Can ozone inactivate SARS-CoV-2? A review of mechanisms and performance on viruses

Abstract

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic has challenged societies around the globe. Technologies based on ozone, a powerful oxidant, have been evaluated to inactivate this virus in aerosols and fomites. However, the high data diversity hinders the possibility of establishing a common ground for determining best practices for the use of these technologies. Furthermore, there is a lack of consensus regarding which are the main mechanisms of ozone virus inactivation. This critical review examined the most relevant information available regarding ozone application in gas-phase for different viruses inactivation (including recent publications dealing with SARS-CoV-2), and pointed towards envelope alteration as the main reaction pathway for enveloped viruses, such as is the case of SARS-CoV-2. It could also be concluded that gaseous ozone can be indeed an effective disinfectant, successfully inactivating viruses such us influenza A H1N1, MERS-CoV, SARS-CoV-1 or even SARS-CoV-2 in aerosols or fomites. In reviewed works, low ozone exposures, just around 0.1-0.4 mg L^-1 min, achieve about 4 log₁₀ of inactivation in aerosols, while exposures between 1 and 4 mg L^-1 min may be needed to guarantee an inactivation of 3-4 log₁₀ in different fomites. Although further studies are required, ozone is an effective candidate to be used against SARS-CoV-2 or other viruses in surfaces and indoor locations.

Keywords: Aerosols; COVID-19; Enveloped viruses; Fomites; Inactivation; Ozonation; SARS-CoV-2.

Graphical abstract

Fig. 1

Inactivation mechanisms of enveloped and non-enveloped viruses by ozone.

Fig. 2

CT value vs log₁₀ virus reduction for aerosols disinfection (empty dots) or vs log₁₀ Relative Infectious Ratio (RIR) (solid dots). RIR was calculated by dividing mean culture counts (PFU mL^-1) with mean qPCR values (genomes mL^-1) and normalized as proposed by Dubuis et al. (2020). Figure shows those experiments from Table S1 in Supplementary Material (extended version), with a relative humidity between 65%− 95% (26 points from 4 publications).

Fig. 3

CT value vs log₁₀ virus reduction for surfaces disinfection. It shows those experiments from Table S2 in Supplementary Material (extended version), with a relative humidity higher than 65% and virus deposited in solid matrixes and moderate ozone exposure (CT < 10 mg L^-1 min) (59 points from 10 publications).