COVID-19

5. How is SARS-CoV-2 transmitted and how can transmission be minimised?

SARS-CoV-2, like many viruses, spreads via aerosol or respiratory water droplets, especially via coughing/sneezing droplets onto mucous membranes in the eyes, nose and mouth. Therefore, the greatest risk of transmission is through close contact with patients (< 2m). Personal protective equipment is essential: face masks can reduce transmission by up to 80%, however due to viral particle survival on surfaces, reuse of PPE such as respirators (despite shortage of supply) is not recommended.

Reuse of respirators is not recommended, but if absolutely necessary there are some guidelines in the literature:

A two-step disinfection process can be used, based on an initial storage of PPE for ≥4 days, followed by ultraviolet light (UVC), dry heat treatment, or chemical disinfection.

The applied UVC dose should be at least 2,000 mJ/cm2 on both sides of masks, as well as heat treatment at 60°C for 90 minutes.

Note that treatments involving certain liquids and vapors may require caution, as steam, alcohol, and bleach all led to degradation in filtration efficiency, leaving the user vulnerable to viral aerosols: Vaporized hydrogen peroxide treatment was tolerated to at least 5 cycles by N95 masks. Standard autoclave treatment has been associated with no loss of structural or functional integrity to a minimum of 10 cycles for the 3 pleated mask models.

References:

https://doi.org/10.1101/2020.04.01.20050443

https://doi.org/10.1101/2020.04.02.20051409

https://doi.org/10.1101/2020.04.05.20049346


The virus can also be transmitted via contact with respiratory secretions; survival of SARS-CoV-2 for multiple days on touch surfaces (up to 72 hours on plastics). Decontamination of any surface that may have come into contact with respiratory droplets: door handles, touch surfaces, and imaging equipment (CT and MRI gantries, ultrasound probes) is essential. Washing hands with soap regularly, or using an alcohol-based hand gel, and avoiding touching the eyes, nose and mouth wherever possible, is the single most important method of reducing transmission.

Particularly for radiographers, - clean techniques for imaging are recommended to reduce transmission, including dual working where possible. Mobile imaging, avoiding transfer of the patient wherever possible, or “clean” transfer of patients to imaging departments when mobile imaging is not appropriate, is recommended.