Four years ago in the spring of 2020, physicians and patients coined the term "long COVID" to describe a form of the viral infection from which recovery seemed impossible. (And the old nickname "long-haulers" seems so quaint now.)
What started as a pandemic that killed nearly 3 million people globally in 2020 alone would turn into a chronic disease causing a long list of symptoms — from extreme fatigue, to brain fog, tremors, nausea, headaches, rapid heartbeat, and more.
Today, 6.4% of Americans report symptoms of long COVID, and many have never recovered.
Still, we've come a long way, although there's much we don't understand about the condition. At the very least, physicians have a greater understanding that long COVID exists and can cause serious long-term symptoms.
While physicians may not have a blanket diagnostic tool that works for all patients with long COVID, they have refined existing tests for more accurate results, said Nisha Viswanathan, MD, director of the University of California Los Angeles Long COVID Program at UCLA Health.
Also, a range of new treatments, now undergoing clinical trials, have emerged that have proved effective in managing long COVID symptoms.
Catecholamine testing, for example, is now commonly used to diagnose long COVID, particularly in those who have dysautonomia, a condition caused by dysfunction of the autonomic nervous system and marked by dizziness, low blood pressure, nausea, and brain fog.
Very high levels of the neurotransmitter, for example, were shown to indicate long COVID in a January 2021 study published in the journal Clinical Medicine.
Certain biomarkers have also been shown indicative of the condition, including low serotonin levels. A study published this year in Cell found lower serotonin levels in patients with long COVID driven by low levels of circulating SARS-CoV-2, the virus that causes the condition.
Still, said Viswanathan, long COVID is a disease diagnosed by figuring out what a patient does not have — by ruling out other causes — rather than what they do. "It's still a moving target," she said, meaning that the disease is always changing based on the variant of acute COVID.
Promising Treatments Have Emerged
Dysautonomia, and especially the associated brain fog, fatigue, and dizziness, are now common conditions. As a result, physicians have gotten better at treating them. The vagus nerve is the main nerve of the parasympathetic nervous system that controls everything from digestion to mental health. A February 2022 pilot study suggested a link between vagus nerve dysfunction and some long COVID symptoms.
Vagus nerve stimulation is one form of treatment which involves using a device to stimulate the vagus nerve with electrical impulses. Viswanathan has been using the treatment in patients with fatigue, brain fog, anxiety, and depression — results, she contends, have been positive.
"This is something tangible that we can offer to patients," she said.
Curative treatments for long COVID remain elusive, but doctors have many more tools for symptom management than before, said Ziyad Al-Aly, MD, a global expert on long COVID and chief of research and development at the Veterans Affairs St. Louis Health Care System.
For example, physicians are using beta-blockers to treat postural tachycardia syndrome (POTS), a symptom of long COVID that happens when the heart rate increases rapidly after someone stands up or lies down. Beta-blockers, such as the off-label medication ivabradine, have been used clinically to control heart rate, according to a March 2022 study published in the journal HeartRhythm Case Reports.
"It's not a cure, but beta-blockers can help patients manage their symptoms," said Al-Aly.
Additionally, some patients respond well to low-dose naltrexone for the treatment of extreme fatigue associated with long COVID. A January 2024 article in the journal Clinical Therapeutics found that fatigue symptoms improved in patients taking the medication.
Al-Aly said doctors treating patients with long COVID are getting better at pinpointing the phenotype or manifestation of the condition and diagnosing a treatment accordingly. Treating long COVID fatigue is not the same as treating POTS or symptoms of headache and joint pain.
It's still all about the management of symptoms and doctors lack any US Food and Drug Administration–approved medications specifically for the condition.
Clinical Trials Exploring New Therapies
Still, a number of large clinical trials currently underway may change that, said David F. Putrino, PhD, who runs the long COVID clinic at Mount Sinai Health System in New York City.
Two clinical trials headed by Putrino's lab are looking into repurposing two HIV antivirals to see whether they affect the levels of circulating SARS-CoV-2 virus in the body that may cause long COVID. The hope is that the antivirals Truvada and maraviroc can reduce the "reactivation of latent virus" that, said Putrino, causes lingering long COVID symptoms.
Ongoing trials are looking into the promise of SARS-CoV-2 monoclonal antibodies, produced from cells made by cloning a unique white blood cell, as a treatment option. The trials are investigating whether these antibodies may similarly target viral reservoirs that are causing persistence of symptoms in some patients.
Other trials are underway through the National Institutes of Health (NIH) RECOVER initiative in which more than 17,000 patients are enrolled, the largest study of its kind, said Grace McComsey, MD.
McComsey, who leads the study at University Hospitals Health System in Cleveland, said that after following patients for up to 4 years researchers have gathered "a massive repository of information" they hope will help scientists crack the code of this very complex disease.
She and other RECOVER researchers have recently published studies on a variety of findings, reporting in February, for example, that COVID infections may trigger other autoimmune diseases such as rheumatoid arthritis and type 2 diabetes. Another recent finding showed that people with HIV are at a higher risk for complications due to acute COVID-19.
Lack of Urgency Holds Back Progress
Still, others like Al-Aly and Putrino felt that the initiative isn't moving fast enough. Al-Aly said that the NIH needs to "get its act together" and do more for long COVID. In the future, he said that we need to double down on our efforts to expand funding and increase urgency to better understand the mechanism of disease, risk factors, and treatments, as well as societal and economic implications.
"We did trials for COVID-19 vaccines at warp speed, but we're doing trials for long COVID at a snail's pace," he said.
Al-Aly is concerned about the chronic nature of the disease and how it affects patients down the line. His large-scale study published last month in the journal Science looked specifically at chronic fatigue syndrome triggered by the infection and its long-term impact on patients.
He's concerned about the practical implications for people who are weighted down with symptoms for multiple years.
"Being fatigued and ill for a few months is one thing, but being at home for 5 years is a totally different ballgame."