text: Exercise Is Medicine for Immune Function Implication for COVID 19 This review supports that physical activity improves immunosurveillance and has the potential to counter COVID 19 infection and symptomatology at three prevention levels At the primary prevention level several lines of evidence support that physical activity is an immune system adjuvant in combating infectious diseases Recent epidemiological studies indicate that regular physical activity is associated with a reduced risk for COVID 19 similar to what has been reported for other respiratory infections Although specific COVID 19 related studies are needed data from investigations with other types of infectious agents such as influenza support the potential role of physical activity in augmenting COVID 19 vaccine efficacy secondary prevention level There is a growing awareness that COVID 19 can cause sustained morbidity in some patients and physical training and rehabilitation tertiary prevention level can be directed toward improvement in physical fitness quality of life and immune health 