High-Intensity Ultraviolet-C Irradiation Efficiently Inactivates SARS-CoV-2 Under Typical Cold Chain Temperature

Area of Science:

• Microbiology
• Infectious Diseases
• Public Health

Background:

• SARS-CoV-2 contamination of cold chain items poses a public health risk.
• Effective, low-temperature sterilization methods are needed for cold chain applications.
• The efficacy of ultraviolet (UV) sterilization against SARS-CoV-2 at low temperatures is not well understood.

Purpose of the Study:

• To investigate the sterilization effect of high-intensity ultraviolet-C (HIUVC) irradiation on SARS-CoV-2 and Staphylococcus aureus.
• To evaluate HIUVC efficacy on different carriers at 4°C and -20°C.
• To establish a correlation between HIUVC sterilization of SARS-CoV-2 and Staphylococcus aureus.

Main Methods:

• Exposure of SARS-CoV-2 and Staphylococcus aureus on carriers to HIUVC at 4°C and -20°C.
• Determination of log reduction for SARS-CoV-2 at a dose of 15.3 mJ/cm².
• Modeling of survival curves using Weibull, biphasic, log-linear tail, and log-linear models.

Main Results:

• A dose of 15.3 mJ/cm² achieved over a 3-log reduction of SARS-CoV-2 on gauze at both 4°C and -20°C.
• SARS-CoV-2 vulnerability to HIUVC was not significantly different between 4°C and -20°C.
• The biphasic model best fitted the survival curves (R² 0.9325–0.9878), and a correlation between HIUVC sterilization of SARS-CoV-2 and Staphylococcus aureus was established.

Conclusions:

• HIUVC is effective for sterilizing SARS-CoV-2 on cold chain items at low temperatures (4°C and -20°C).
• Staphylococcus aureus can be used as a marker organism to assess the efficacy of cold chain sterilization equipment employing HIUVC.
• This study provides data supporting the use of HIUVC in low-temperature environments and a method for evaluating sterilization equipment.