A pair of new studies published about long COVID have shed more light on the sometimes-disabling condition that affects millions of people in the United States.
Scientists worldwide have been working to understand the wide-ranging condition, from risk factors to causes to potential treatments.
In the first study, 31 adults underwent lumbar puncture and blood draws to look for changes in their immune systems and also to look for changes in the nerve cells that could affect transmission of signals to the brain.
Among the participants, 25 people had neurocognitive symptoms of long COVID, such as memory loss or attention problems. Six participants had fully recovered from COVID, and 17 people had never had COVID.
Those who had COVID were diagnosed between March 2020 and May 2021. Their fluid samples were drawn at least three months after their first symptoms.
The results were published in the Journal of Infectious Diseases.
According to a summary of the study from the University of Gothenburg (Sweden), where the researchers work, “there were no significant differences between the groups when analyzing blood and cerebrospinal fluid for immune activation or brain injury markers. The findings thus suggest that post-COVID condition is not the result of ongoing infection, immune activation, or brain damage.”
In the second study, Norwegian researchers compared the likelihood of having 17 different long COVID symptoms based on whether a person had been infected with COVID. The analysis included 53,846 people who were diagnosed with COVID between February 2020 and February 2021, as well as more than 485,000 people who were not infected. Most people had not been vaccinated against COVID-19 during the time of the study.
The results were published in the journal BMC Infectious Diseases. Study results showed that people who had COVID were more than twice as likely to experience shortness of breath or fatigue. They were also more likely to experience memory loss or headache compared to people who never had COVID. Researchers only looked at symptoms that occurred at least three months after a COVID diagnosis.
They also found that hospitalization increased the risk for experiencing long COVID symptoms of shortness of breath, fatigue, and memory loss.
The authors noted that a limitation of their study was that, often, not all symptoms reported during a visit with a general practice medical provider are recorded in Norway, which could have affected the results.
A version of this article appeared on Medscape.com.