The emerging outbreak of the coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread worldwide. We prescribed some promising medication to our patients with mild to moderate pneumonia due to SARS-CoV-2, however such drugs as chloroquine, hydrossichloroquine, azithromycin, antivirals (lopinavir/ritonavir, darunavir/cobicistat) and immunomodulating agents (steroids, tocilizumab) were not confirmed as effective against SARS-CoV2. We, therefore, started to use auto-hemotherapy treated with an oxygen/ozone (O2/O3) gaseous mixture as adjuvant therapy. In Udine University Hospital (Italy) we performed a case–control study involving hospitalized adult patients with confirmed COVID-19 with mild to moderate pneumonia. Clinical presentations are based upon clinical phenotypes identified by the Italian Society of Emergency and Urgency Medicine (SIMEU—Società Italiana di Medicina di Emergenza-Urgenza) and patients that met criteria of phenotypes 2 to 4 were treated with best available therapy (BAT), with or without O3-autohemotherapy. 60 patients were enrolled in the study: 30 patients treated with BAT and O2/O3 mixture, as adjuvant therapy and 30 controls treated with BAT only. In the group treated with O3-autohemotherapy plus BAT, patients were younger but with more severe clinical phenotypes. A decrease of SIMEU clinical phenotypes was observed (2.70 ± 0.67 vs. 2.35 ± 0.88, p = 0.002) in all patients during hospitalization but this clinical improvement was statistically significant only in O3-treated patients (2.87 ± 0.78 vs. 2.27 ± 0.83, p < 0.001), differently to the control group (2.53 ± 0.51 vs. 2.43 ± 0.93, p = 0.522). No adverse events were observed associated with the application of O2/O3 gaseous mixture. O2/O3 therapy as adjuvant therapy could be useful in mild to moderate pneumonia due to SARS-CoV-2. Randomized prospective study is ongoing [Clinical Trials.gov ID: Z7C2CA5837].
