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Is the Post-Viral Syndrome Affecting Millions of Americans Actually Long COVID?
Approximately 40% of people with a post-viral syndrome resembling long COVID, but without a test result confirming SARS-CoV-2 infection, showed evidence of an immune response to SARS-CoV-2 infection, according to study findings published online in Neurology: Neuroimmunology & Neuroinflammation.
“Since most long COVID clinics are only accepting patients with a positive test result, these people experiencing identical symptoms are left without specialized care and excluded from research studies on long COVID,” said study author Igor J. Koralnik, MD, of Northwestern Medicine Comprehensive COVID-19 Center in Chicago, Illinois, and a fellow of the American Academy of Neurology. “Our data suggest that millions of Americans with post-viral syndrome may have been exposed to SARS-CoV-2 at the beginning of the pandemic, and they deserve the same access to care and inclusion in research studies as people with a confirmed COVID diagnosis.”
Early in the pandemic, millions of Americans were exposed to the virus but were unable to access COVID-19 testing due to widespread limitations, researchers pointed out. Many went on to develop a post-viral syndrome that includes neurologic symptoms, such as problems with memory and thinking skills, headache, and fatigue, similar to long COVID.
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For the study, researchers tested 29 people with post-viral syndrome for antibodies to two proteins that reflect an immune response to a previous COVID-19 infection: nucleocapsid protein and spike protein. Also tested and included in the study were 32 patients matched for age and sex with long COVID and a positive COVID-19 test result, as well as 18 people with no symptoms and no known SARS-CoV-2 exposure or test result.
Of participants with post-viral syndrome, 41% had immune responses consistent with prior exposure to COVID and that were similar to patients in the long COVID group. Three-quarters had responses against the nucleocapsid protein, and a half had responses against the spike protein.
Participants with post-viral syndrome also had similar symptoms and similar results on tests of processing speed, attention, and executive function as participants with long COVID.
The small number of patients with post-viral syndrome is a limitation of the study. Researchers also pointed out that more participants may have shown evidence of immune responses if their blood samples had been collected closer to the start of symptoms.
“Unlike our clinic, about 70% of post-COVID clinics in the United States do not accept people with long COVID symptoms who do not have a positive test result for COVID,” Dr Koralnik said. “Our data suggest that at least 4 million people with post-viral syndrome similar to long COVID may indeed have detectable immune responses to support a COVID diagnosis. More research is needed to confirm our findings.”
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