Ozone Therapy for Prevention and Treatment of COVID-19

Background

During the early phases of the COVID-19 pandemic, clinicians and researchers searched widely for treatments that could ease the disease's hallmark features: excessive inflammation, low blood oxygen levels, and prolonged recovery in more severe cases. Medical ozone therapy, already used in some countries for chronic inflammatory and circulatory conditions, was proposed by several groups as a possible complementary option, on the basis of its reported anti-inflammatory, antioxidant and immune-modulating effects. This paper, published in April 2022, set out to summarise what the emerging clinical evidence on ozone therapy in COVID-19 actually showed at that point in the pandemic.

Study design

This is not a new clinical trial. It is a perspective article by a scientific advisor to the International Scientific Committee of Ozone Therapy (ISCO3), drawing together published research on ozone therapy and COVID-19 available up to early 2022. The author reviewed 25 intervention studies covering 508 patients treated with ozone alongside standard care, plus four prophylaxis studies covering 599 people who received ozone therapy in an attempt to prevent infection or reduce its severity. The protocols referenced across these studies typically involved systemic ozone administration methods such as major autohaemotherapy (where a patient's blood is treated with an ozone-oxygen mixture and reinfused) or rectal ozone insufflation, used alongside conventional COVID-19 care rather than in place of it.

Findings

Across the studies reviewed, the recurring findings associated with ozone therapy were: reduced markers of inflammation, including C-reactive protein; a shorter duration of assisted ventilation or respiratory support; improved blood oxygen saturation; in some studies, faster conversion to a negative PCR test; and, in some cohorts, a lower recorded mortality rate compared with patients who did not receive ozone. The author is explicit that these results come from preliminary clinical trials and expert opinion rather than large, definitive studies, and that the findings, while consistent in direction, varied in size and strength across the individual studies.

What the authors concluded

The author concluded that, despite the encouraging and broadly consistent direction of results across the early trials, there was not yet enough evidence to confirm ozone therapy as a proven treatment option for COVID-19. The paper explicitly calls for larger, more rigorous clinical studies before ozone therapy could be considered an established part of COVID-19 care.

Limitations of this study

As a perspective and narrative summary rather than a systematic review, this paper does not apply formal methods for searching the literature, appraising study quality, or statistically pooling results, so its conclusions should be read as an informed overview rather than a rigorously quantified synthesis. Many of the underlying studies were small, used different ozone protocols, doses and delivery routes, and were not all randomised or placebo-controlled, which makes it difficult to isolate the effect of ozone therapy itself from other aspects of patient care during the pandemic. The author is affiliated with the International Scientific Committee of Ozone Therapy, a body that advocates for ozone therapy research, which is relevant context for readers weighing the paper's conclusions. As the author himself states, larger and more rigorous clinical trials are needed before firm conclusions can be drawn.