What researchers know now about long COVID

It’s been over four years since COVID-19 first emerged, and while restrictions have been lifted, millions of people around the world are still experiencing long COVID, the lasting symptoms following a COVID-19 infection. 

Long COVID has been deemed by some a “mass-disabling event,” as the condition often comes with debilitating symptoms that significantly disrupt people’s lives, including extreme fatigue, brain fog, heart palpitations, and insomnia. Researchers have been investigating the condition and are starting to find some answers about what causes it, who is most likely to be affected, and other questions. 

We’ve rounded up some of the most important recent findings on the condition. Read on to find out more. 

Getting reinfected with COVID-19 can also put you at risk of long COVID

A 2022 study found that COVID-19 reinfection can still put you at risk of long COVID. 

“The risk seems to be cumulative in the sense that, even if you dodged the bullet the first time and did not get long COVID, you can still get long COVID the second time or third time or the fourth time,” Dr. Ziyad Al-Aly, the director of the Clinical Epidemiology Center and chief of the Research and Education Service at the VA Saint Louis Health Care System, tells PGN. 

The study, which Al-Aly co-authored, used data from the Veterans Affairs national health care database. 

“People sort of already think that if they got COVID, and they got over it, and they emerge unscathed from it, it’s really fine,” Al-Aly adds. “It actually may still cause them to have problems a year or two down the road.” 

These findings highlight the importance of continuing to avoid getting infected and reinfected with COVID-19. 

Long COVID can affect almost every organ in the body

Al-Aly says another important finding about long COVID is that it can affect almost every organ in the body. 

“We’ve done studies on the brain; it affects the brain. We’ve done studies on the heart, and it clearly affects the heart,” Al-Aly says. “It affects the metabolic system: It increases [the] risk of diabetes, high cholesterol, kidney problems, gastrointestinal problems, and [it] also affects the immune system.” 

Who’s most at risk

While we’ve known for a few years that women and those who experienced more severe initial infections are more likely to have long COVID, researchers have also recently associated other risk factors with the condition.

A recent meta-analysis found that patients older than 40 had a significantly higher risk of long COVID compared to younger adult patients. 

Additionally, several studies have shown that people with comorbidities, like high blood pressure, obesity, chronic lung disease, depression, and diabetes, are at higher risk of developing long COVID.

The risk of long COVID for pregnant people

In a study published in January 2024, researchers found that around one in 10 pregnant people who get COVID-19 during pregnancy develop long COVID. The study, led by Dr. Torri Metz, associate professor of obstetrics and gynecology and maternal-fetal medicine subspecialist at University of Utah Health, was part of the National Institutes of Health-led RECOVER Initiative that aims to further understand long COVID. 

The study followed 1,503 people from across the country who got COVID-19 while pregnant and found that 9.3 percent of them developed long COVID six months or more after their initial COVID-19 infection. The most common symptoms for the participants were post-exertional malaise (when symptoms get worse after minor physical or mental activity), fatigue, and dizziness.

As for what this research means for pregnant people, “we know that mRNA vaccines are safe in pregnancy; there are a lot of data that support that,” Metz tells PGN.

“There is still circulating SARS-CoV-2 virus, and we know that people are still getting sick from it, so we do still encourage people to get vaccinated both to prevent the acute infection as well as potentially reduce the chances of long COVID,” she adds. 

Muscle abnormalities in long COVID patients after post-exertional malaise

A study conducted in Amsterdam and released in January 2024 found that the persistent fatigue some long COVID patients experience has a biological cause. 

The study’s participants were asked to cycle for 15 minutes. The activity caused post-exertional malaise in those with long COVID. One day after the test, the researchers looked at the blood and muscle tissue of those participants and found several abnormalities in their muscle tissue. 

“At the cellular level, we saw that the mitochondria of the muscle, also known as the energy factories of the cell, function less well and that they produce less energy,” Rob Wüst, assistant professor at Vrije Universiteit, said in a press release. 

“So, the cause of the fatigue is really biological. The brain needs energy to think. Muscles need energy to move. This discovery means we can now start to research an appropriate treatment for those with long-COVID,” said Dr. Michèle van Vugt, a professor of internal medicine and co-author of the study.

Inflammation and similarities with HIV infection and chronic fatigue syndrome

Scientists have also discovered more about the effects of COVID-19 on cognition and the blood-brain barrier, which allows substances like water and oxygen to pass into the brain. A study found that long COVID patients with brain fog show disruption of the BBB. 

Dr. Alba Azola, assistant professor of physical medicine and rehabilitation at Johns Hopkins Medicine who treats long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients, tells PGN that similar symptoms occur in those with an HIV infection, ME/CFS, and post-treatment Lyme disease syndrome. 

“So there’s this common pathway of the disruption of the blood-brain barrier causing brain inflammation,” Azola says. “And that [correlates] with worsening neurocognitive and neuropsychiatric impairments.”

What’s next?

Right now, the best way to prevent long COVID is to stay up to date on COVID-19 vaccines. This will reduce your chance of getting infected in the first place and potentially reduce the risk of getting long COVID.Meanwhile, long COVID patients are eagerly waiting for treatment options.

“Most of the research has really been surrounding epidemiology and risk factors,” says Metz. “And I think people who have long COVID in the community really want to see us move into intervention and try to see if there’s ways we can treat [long COVID patients] and have improvement in their symptoms.” 

Azola adds that the RECOVER Initiative is conducting four treatment trials, including for the use of Paxlovid, a medication used to treat COVID-19 infection. 

“[Medications like] antivirals, antihistamines, anticoagulants, all of those could be promising; things that modulate the immune system, microbiome, modulators, all of these things could potentially be beneficial or could actually improve long COVID,” notes Al-Aly. “But I think what we really need is trials at this scale that match the urgency and the gravity of the problem, and that’s really what is missing.”

For more information, talk to your health care provider.