Salt-Impregnated Surgical Masks Make Viruses Harmless Interview with:

Hyo-Jick Choi, PhD Assistant Professor, Department of Chemical and Materials Engineering University of Alberta Edmonton, AB, Canada T6G 1H9

Dr. Hyo-Jick Choi

Hyo-Jick Choi, PhD
Assistant Professor,
Department of Chemical and Materials Engineering
University of Alberta
Edmonton, AB, Canada T6G 1H9 What is the background for this study? What are the main findings?

Response: Respiratory diseases such as influenza transmitted either through breathing aerosols exhaled/coughed out by an infected person or through direct contact. Despite controversy over its efficacy, surgical mask has been widely used by general public during the past respiratory disease outbreaks because of low cost, easy wearability, and widespread use in normal day-to-day situation. Critical issue is that virus captured on the filter of the mask still maintains infectivity for long time, raising concerns of secondary infections and transmissions.

This led us to develop a strain-nonspecific and reusable airborne virus deactivation system based on salt recrystallization principle. Salt recrystallization is hypothesized to cause deactivation of viruses transmitted through aerosols via two successive processes:

1) salt on filter fiber dissolves upon exposure to the pathogenic aerosols and
2) salt crystallizes as aerosols evaporate.

To demonstrate the concept, we coated the fiber of the surgical mask filter with sodium chloride (NaCl) salt crystal and tested its performance using three different types of influenza viruses. Salt-treated filter provided higher filtration efficiency compared to non-treated regular filter and successfully destroyed multiple subtypes of influenza viruses trapped on the filter within few minutes, leading to significant infectivity loss. What should readers take away from your report?

Response: The principle of influenza virus deactivation using salt crystal does not depends on structural specificity of virus, nor specific interaction between viral antigen and filter surface. Since viruses would become inactive upon contact with the filter, masks can be reused multiple times without a safety concern. The unique advantage of our technology is that it can be applied to existing masks and air filters in hospitals, and can provide inexpensive, broad public and personal protection means against pandemic and epidemic pathogens. Importantly, ingredients used in our technology are benign and FDA approved, hence implementation for access to consumer market is expected to face minimum delays from relevant regulatory frameworks and laws. What recommendations do you have for future research as a result of this study?

Response: To demonstrate the concept, NaCl was selected in the preliminary work due to its widespread use. In the future, different inorganic and organic salt candidates will be studied to meet application-specific requirements, based on safety, stability in high humidity environments, and cost. Since salts collect moisture from the air at environmental conditions above their critical relative humidity (RH), salts with high critical RH will be preferred.

Another major effort will be focused on finding optimal salt conditions considering breathability, filtration efficiency, and deactivation capacity. In parallel, efforts will be dedicated to the development of a large-scale filter processing technology.

Lastly, studies will be extended to the development of other types of anti-viral applications utilizing this technology. Is there anything else you would like to add?

Response: I have been working on the following research areas:

1) Microfabricated vaccine delivery systems; and
2) Universal airborne pathogen deactivating system.

These research programs are inspired by an ideal two-pronged approach to deal with the menace of a viral disease. While the microfabricated drug delivery systems aim to develop cost-effective and self-administrable solid vaccines for viral diseases like influenza, the airborne pathogen deactivating systems strive to provide personal/public infection control measures against airborne transmissible pathogens in the event of an epidemic/pandemic outbreak. During an outbreak, solid vaccines will enable rapid immunization at large scale, protecting the general population, and pathogen deactivating systems will limit the spread of the virus, ensuring the safety of unimmunized population. Thank you for your contribution to the community.

Universal and reusable virus deactivation system for respiratory protection
Fu-Shi Quan, Ilaria Rubino, Su-Hwa Lee, Brendan Koch & Hyo-Jick Choi
Scientific Reports 7, Article number: 39956 (2017)

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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