Post-coronavirus Disease-2019 Fatigue

Background: COVID-19 is consistently spreading throughout the world, and the number of recovered patients is steadily increasing. Accordingly, a significant number of individuals will develop persisting post-COVID symptoms, while many of them will report on lasting fatigue. The main objective of the current study is to assess risk factors for the development of post-COVID-19 fatigue symptoms. As a secondary aim, the current study is intended to identify pathophysiology and explanatory mechanisms for the post-COVID-19 fatigue. Study design and population: a nested case-control study will be conducted at Rabin Medical Center (RMC), Beilinson Hospital. RMC runs a post-COVID-19 clinic for adult (age ≥18 years) recovered individuals (diagnosed using a polymerase chain reaction test from a nasopharyngeal sample), who are invited for a comprehensive medical evaluation. During a visit, all individuals undergo pulmonary function testing and an evaluation by an infectious diseases physician, a pulmonologist, and a social worker. The cohort of recovered COVID-19 individuals evaluated at RMC will serve as the population from which the current study participants will be consecutively sampled. The cases would be defined as such if report on lasting fatigue symptoms which appeared following COVID-19, while at least two months have elapsed since COVID-19 diagnosis and the lasting fatigue symptoms are present for at least six weeks. The controls would be defined as those that did not report on fatigue symptoms at any time point since one month following their diagnosis with COVID-19. Evaluation protocol of cases and controls: All participating individuals (cases and controls) will be assessed following the study protocol. The assessment will be conducted as follows: First assessment meeting (approximately one hour long) in which the participant will undergo physical examination and blood tests, fill the study questionnaires \[demographic, clinical and post-COVID fatigue questionn