Ultraviolet light therapy reduces viral load in critically ill COVID-19 patients

A team of scientists from the United States has recently evaluated the safety and efficacy profiles of ultraviolet-A (UVA) light applied via an endotracheal tube to critically ill coronavirus disease 2019 (COVID-19) patients. The findings reveal that specific and monitored application of UVA therapy is safe and highly effective in reducing endotracheal viral load and improving clinical outcomes of COVID-19 patients. The study is currently available on the medRxiv* preprint server.


Since the emergence of the COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), several studies have been done to identify potential therapeutic interventions for critically ill COVID-19 patients. However, a significant proportion of these interventions have failed to show promising outcomes in human clinical trials.

Treatment of various dermatological complications with ultraviolet-A (UVA) light therapy is a common practice in many clinical setups. Anti-microbial properties of UVA light have also been observed in several preclinical trials. In this context, studies have shown that exposure of coronavirus-229E transfected human tracheal cells with UVA light leads to activation of mitochondrial antiviral signaling protein (MAVS), which in turn reduces the expression of viral spike protein and restores the proliferation of infected cells.

In the current study, the scientists have investigated the safety level and therapeutic effects of the endotracheal application of UVA light on critically ill COVID-19 patients.

Study design

In the study, five hospitalized critically ill patients with polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection were enrolled. All the patients were recently intubated endotracheally for mechanical ventilation. A UVA therapy device equipped with a multi-LED UVA light catheter was connected to the endotracheal tube to deliver UVA light to the patients.

The endotracheal UVA therapy was administered for 20 minutes to all patients once daily for 5 consecutive days. Before the treatment, all patients received oxygen supplementation for 30 minutes.  

Important observations

At the time of initiation of mechanical ventilation (baseline), all patients were critically ill according to the World Health Organization (WHO) COVID-19 ordinal scale scores. Based on the sequential organ failure assessment (SOFA) scores, the mortality rate of the patients was 20 – 95%.

Analysis of clinical characteristics revealed that 4 out of 5 patients had elevated viral load at baseline. Only for one patient, the viral load could not be detected, possibly because of viral clearance. Upon completion of the UVA light therapy, a significant reduction in endotracheal viral load was observed in all patients. Regarding secondary infection, no significant alteration in the endotracheal bacterial load was observed during the UVA therapy. This indicates an added benefit of the therapy in preventing ventilation-related pneumonia.  

Importantly, a significant improvement in the WHO clinical severity score was observed on day 30 post-enrollment. Interestingly, a significant positive correlation was observed between the WHO clinical severity score and the reduction in viral load during the UVA therapy. Regarding biochemical parameters, a significantly reduced level of C-reactive protein was observed within 7 days of UVA therapy. Moreover, a non-significant reduction in interleukin-6 (IL-6) and ferritin levels was observed.  

No therapy-related adverse side-effects were observed in enrolled patients. No change in hemodynamic parameters and oxygen saturation levels was observed during the course of the therapy. All patients except one survived. Only one patient died on day 17 post-enrollment due to hemorrhagic complications of anticoagulation during the administration of extracorporeal membrane oxygenation.

Study significance

This is the first human study of its kind to evaluate the safety and efficacy profiles of UVA light internally applied to treat critically ill COVID-19 patients. The findings reveal that UVA therapy is safe for human use and is highly effective in reducing viral load and disease severity.

Previously, the current study scientists have identified antiviral effects of UVA therapy on positive-sense, single-stranded RNA viruses, such as coronavirus-229E. Based on the available literature, they believe that the reduced respiratory viral load observed in the study patients might be due to activation of MAVS protein signaling events by UVA light exposure.

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:
Dr. Sanchari Sinha Dutta

Written by

Dr. Sanchari Sinha Dutta

Dr. Sanchari Sinha Dutta is a science communicator who believes in spreading the power of science in every corner of the world. She has a Bachelor of Science (B.Sc.) degree and a Master's of Science (M.Sc.) in biology and human physiology. Following her Master's degree, Sanchari went on to study a Ph.D. in human physiology. She has authored more than 10 original research articles, all of which have been published in world renowned international journals.


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