Researchers in Germany have demonstrated how an ozone-based decontamination device significantly reduces the volume of viral residue left on surfaces of two surrogate viruses for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
The article is available to read in full on the Journal of Hospital Infection website.
Ozone is a volatile and unstable molecule comprised of three oxygen atoms found in trace amounts naturally in the Earth’s atmosphere. Due to its reactive tendencies, it has been found to highly effective in killing viruses, bacteria, fungi, and other pathogens.
As the COVID-19 pandemic continues, caused by SARS-CoV-2, the need for appropriate sterilization of hospitals and medicinal equipment is increasing.
Due to many factors, several studies have highlighted that many hospitals generally fail to meet the environmental cleaning standards necessary to disinfect SARS-CoV-2 contaminated items. One study recently found that 49% of 23 hospitals averaged only 57% adequately clean surfaces, including inconsistent cleaning of patient telephones, call devices, and bedside rails.
Johannes Knobloch, a researcher from the Institute for Medical Microbiology at the University Medical Centre Hamburg-Eppendorf, Germany, lead a team to investigate the effects of ozone on a pair of SARS-CoV-2 surrogate viruses to determine whether ozone could be sufficient in decontaminating COVID-contact surfaces.
Knobloch and his team contaminated surfaces with two SARS-CoV-2 analogs: pseudomonas virus phi6 Φ6 (phi 6) and bovine coronavirus 30 L9 (BCoV). Φ6 is similar in size and shape to SARS-CoV-2, belonging to the Cystovidae family, having a lipid envelope suitable for use as a coronavirus surrogate. BCoV is a betacoronavirus, the same genus of SARS-CoV-2, and shares many similarities to the virus. Both pathogens have high levels of environmental persistence, so they were selected for the study.
Samples of both surrogate viruses were exposed to a number of common surfaces found in hospitals; ceramic tiles, stainless steel carriers, and furniture boards. These surfaces were kept in a 6 m3 air-tight room with a shelf. The samples were then exposed to an ozone-based device for automated room disinfection: the STERISAFETM Pro.
This device releases ozone into a room, which then should destroy any pathogens dwelling on surfaces and subsequently break up the ozone back into diatomic oxygen and purified air. The researcher team performed this as per the device instructions, also conducting plaque assays after each experiment to determine viral load. Ozone concentration and humidity were also measured throughout all the experiments.
The researchers found that ozone decontamination for both Φ6 and BCoV, although Φ6 required the addition of high humidity to achieve good sterilization. As BCoV is more genetically similar to SARS-CoV-2, it is likely that ozone would be similarly effective against the latter as it was the former.
The authors conclude that ozone room disinfection systems would provide an additional efficient and safe method for decontaminating hospital equipment. However, the researchers acknowledge their experiments were conducted in a small room, and due to the toxicity of ozone, doors, and vents in any room where ozone is used must be secure. This would add to the already expensive cost of running such a system, but while it has yet to be tested on the SARS-CoV-2 virus itself, the study provides a promising glimpse of cleaner hospitals and safer working and medical conditions.