There Are 4 Subtypes of Long COVID

• A new study has identified four subtypes of long COVID.
• The most common subtypes involve heart and respiratory complications.
• Doctors say splitting long COVID into subtypes may help patients get better treatment.
  

Research has found that long COVID impacts one in five adults under the age of 65, but scientists are still trying to learn more about the condition. Now, a new study has found there are actually four main subtypes of long COVID.

The study, which was published in the journal Nature Medicine, used machine learning to analyze clusters of symptoms in about 35,000 patients with long COVID. (Each patient had at least one lingering symptom after having COVID-19 that lasted between 30 and 180 days after they had the virus.) The researchers used an algorithm that looked at 137 different symptoms, and then classified the patients into four main groups that appeared.

This isn’t the first study to try to classify long COVID. One study published last year divided long COVID symptoms into three clusters—cognitive, respiratory, and everything else.

“There have been quite a few existing studies demonstrating the existence of a broad range of potential long COVID symptoms and signs, but it is still not clear whether they are more likely to co-appear in certain ways or appear individually,” says Fei Wang, Ph.D., co-author of the latest study and assistant professor of healthcare policy and research at Weill Cornell Medicine. “This study aims to fill in this knowledge gap by identifying long COVID sub-phenotypes.”

But what are the different subtypes the researchers found and why does this matter? Here’s what you need to know.

What are the subtypes of long COVID?

The researchers found that long COVID sufferers generally fell into one of the following categories:

• Conditions impacting the cardiac and renal (kidney) systems
• Conditions that impact the respiratory system, sleep, and anxiety problems
• Conditions of the musculoskeletal and nervous systems
• Conditions that impact the digestive and respiratory systems

According to the findings, the subtype impacting cardiac and renal systems was the most common—34% of patients fell into this category. However, 33% of patients fell into the second category, with respiratory symptoms, anxiety, lingering headaches, and insomnia.

After that, 23% of patients fell into the musculoskeletal and nervous systems group, while just 10% of patient had conditions that impacted the gut.

Long COVID symptoms

Research is ongoing into long COVID (also known as post-COVID conditions), but the Centers for Disease Control and Prevention (CDC) has come up with a list of symptoms that the organization has also broken into categories. Those include:

General symptoms

• Fatigue that interferes with daily life
• Symptoms that get worse after physical or mental effort
• Fever

Respiratory and heart symptoms

• Difficulty breathing or shortness of breath
• Cough
• Chest pain
• Heart palpitations

Neurological symptoms

• Brain fog
• Headache
• Sleep problems
• Dizziness when you stand up
• Pins-and-needles feelings
• Change in smell or taste
• Depression or anxiety

Digestive symptoms

Other symptoms

• Joint or muscle pain
• Rash
• Changes in menstrual cycles

The CDC also notes that there are “symptoms that are hard to explain and manage.”

Why does this matter?

The study didn’t necessarily discover anything new about long COVID—it simply categorized data. But long COVID is a broad complication of COVID-19 and that can make it difficult for doctors to accurately identify who may have the condition, as well as how to treat it, says William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine. “This is a nice way to categorize the different long COVID types,” he says. “It will help clinicians understand when their patients come to see them when they may indeed have long COVID, given that there’s no test for it.”

Not everyone with long COVID will fit neatly into a subtype, says Thomas Russo, M.D., professor and chief of infectious disease at the University at Buffalo in New York. However, he says, breaking down this broad illness into different categories can help doctors and researchers find patterns. “Maybe there are some mechanisms or a certain mechanism that is driving a subtype more than another,” he says. If doctors can figure out why patients in certain subtypes are sick, it could lead to better research and eventually treatments for those particular patients, he says.

Will this knowledge help us treat long COVID?

Knowing long COVID subtypes may also “inform future research” on how long COVID works, Dr. Wang says, influencing the development of treatment and public policy.

Dr. Schaffner says that researchers are “heading in the right direction” to try to figure out long COVID. “It’s increasingly diagnosed as the average internist and family doctor becomes more familiar with long COVID and its various presentations,” he says. Many major medical centers have also formed long COVID clinics to try to study why the condition happens, and how to better treat patients. “When you collect patients together, you can study long COVID and figure out better ways to help patients,” Dr. Schaffner says.

If you suspect you may have long COVID, Dr. Schaffner recommends reaching out to your healthcare provider to start. They may be able to refer you to a specialist or send you to a specialty long COVID clinic for help. It’s also a good idea to “closely monitor” the signs and symptoms you have, so you can give your healthcare professional an accurate picture of what’s going on with you, Dr. Wang says.