yet. The National Institutes of Health is creating the CORAL study, which will take a look at the long-term health of 3,000 coronavirus patients. Countries all over the world are doing the same thing. Here are some of the questions those studies are trying to figure out.

Who gets long-term symptoms and why? You’d expect that it was people who faced severe symptoms that lasted longer: the taller the mountain, the longer it takes to get up and down it, right? But according to the COVID Symptom Study researchers, “people with mild cases of the disease are more likely to have a variety of strange symptoms that come and go over a more extended period.”

Why is that? One hypothesis is that those who are hospitalized receive medication to prevent the blood clotting and inflammation issues that can cause some of the unexpected symptoms, but we don’t know if that is true. Of course, that doesn’t explain the number of hospitalized people who get unexpected symptoms anyway.

How permanent is most lung damage? We know that severe lung damage is known to have long-term effects, but what about mild lung damage? For example, one study looked at 58 people who had tested positive who were completely asymptomatic — except they had visible lung damage on their CT scans. When doctors look for lung damage, they’re looking for translucent spots.

A CT scan of a lung of an asymptomatic COVID-19 positive case. The translucent blob where the arrow points is called a "ground-glass opacity," indicative of lung damage. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7152865/)

Every study participant had literal pneumonia, but only 16 of the 58 people ever showed symptoms from the disease; 22 of the 58 showed complete repair after a week; and 21 showed at least visible improvement in their lungs. Most of the time, the body repairs itself relatively quickly. But what happens to those with medium-severity lung damage?

A study of hospital patients in the original SARS outbreak found that even young people who avoided the ICU had problems. In particular, when patients who had SARS were asked to walk normally for six minutes, they walked significantly shorter distances than people who hadn’t had SARS. But given what we know about comorbidities, it’s possible that being hospitalized was enough to lower these people’s walk distance even before SARS. What’s really going on here?

Is COVID-19 really triggering diabetes in people? We know that diabetes is a preexisting condition that tends to make COVID-19 worse. But there are a growing number of cases in which diabetes is seemingly being triggered by the virus, even mild cases. That sounds crazy, but there are a number of viruses that have shown the ability to do that before, including H1N1. How often does this happen? Does this form of diabetes stay around, or do people get better? Who is at risk?

What in the world is going on in people’s brains? Somewhere between two-thirds and three-quarters of people who go to ICUs as a result of COVID-19 end up facing delirium — which may be related to that post-intensive-care syndrome mentioned above. But ICU doctors are seeing symptoms which go above and beyond typical ICU problems: repeated headache, confusion, seizures they aren’t use to seeing at that frequency.

People who aren’t in ICUs, with even mild coronavirus, are also experiencing weird mental symptoms. Is this just because their brains are getting less oxygen? Will it get better? It clearly does in some people, but others are still experiencing effects from a disease that started months ago. Some doctors worry that the virus can break the barrier between blood and brain cells; if true, that’s uniquely bad.

What long-term impact does coronavirus have on the immune system? Studies say people who were infected still have wild immune cell numbers four to 11 weeks after recovery — a number limited only by how much time the study had.

“There are some people where lots of really important cells are completely depleted and disappeared from the blood. And there are other people, perhaps people who were more mildly affected, where all the cells look terribly turned on and terribly aggressive and terribly activated,” Danny Altmann, a professor of immunology at Imperial College London, said on a Guardian podcast.

Are the high levels why many mild cases experience long-term fatigue? How much longer is the immune system out of wack? What consequences do these levels of immune system cells have on other infection? We have to start figuring that out.

Unknown unknowns

I think some of the scariest coronavirus articles have focused on some really unlikely possibilities. For example, some have worried about how the virus, like chicken pox or herpes, stays in your body your whole life. That it could result in symptoms decades later. There’s no evidence that coronaviruses of any sort do that, so it’d be pretty illogical if this one did.

Likewise, some are worried about the disease mutating into something more severe. Viral mutations happen all the time, but typically they move in the direction of less deadly rather than more deadly. Viruses want to infect as many hosts as possible, and dead bodies are terrible at going to bars and restaurants and spreading the disease.

It’s just not worth it to spend your whole life worrying about the really unlikely stuff. There’s plenty of real worries above without having to get into sci-fi territory.

We tend to put cases in two buckets — people who die or people who will recover. Heck, the state of Utah explicitly does that: they just add anyone who hasn’t died within three weeks of their positive test to the “recovered” tally in their official stats every day. Long-term impacts, those 10% of cases that last longer, muddy that clean split. “Recovered” doesn’t mean “100%.”

As a relatively young and healthy person, I’m very unlikely to die from the virus. But I don’t want my ongoing quality of life to be hurt, either. I want to be able to play soccer and tennis when all of this is over, and hopefully just as well. It’d be terrific if my brain was at 100%, and if I had my full array of immune system functions.

It’s just another thing to consider before engaging in risky behavior. Do I live my life in fear? No. But am I taking basic precautions everywhere I go? Absolutely.

Andy Larsen is a Tribune sports reporter who covers the Utah Jazz. During this crisis, he has been assigned to dig into the numbers surrounding the coronavirus. You can reach Andy at alarsen@sltrib.com or on Twitter at @andyblarsen.