New Research Reveals That Long COVID Is Not a Single Condition

The study revealed that symptoms evolve over time, with numerous patients experiencing headaches and fatigue.

New data from a nationwide study recently published in the journal Open Forum of Infectious Diseases suggests that Long COVID is not a single condition, and should not be treated as such.

This research examined the lasting symptoms of COVID-19 patients at both three and six months after diagnosis. Out of the 5,963 individuals who took part in the study, 4,504 had tested positive for COVID-19, while 1,459 tested negative. Many of the participants, 2,000 in all, came from King County through the University of Washington School of Medicine.

The four major symptom categories for people who tested positive for COVID-19 included:

• Minimal symptoms (72% of the cases)
• Tiredness, headache, and muscle/joint aches (17% of cases)
• Tiredness, headache, and muscle/joint aches with loss of taste and smell (5% of cases)
• Symptoms across multiple systems (6% of cases)

This study is clinically significant because it shows how the long-term symptoms from the virus changes its presentation over time, noted Kari Stephens, senior author and the Helen D. Cohen Endowed Professor and research section head in  the Department of Family Medicine and an adjunct professor in the Department of Biomedical Informatics and Medical Education at the University of Washington School of Medicine.

Most long COVID studies have focused primarily on the individual symptoms without considering clusters or patterns of symptoms. Many did not have comparison groups and focused only on data captured by providers during clinic visits, rather than directly from patients, she said.

“This study also gives providers information about how long-term outcomes for COVID may look and present in patients over time,” she said. “This study will help us understand how we need to treat long COVID over time, in very specific ways for each patient depending on how their symptoms present.”

This study is unique in that people were able to report symptoms directly, regardless of whether or not they 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 Michael Gottlieb, vice chair of research for emergency medicine at Rush University Medical Center and lead author.

Overall, the study will help determine funding and policy support for long COVID programs, Stephens added.

“We don’t want to forget about long COVID as we all go back to “normal,”” Stephens said. “New long COVID cases are occurring every day.”

Currently, the CDC estimates that 11% of those who contracted COVID-19 are now experiencing symptoms of long COVID.

Reference: “Long COVID Clinical Phenotypes up to 6 Months After Infection Identified by Latent Class Analysis of Self-Reported Symptoms” by Michael Gottlieb, Erica S Spatz, Huihui Yu, Lauren E Wisk, Joann G Elmore, Nicole L Gentile, Mandy Hill, Ryan M Huebinger, Ahamed H Idris, Efrat R Kean, Katherine Koo, Shu-Xia Li, Samuel McDonald, Juan Carlos C Montoy, Graham Nichol, Kelli N O’Laughlin, Ian D Plumb, Kristin L Rising, Michelle Santangelo, Sharon Saydah, Ralph C Wang, Arjun Venkatesh, Kari A Stephens and Robert A Weinstein, 31 May 2023, Open Forum Infectious Diseases.
DOI: 10.1093/ofid/ofad277

The nearly 6,000 participants began self-reporting symptom data via detailed surveys beginning in December 2020 and were followed for up to 18 months. This part of the study concluded in September 2022.

INSPIRE, or Innovative Support for Patients with SARS-CoV-2 Infections, is a federally funded collaboration of eight major academic medical centers, including UW Medicine, seeking to better understand the long-term effects of COVID. The patients were recruited from eight major health organizations and self-reported their symptoms in a standardized questionnaire. The INSPIRE group has been studying COVID since the first documented U.S. case was found just outside the Seattle area in January 2020. This is the sixth study released by the group.