What is long Covid?

Everyone has undoubtedly heard plenty about Covid-19 over the past four years, but there's one big question many people are still asking: What is long Covid?

Long Covid is an illness that develops after a person has been infected with SARS-Cov-2, the virus that causes Covid. An estimated 400 million people around the globe have been diagnosed with the condition since 2020 (a number that’s likely an undercount), according to a study published on August 9 in the journal Nature Medicine. The researchers also projected the disease will have a roughly $1 trillion annual economic impact globally due to the cost of treatment, financial burden on system supports such as disability benefits, and negative impact the disease has had on key labor market indicators like productivity.

In case you’re not sure what long Covid is, how it’s diagnosed and treated, or how long it lasts, Healthcare Brew has put together an explainer for you.

What is long Covid?

The National Academies of Sciences, Engineering, and Medicine, which advises the US government on science and technology issues, issued a definition of long Covid in June 2024 that has been adopted by organizations like the World Health Organization. It classifies the condition as “an infection-associated chronic condition that occurs after SARS-CoV-2 infection and is present for at least three months as a continuous, relapsing, and remitting, or progressive disease state that affects one or more organ systems.”

According to M. Aruna Lochan, a nurse practitioner at the Cleveland Clinic, the condition can come with a variety of symptoms that affect different parts of the body, including the heart, lungs, and brain.

How is long Covid diagnosed?

Since the definition of long Covid is still relatively vague, diagnosing it can be tricky, experts say. There’s neither a definitive lab test to determine if a patient has the disease nor a specific set of symptoms that leads to a diagnosis.

Instead, according to Lochan, physicians look at factors such as when the patient first became ill, if they tested for Covid-19 when their symptoms began, and how long their symptoms have been present.

What are common long Covid symptoms?

There are a wide array of symptoms that fall under the long Covid umbrella—in fact, the CDC says more than 200 have been identified.

But some common themes do emerge. Lochan said some of the most common symptoms she has heard from patients include respiratory symptoms like shortness of breath, coughing, and chest discomfort, as well as neurological issues like brain fog and having trouble concentrating.

Nisha Viswanathan, an assistant professor of medicine at the University of California, Los Angeles (UCLA), said some of the most common symptoms she has seen include fatigue, chest pain, and heart palpitations.

However, less common symptoms, such as sleep issues and hair loss, may also indicate long Covid, according to Nebraska Medicine.

While research is still inconclusive, a team at Yale Medicine has theorized that long Covid could even trigger autoimmune diseases, such as lupus or rheumatoid arthritis.

How do you treat long Covid?

Because there are so many long Covid symptoms and each patient presents differently, treatments for the condition vary widely according to “what their primary concerns that they want addressed are,” Lochan said.

Viswanathan, who is also an internal medicine physician and co-director at UCLA’s long Covid clinic, said some common treatments include physical therapy and medications to manage symptoms.

“It’s not a one-size-fits-all approach,” she said. “It really depends on: What are the symptoms you’re struggling with? How severe are they? How are they impacting your life?”

For instance, if a patient’s primary concern is respiratory symptoms, Lochan said, physicians may screen them for conditions like asthma or chronic obstructive pulmonary disease and treat them based on the results.

But how long does long Covid last?

Just as there is a range of treatments for long Covid, the duration of the disease differs from patient to patient.

Some patients recover within a few months of being diagnosed with long Covid, Lochan said, while others are still dealing with symptoms four years later.

Viswanathan said some patients may go into remission only to see their symptoms triggered again by another viral illness, such as a cold.

If long Covid behaves like other infection-associated chronic illnesses, such as myalgic encephalomyelitis/chronic fatigue syndrome, some patients may have symptoms for the rest of their lives, according to Stephanie Grach, a general internal medicine specialist at the Mayo Clinic in Rochester, Minnesota.

Do Covid boosters help reduce the risk of long Covid?

A solid defense against facing lifelong symptoms could be Covid booster shots.

There is some data to suggest that vaccines and boosters reduce the risk of contracting long Covid, Grach said. A study published in March 2024 in medical journal The Lancet, for example, showed that being vaccinated reduced the risk of developing long Covid by 52%.

But Covid booster uptake has been minimal: As of May 2024, just 22.5% of US adults reported they had received an updated vaccine after September 2023, according to CDC figures.

There are also ongoing studies to determine if Covid treatments like Pfizer’s Paxlovid antiviral pill may help treat or reduce the risk of long Covid, though a June 2024 study from Stanford found that a 15-day course of Paxlovid didn’t seem to help long Covid patients.

In general, Viswanathan thinks the data on whether boosters can help reduce long Covid symptoms is still inconclusive.

“There have been some studies that said perhaps it does; there have been other studies that say perhaps it does not,” she said. “I don’t think we can say conclusively yet that it’s an actual treatment option for long Covid.”

What’s happening next

Overall, there are still many unknowns when it comes to long Covid, and researchers are doubling down to find answers. to find answers.

For instance, since 2021, the National Institutes of Health (NIH) has been conducting what it’s calling the Recover Initiative to “fully understand, diagnose, and treat long Covid.” The trials include nearly 90,000 people at 300 research sites across the US, and the program has received just north of $1.5 billion in government funding. In February, the NIH shared in a press release that it will invest an additional $515 million over the next four years for continued long Covid research.

Specifically, researchers hope the Recover Initiative will help them understand how exactly the virus that causes Covid affects each part of the body, which treatments could be effective to treat long Covid, and why some people seem to recover fully from the condition while others do not.

“There are a lot of studies and a lot of research going on in this area,” Viswanathan said. “Ultimately, I think that we are learning quite a bit, especially in the last year.”