Doctors Explain The Current Theories On Why COVID Cases Can Last So Long

As you're likely aware by now, having COVID isn't like your typical cold where you expect to stay in bed for a few days, then go back to work like it's nothing. It can knock you flat for weeks, or have symptoms that linger long after you test negative again. Researchers are starting to come up with theories for why some COVID cases last so long. Up to 87% of people continue to experience a few symptoms over a month after their COVID infection, according to an Italian study published in JAMA in July. For some, COVID symptoms stick around for the long haul, months after their first worrying cough or loss of smell. For others, COVID symptoms come and go, even once they feel they've recovered.

"There's emerging evidence that some people who have the COVID infection have lingering symptoms for a long time, much longer than people would expect," Dr. Tae Chung M.D., assistant professor of physical medicine and rehabilitation at Johns Hopkins Medicine, tells Bustle.

The average time between catching COVID and showing symptoms is around three to 14 days, according to Harvard Health, and Johns Hopkins Health says those symptoms usually last about one to two weeks in mild cases. From beginning to end, many people will be riding the COVID train for three weeks to a month — but others are bedbound for ages, or feel better only to be floored by recurring symptoms, an experience called "long haul" COVID. When it comes to understanding why COVID symptoms decide to stick around, doctors are just beginning to make inroads.

Why A COVID Case Can Last So Long

There are a few theories on why some COVID cases can cause someone to feel ill for weeks, or even months. Generally speaking, mild COVID symptoms can vary a lot from person to person — so while your roommate may be up and kicking a few days after a positive diagnosis, your COVID experience might drag on for ages. The World Health Organization reported in September that many people, even those with mild illness, experience "lingering" symptoms and a prolonged recovery, where they're no longer infectious but still feel terrible.

If you've got a bad case of COVID, your recovery may take six weeks or more, says Johns Hopkins Health. Nature reported in September that people who'd had severe COVID could experience long-term damage to lungs and other organs. But even if you have a mild case, your symptoms might drag on. A study published in PLoS One in November found that persistent fatigue, where you feel unable to even get out of bed, is really common among people who've come through COVID, occurring in about 52% of people — and it's completely unrelated to how severe their original infection was.

It's not clear why some people get mild COVID symptoms that clear up like a cloud on a nice day, and others feel rotten for weeks. A study of people with mild to moderate COVID infections published in Clinical Microbiology & Infection in October found that up to 60% of cases still had symptoms two months after they'd first caught it. The authors suggested this could have something to do with inflammatory response. Inflammation is the body's reaction to injuries and threats, so if your body reacted to your COVID infection with a massive inflammation flare-up, it could take a while for symptoms to die down.

"This is actually emerging as a very serious health issue," Dr. Chung says. "It can be very debilitating."

COVID Long-Hauler Researchers Have A Lot of Questions

Long-haul COVID, where symptoms continue to pop up months after your first infection and recovery, is another issue. Nature reported in September that it's possible that some people might experience high inflammation levels for months after their COVID diagnosis, and that may lead to long-term symptoms, or damage their immune systems over time. But there's not enough information yet to confirm this.

There are many theories about long COVID. "When you listen to their symptoms carefully, it sounds very much like POTS, or postural orthostatic tachycardia syndrome," Dr. Chung says. "There's a suspicion that long-haulers may have POTS or some other kind of autonomic dysfunction." POTS is a blood circulation disorder that causes dizziness and an abnormal heart rate, and it's often diagnosed after a viral illness. It's also more common in women than men.

Dr. John Sellick D.O., professor of medicine at the Jacobs School Of Medicine & Biomedical Sciences at the University of Buffalo, says that many doctors believe long COVID might be the result of an overactive immune response, but that's not confirmed. "The one thing that is clear is that infectious virus is no longer present, so there is no specific antiviral treatment to be given."

COVID may also linger in "pockets" in your body long after the bulk of it has been kicked out by your immune system, the BBC reported in October. A study published in Nature Neuroscience in December found that the coronavirus's spike proteins — the little barbs on its surface — help it to get into the brain. If it hangs around there, even in small amounts, it can cause long-term issues like brain fog, as well as interfering with the brain's respiratory centers, which help control breathing. A study published in The Lancet in August found that some people with COVID actually show changes in the structures of their brains, which could explain why some symptoms carry on for so long.

There are now calls for in-depth studies of long COVID to help doctors understand why the symptoms stick around for so long in some people, and what can be done to help. Patient-Led Research for COVID-19 is conducting a survey of other COVID patients, while a clinic has opened at UC Davis specifically to research the condition. Many survivors of long COVID have banded together in support groups worldwide, but they'll likely be waiting a while for definitive answers about what's really going on.

Experts:

Dr. Tae Chung M.D.

Dr. John Sellick D.O.

Studies cited:

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