A new study was unable to find a cause for persistent long COVID symptoms, NPR reports.
Researchers from the US National Institute of Allergy and Infectious Diseases conducted a longitudinal study of long COVID among nearly 200 people who had laboratory-confirmed COVID-19 and 120 antibody-negative controls. As they report in the Annals of Internal Medicine, the NIAID team found that just more than half of those who had COVID-19 reported symptoms consistent with post-acute sequelae of SARS-CoV-2 infection (PASC), or long COVID.
All participants underwent a series of physical examinations, laboratory testing, and questionnaires, as well as assessments of cognitive and cardiopulmonary function. A portion underwent additional immunologic and virologic analyses. But, as they report in their paper, the researchers were unable to find anything to explain PASC from these tests.
But as NPR notes, that does not mean there is nothing wrong, just that these tests could not detect it. David Putrino from Mount Sinai Hospital tells it that the study did not go in-depth enough. NPR adds that the NIAID team is planning additional studies with fancier tests and that the National Institutes of Health is enrolling with thousands of patients in a new study.