Long COVID: Here’s What We Know

5 min read  |  September 22, 2021  | 
Disponible en Español |

As we slog through the second year of a worldwide pandemic, physician-scientists are getting a better view of the long-term effects of the coronavirus. Even so, the persistence of COVID-19 symptoms is proving a challenge for both patients and caregivers.

We now know that these symptoms can last long after a person has tested negative, and some may linger for months, making recovery an uphill climb. This emerging information underscores the need for a better understanding of the persistent consequences of COVID and highlights the complex character of this novel illness.

“Long COVID is one of those things that is hard to define because our understanding of it continues to evolve,” says Olveen Carrasquillo, M.D., M.P.H., chief of General Internal Medicine at the University of Miami Health System. “We don’t really know what exactly causes it, and if you don’t have a handle on that, it’s hard to figure out how to treat it.”

Most people who catch COVID-19 recover within a couple of weeks. But physicians have found themselves caring for a significant number of patients who report lingering symptoms after the initial infection has cleared. For a growing number of people, these symptoms persist for weeks, with no apparent sign of abating.

There is no official definition of long COVID.

In fact, it goes by various names, including post-COVID-19 syndrome and chronic COVID. However, physicians consider a patient to qualify as a long hauler if symptoms persist after four weeks.

Ongoing symptoms after an upper respiratory virus infection are not uncommon, Dr. Carrasquillo says. “We know a cough can last for weeks or months after you’ve recovered from the infection,” he adds, “but with COVID, it’s different. It’s not just the cough that lasts. It’s many other signs and symptoms.”

Patients report a variety of ailments that present with assorted severity. This has led physicians to posit that there may be several types of long COVID, each with different presentations and outcomes — making diagnosing and treating the post-infection illness more difficult.

Moreover, long COVID may be more common than previously believed. Several recent studies have shown that as many as 1 in 3 patients with COVID-19 develop long-term symptoms. And two reports in JAMA calculated that 10% to 30% of COVID patients had at least one persistent symptom up to 6 months after their bodies cleared the virus.

This affected both hospitalized patients and those with milder cases, though not in equal numbers.

Such seemingly contradictory examples can prove confounding. “For a COVID infection, we know who’s at risk, but we don’t have a good sense of who will develop long COVID,” Dr. Carrasquillo says. “We’re still trying to figure that out.”

Little wonder the editors of The Lancet medical journal called long COVID “a modern medical challenge of the first order” in an August editorial.

There is, however, good news as researchers pull back the curtain to reveal compelling details of this enigmatic virus. For instance, a Centers for Disease Control and Prevention study found that fatigue was the most common symptom among confirmed COVID-19 patients who reported long-term complications. This was followed by a prevalence of cough and headaches, shortness of breath, and loss of smell and taste.

Of course, those aren’t the only ongoing symptoms – nor the more serious ones. Many long-haulers complained of brain fog, muscle aches, mobility, anxiety, and depression.

And researchers analyzing Veterans Health Administration data found that every type of kidney problem, including end-stage kidney disease, was more common for COVID survivors admitted to ICUs. The study, published in the Journal of the American Society of Nephrology, suggested that doctors check kidney function in both severe and mild cases, including those who were asymptomatic.

“It’s challenging to develop criteria [for treatment] because there are many more diffused and non-specific generalized symptoms than we usually see after most other virus infections,” Dr. Carrasquillo says.

Though mild and asymptomatic cases can develop chronic COVID, scientists know that sicker people admitted into hospitals are more likely to struggle with persistent symptoms. In a study published online, about half of COVID hospitalized patients suffered from at least one lingering symptom an entire year after discharge. The patients also reported lower scores on quality of life than the general population. Even more worrisome: a few patients in the study said that certain symptoms — namely breathing problems — were worse at the year-mark than at the beginning.

What can people do as scientists tease out answers to the many questions about chronic COVID?

“Get vaccinated,” Dr. Carrasquillo says. “We know vaccines work. We know they prevent severe illness and keep patients out of the hospital.”

Studies continue to prove this. Research published last month in The Lancet Infectious Diseases found that fully vaccinated people – those with two vaccine doses — were 49% less likely to develop long COVID.

They were also 73% less likely than the unvaccinated to be hospitalized and 31% less likely to develop symptoms.

Arming yourself against the virus gives scientists “time to work out a better understanding of what causes these ongoing symptoms,” Dr. Carrasquillo concluded.

Ana Veciana-Suarez, Guest Columnist

Ana is a regular contributor to the University of Miami Health System. She is a renowned journalist and author who has worked at The Miami Herald, The Miami News, and The Palm Beach Post. Visit her website at or follow @AnaVeciana on Twitter.

Tags: covid-19 in Miami, Dr. Olveen Carrasquillo, long covid, public health, pulmonology

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