In a comprehensive nationwide study published in the Open Forum Infectious Diseases, experts report that long COVID is not a singular condition, but rather a spectrum of persisting symptoms with varying presentations that fluctuate over time.
This revelation bears significant implications for the treatment of the millions of people worldwide grappling with the long-term impacts of COVID-19.
The researchers analyzed data gathered from nearly 6,000 participants – 4,504 of whom tested positive for the virus and 1,459 tested negative. A substantial portion of the study’s contributors, around 2,000 in total, hailed from King County and were engaged through the University of Washington School of Medicine.
The investigation brought to light four primary symptom categories that manifested among individuals who tested positive for COVID-19.
Approximately 72% of the cases reported minimal symptoms. Tiredness, headaches, and muscle or joint aches were experienced by 17% of the COVID-19 positive individuals.
A smaller subset of 5% had similar symptoms, additionally reporting a loss of taste and smell. The remaining 6% of cases presented symptoms across multiple bodily systems.
Study co-author Dr. Kari Stephens emphasized the clinical significance of these findings. “This study shows how the long-term symptoms from the virus change their presentation over time,” she said.
Potential for improved treatment
Dr. Stephens noted that most previous studies on long COVID primarily focused on individual symptoms, often neglecting to examine clusters or patterns of symptoms. Additionally, many lacked comparison groups and relied solely on data provided by healthcare professionals during clinic visits, rather than acquiring firsthand reports from patients.
“This study gives providers information about how long-term outcomes for COVID may look and present in patients over time,” said Dr. Stephens, highlighting the potential for these findings to shape individualized treatment plans for patients based on the manifestation of their symptoms.
A unique feature of this study was its direct patient engagement, allowing individuals to report symptoms independently of whether or not they had received medical care.
“While it is becoming increasingly clear that long COVID is not a singular condition, having data showing several distinct, symptom-defined phenotypes is a strong step towards developing evidence-driven approaches to treat the millions of people who continue to experience lingering symptoms,” said study lead author Michael Gottlieb, vice chair of research for Emergency Medicine at Rush University Medical Center.
New cases every day
According to Dr. Stephens, this research will be instrumental in informing funding and policy support for long COVID programs. She cautioned against overlooking the ongoing issue of long COVID as society begins returning to “normal,” reminding us that “new long COVID cases are occurring every day.”
As it stands, the Centers for Disease Control and Prevention (CDC) estimate that 11% of those who have contracted COVID-19 are now experiencing symptoms of long COVID.
This study involved participants self-reporting symptoms via detailed surveys from December 2020 to September 2022, for a period of up to 18 months.
This effort was part of the larger initiative called INSPIRE (Innovative Support for Patients with SARS-CoV-2 Infections), a federally funded collaboration among eight major academic medical centers, including UW Medicine, with the objective of deepening the understanding of COVID’s long-term effects.
The participants were recruited from eight major health organizations and contributed data through a standardized questionnaire. This marks the sixth study released by the INSPIRE group since the first documented U.S. COVID-19 case appeared near Seattle in January 2020.
More about long COVID
Long COVID, also known as post-acute sequelae of SARS-CoV-2 infection (PASC), refers to a range of symptoms that continue for weeks or even months after the acute phase of a COVID-19 infection has resolved. This phenomenon has been observed in a subset of individuals who have contracted the COVID-19 virus, caused by SARS-CoV-2.
Long COVID can affect nearly any organ system, with symptoms including fatigue, brain fog or cognitive impairment, shortness of breath, chest pain, joint or muscle pain, depression or anxiety, fever, loss of taste or smell, and more. These symptoms may fluctuate or relapse over time.
While the exact cause of long COVID was not yet known, it’s thought to be a combination of factors such as direct damage caused by the virus, a prolonged inflammatory response, an autoimmune response, or persistent presence of low-level virus. The probability of developing long COVID does not necessarily correlate with the severity of the initial infection; even individuals with mild or asymptomatic COVID-19 can experience these prolonged symptoms.
There is ongoing research into long COVID, including its causes, risk factors, and potential treatments. Care for patients with long COVID involves managing symptoms and supportive treatments. The condition emphasizes the importance of COVID-19 prevention measures, including vaccination, given that it can significantly impact quality of life and may lead to long-term health issues.
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