Natural history of long-COVID in a nationwide, population cohort study

Previous studies on the natural history of long-COVID have been few and selective. Without comparison groups, disease progression cannot be differentiated from symptoms originating from other causes. The Long-COVID in Scotland Study (Long-CISS) is a Scotland-wide, general population cohort of adults who had laboratory-confirmed SARS-CoV-2 infection matched to PCR-negative adults. Serial, self-completed, questionnaires collected information on pre-existing health conditions and current health six, 12 and 18 months after index test. Of those with previous symptomatic infection, 53% reported persistent incomplete/no recovery, 12% improved after six and 12 months, and one symptom was reported by 71.5% and 70.7% respectively of those never infected. At six and 12 months, one or more symptom was reported by 53.5% and 56.5% of those never infected. At 12 months, taste and smell function improved over time compared to the never infected group and adjusted for confounders. Conversely, late onset dry productive cough, and hearing problems were more likely following SARS-CoV-2 infection.

Claire E. Hastie, David J. Lowe, Andrew McAuley, Nicholas L. Mills, Andrew J. Winter, Corri Black, Janet T. Scott, Catherine A. O'Donnell, David N. Blane, Susan Browne, Tracy R. Ibbotson, Jill P. Pell