IL6 and COVID-19: This analysis of our prospective RCT on using HBOT in severe COVID-19 confirmed the effectiveness of randomisation (except for IL-6), showed a clear trend towards fewer deaths in the HBOT group, confirmed the possibility of safely conducting HBOT in this patient group, showed a lower need for normobaric oxygenation in the group of patients treated with HBOT and demonstrated significant beneficial effects of HBOT on CRP, ferritin, LDH and CD3.