Selection of parameters for thermal coronavirus inactivation - a data-based recommendation

Area of Science:

• Microbiology
• Infectious Disease Control
• Materials Science

Background:

• Healthcare workers and the public use personal protective equipment (PPE), like face masks, to prevent SARS-CoV-2 transmission.
• Sterilization of reusable PPE is crucial, with thermal inactivation being a potential method.
• High-temperature autoclaves are not always accessible or suitable for gentle sterilization.

Purpose of the Study:

• To determine the temperature dependence of coronavirus inactivation rates.
• To establish the required time for thermal inactivation of coronaviruses at various temperatures.
• To assess the feasibility of low-temperature thermal inactivation for PPE sterilization.

Main Methods:

• Utilized data from published coronavirus thermal inactivation studies.
• Applied Arrhenius models to determine the temperature dependence of the rate constant k(T).
• Developed a worst-case Arrhenius model to account for variations in sample properties.

Main Results:

• Arrhenius models effectively described thermal inactivation properties for coronaviruses.
• SARS-CoV and SARS-CoV-2 inactivation could be modeled together.
• Sample properties like high protein content or dry conditions can influence inactivation difficulty.
• A worst-case model was developed to include all sample types, even challenging ones.

Conclusions:

• Coronaviruses can be inactivated at relatively low temperatures with adequate exposure times.
• For a 5 log-reduction, typical times at 60°C, 80°C, and 100°C are approximately 32.5, 3.7, and 0.5 minutes.
• Under difficult conditions, the worst-case model suggests longer times: 490 minutes at 60°C, 55 minutes at 80°C, and 8 minutes at 100°C.