aerobic(4) Viral load(4) age(4) IMPROVE(4) Blood(4) COVID-19(4) increase(4) baseline(4) Health Organization(4) Trial(4) two groups(4) interleukin-6(4) control groups(4) immune(4) immune functions(4) Viral(4) Mild(4) Baseline measurements(4) immunoglobulin A(4) significantly(4) ranged(4) respiratory symptoms(4) Biomarkers(4) participated(4) World Health Organization(4) disease severity(4) All participants(4) progression(4) infected cases(4) Randomized(4)