Our hypothesis - that 21 days of mountain spa rehabilitation with ubiquinol supplementation could to accelerate regeneration of patients with post-COVID-19 syndrome, based on the improving platelet mitochondrial bioenergetic, decreasing of oxidative stress and improving of antioxidants protections of patients with post-COVID-19 syndrome.

The first new coronavirus originated from southeast China in 2003 (SARS - Severe Acute Respiratory Syndrome), and the second was originated from Middle East in 2012 (MERS - Middle East Respiratory Syndrome). In March 2020, the World Health Organization declared a global pandemic caused by the SARS-CoV-2 beta-coronavirus responsible for a new type of acute respiratory infection and atypical pneumonia. Persisting signs or symptoms over 12 weeks after the SARS-CoV-2 infection, are defined as post-COVID-19 syndrome. The main symptoms include shortness of breath, general fatigue, exhaustion, headaches, muscle and joint pain, cough, hair, taste and smell loss, sleep and memory disturbances, depression, sensitivity to sound and light.

SARS-CoV-2 viral infection occurs with higher incidence in patients with comorbidities such as diabetes mellitus Type 2, obesity, cardiovascular disease, chronic lung disease and cancer. In aged individuals immune system and mitochondrial dysfunction are a key factors in COVID-19 disease. Mechanical oxygen saturation is required primarily in patients with comorbidities and post-hospitalization pulmonary rehabilitation may be considered in all patients with COVID-19.

Many viruses modulate mitochondrial function, producing more reactive oxygen species, (ROS), cytokine storm, and stimulate inflammation. The investigators published the hypothesis that a target of the new SARS-CoV-2 virus could be mitochondrial bioenergetics and endogenous coenzyme Q10 level. Currently our question was partially answered by authors, who showed reduced mitochondrial bioenergetics in monocytes and peripheral blood mononuclear cells of patients with COVID-19, and the investigators found reduced platelet mitochondrial function in non-hospitalized patients after acute COVID-19 . In the last years isolated platelets from circulating blood are used for estimation of mitochondrial bioenergetics in various diseases, as in patients with chronic kidney diseases, in patients after kidney transplantation, in patients with rheumatoid arthritis. However, the effect of SARS-CoV-2 on platelet mitochondrial function in patients non-vaccinated, hospitalized after infection of SARS-CoV-2 (with post-COVID-19 syndrome), as well as effect of mountain spa rehabilitation on platelet mitochondrial function of patients with post-COVID-19 syndrome has not been published.

Mountain spa rehabilitation (MR) is beneficial for chronic pulmonary diseases, improving fatique, joint pain, psychological stress, sleep disorders and quality of life in patients with various diseases. The investigators assume that special spa rehabilitation in the mountain High Tatras may regenerate impaired mitochondrial metabolism of patients with post-COVID-19 syndrome, can improve physical and mental activity, immunity, reduce oxidative stress and contribute to the acceleration of recovery of patients with post-COVID-19 syndrome.

Inclusion Criteria:

• patients with post-COVID-19 syndrome, 3-6 months after hospitalization

Exclusion Criteria:

• no COVID-19 patients