Introduction: Worldwide, large numbers of patients suffer from post COVID-19 condition, representing a substantial strain on the individual and the society. The aims of this study were to assess changes in sick leave, functional level, fatigue, dyspnea and exercise capacity 3-month after participating in a concentrated micro-choice based rehabilitation program for patients with post COVID-19 condition and explore predictors for change in fatigue.

Methods: In this prospective study 78 patients, aged 19-67 years with post COVID-19 condition were included in a three-day concentrated micro-choice based rehabilitation program. Fatigue and functional level were assessed at baseline,7-days and 3-month follow-up, while sick leave, dyspnea and exercise capacity were assessed at baseline and 3-month follow-up. Changes were explored using linear mixed effects models.

Results: There was a decrease in fatigue measured with Chalder Fatigue Questionnaire at 7-days (mean difference (MD) =-4.5, 95% CI: -5.5 to -3.4) and 3-month (MD=-5.5, 95% CI: -6.7 to -4.3) follow-up. Analyses revealed no statistically significant moderators for change in fatigue. Sick leave rate and dyspnea were reduced (p<0.001) and exercise capacity and functional level increased (p<0.001) at 3-month follow-up regardless of severity of fatigue at baseline and 97.4% completed the intervention.

Conclusion: Micro-choice based concentrated rehabilitation for post COVID-19 condition showed rapid improvements in fatigue and functional levels, sustained over time. The findings are of great importance addressing the tremendous challenges of disability due to post COVID-19 condition.