What Are the Top Symptoms of Long COVID?

Although vaccinations, treatments, and immunity from previous infection have significantly reduced the number of people who get severely ill with COVID-19, long COVID is not going away. By some estimates, lingering symptoms of the virus affect 65 million people worldwide.

An ambitious new scientific investigation published in JAMA on May 25 proposed a list of 12 symptoms that can be used to identify long COVID. Researchers consider it a big first step in the quest to find treatment or even a cure for the condition.

The report is among the first wave of published studies from the ongoing $1.2 billion National Institute of Health (NIH) RECOVER trial. The study’s principal goal was to develop an approach to identify people with long COVID based on symptoms — and to do it in a data-driven way, says co-lead author Andrea Foulkes, ScD, the director of biostatistics at Massachusetts General Hospital and professor of medicine at Harvard Medical School in Boston.

“We identified 12 symptoms that set apart people with and without a history of infection,” Dr. Foulkes says.

The study found the following were the 12 most common symptoms of long COVID:

Post-exertional malaise (the worsening of symptoms following even minor physical or mental activity)
Fatigue
Brain fog
Dizziness
Gastrointestinal symptoms
Heart palpitations
Issues with sexual desire or capacity
Loss of smell or taste
Thirst
Chronic cough
Chest pain
Abnormal movements

“Importantly, people with long COVID may have many additional symptoms that correlate with these 12,” says Foulkes.

Study Findings Match What Doctors Are Seeing in Long COVID Clinics

“We have all been really excited for the initial results of this study,” says Jessica Bender, MD, MPH, an internal medicine physician and co-medical director at the University of Washington’s Post-COVID-19 Rehabilitation and Recovery Clinic at UW Medicine in Seattle. UW Medicine was among over 200 clinical sites that contributed to the investigation, so a few of Dr. Bender’s colleagues were involved in the study. (She was not.)

These symptoms line up with Bender’s experience in UW Medicine’s long COVID clinic. “Especially the post-exertional malaise, brain fog, and fatigue — these are very common symptoms among the patients I see,” Bender says.

Study Assigned Varying Point Values to Different Symptoms

For this symptoms study, researchers examined data from 9,764 adults, including 8,646 who had COVID-19 and a control arm of 1,118 who did not have COVID-19. More than 30 symptoms across multiple body areas and organs were assessed in order to identify those most linked to people who had a previous COVID-19 infection.

Investigators established a scoring system, with a point value assigned to each symptom based on how unique it is to people with long COVID. Loss of taste and smell, which is an unusual symptom outside the context of the virus, was given a value of 8 points. Brain fog was given a value of 3, and gastrointestinal issues and fatigue were worth 1 point each.

Each participant was given a score based on their combination of the 12 identified symptoms. If a person scored 12 or higher, they met the study’s definition of long COVID.

“While the score developed in this study is an important research tool and early step toward diagnosing and monitoring patients with long COVID, we recognize its limitations,” said lead epidemiology investigator David C. Goff, MD, PhD, director of the division of cardiovascular sciences at the National Heart, Lung, and Blood Institute, part of the NIH, in a press release.

“All patients suffering from long COVID deserve the attention and respect of the medical field, as well as care and treatment driven by their experiences. As treatments are developed, it will be important to consider the complete symptom profile,” said Dr. Goff.

1 in 10 People Who Got COVID-19 from Omicron Developed Long COVID

The study also found that people who were unvaccinated, had multiple infections, or who had their first infection before the omicron variant arrived in late 2021 were more likely to have long COVID symptoms and more severe cases of long COVID.

Based on a subset of 2,231 patients in this analysis, 10 percent of the participants first infected on or after December 1, 2021, and enrolled within 30 days of infection had long COVID, according to the scoring system.

In other words, 1 in 10 people who contracted COVID-19 since the omicron wave began ended up with long COVID.

Researchers Identified Four Different Types of Long COVID

Scientists also found that certain symptoms occurred together and defined four subgroups or “clusters,” with a range of impacts on health.

“I think it’s interesting to see that they are attempting to figure out if there are different types of long COVID. From our experience in clinic, we know that there is a huge range of symptoms and there’s a huge range of how severely people are impacted by their symptoms,” says Bender.

Experts believe that’s probably due to different mechanisms of long COVID, says Bender. “We suspect that there are different types of long COVID. This matters because if there are different mechanisms or pathways that lead to long COVID, there would be different targets for treatments that we need to understand,” she says.

Many People Without Long COVID May Have Symptoms Such as Headache or Fatigue

“This study is one of the largest prospective cohort studies with an uninfected comparator group. Having a comparator group is essential in creating a definition for long COVID because many symptoms, such as fatigue and anxiety, are prevalent in both infected and uninfected individuals,” says Foulkes.

Researchers were able to identify symptoms — such as post-exertional malaise and loss of or change in smell or taste — that most distinguished people with a history of infection from those without, she adds.

Bender agrees that this robust control group sets this study apart. “Many of the initial studies looking at long COVID have been very important in trying to describe the disease, but we needed a study that included people without COVID-19 to look at their symptoms and compare the groups,” she says.

This study, along with others before it, have found that even people who didn’t have COVID-19 can sometimes have symptoms similar to those of people with long COVID, says Bender.

“If you imagine on any given day of the week, you might have a headache one day or you might be feeling tired one month. And if you took a survey about your health at that time, maybe you would have some of these symptoms that we see in long COVID, when it could be due to something totally unrelated or some other undiagnosed condition,” she says.

The Ultimate Goal: Treatments or Even a Cure for Long COVID

The results of dozens of other investigations from the RECOVER trial are being prepared for publication, according to the study website. “These findings are only the beginning. We will continue to get updated findings in the coming months and years,” says Bender.

The ultimate goal is evidence-based treatments or a cure for long COVID, says Bender.

While the long COVID score is an important research tool for identifying people with the condition, on its own, the score cannot reveal if someone does not have long COVID, says Foulkes.

“Further research in RECOVER will evaluate other data modalities, including laboratory tests and clinical and subclinical findings, to identify more people with long COVID who do not meet the symptom-based definition,” she says.

Long-term follow-up of people with long COVID is needed to better understand what factors are involved in recovery, says Foulkes.

In this study, investigators found that about a third of participants who met the study threshold for long COVID at six months did not meet the threshold at nine months, she says. “However, we do not know if these individuals have fully recovered. What we do know is that symptoms appear to come and go over time. By continuing to follow RECOVER participants, we hope to better understand the factors contributing to recovery,” says Foulkes.