Brooke Beery is Associate Editor of Optometry Times®.
Coating masks in antiviral materials such as copper and silver may complement existing methods of limiting viral transmission
Masks are a simple, but critical tactic in slowing the spread of the coronavirus.
N95 respirators appear to have a protective advantage over surgical masks in laboratory settings, but even cloth facial coverings over the nose and mouth reduce the spread of the virus SARS-CoV-2 by filtration.1
Despite their effectiveness at limiting microorganism circulation in the air, masks do not completely mitigate the risk of contagion because they are susceptible to microbial/viral colonization.2
One approach for further increasing mask protection from contaminated air filtering media lies in antiviral coatings. Researchers are exploring ways to coat masks in antiviral materials, including copper and silver, to complement existing methods of limiting viral transmission.3
Several studies have demonstrated the antibacterial and antifungal behavior of silver ions and nanoparticles, thanks to their broad-spectrum antimicrobial activity.4 When applied to facial coverings, it was demonstrated that a silver nanocluster/silica composite coating possessed virucidal effects.5
Two types of experiments were used to evaluate the antiviral activity of the coating, deposited on disposable, filtering face piece (FFP3) masks (3M), against the SARS-CoV-2.
In a first experiment 100 microliters (μl) of 50 TCID50/milliliter (ml) SARS-CoV-2 viral strain, isolated from a symptomatic patient, was added to each of 5 pieces (1 cm2), cut from the coated and uncoated facial mask, and incubated in a Petri dish at room temperature.5 Both the coated and uncoated samples were sterilized in vapor autoclave at 120 °C for 20 minutes in order to avoid any contamination from other microorganisms during the test.5
The second experiment was conducted similarly but kept the Petri dish open under a laminar flow of a safety cabinet and with samples not sterilized—in order to better simulate the real working condition of facial masks.5
For both experiments, higher infectivity was found in the uncoated facial mask and in the control, while the coated mask reduced the infectivity when the coating contained a lower silver concentration and completely removed the cytopathic effect when the coating contained a higher silver concentration.
ODs weigh in
Optometry Times® asked optometrists to weigh in on antiviral mask coatings. Editorial Advisory Board member David Geffen, OD, FAAO, says personal protective equipment is vitally important in ODs’ ability to safely see patients and insure the safety of staff and families.
“Masks with the added coating to help protect from a virus is a welcome addition to our options for protection,” Geffen says.“Costs are always a consideration, too.”
“Although in theory, an anti-viral mask makes sense—our first job is to do no harm while wearing masks,” Brujic says. “Sometimes there can be unforeseen health concerns with having things with anti-viral activity that close to the face. Additionally, without oversight on the technology, you are fully entrusting the manufacturer regarding its effectiveness.”
Dr. Coats says that although the data is still out on antiviral mask coatings, physical distancing, proper mask wearing, and eye protection help to reduce the spread of airborne viruses.
“Before spending 3 times more for a mask claiming to offer additional antiviral protection, I’d like to see more evidence-based data regarding the efficacy of adding copper and other antiviral coatings to masks compared to other types of face coverings used to protect against airborne viruses such as COVID19.”
1. Smith JD, MacDougall CC, Johnstone J, Copes RA, Schwartz B, Garber GE. Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis. CMAJ. 2016;188(8):567-574.
2. Möritz M, Peters H, Nipko B, Rüden H. Capability of air filters to retain airborne bacteria and molds in heating, ventilating and air-conditioning (HVAC) systems. Int J Hyg Environ Health. 2001 Jul;203(5-6):401-9.
3. Esposito S, Principi N, Leung CC, Migliori GB. Universal use of face masks for success against COVID-19: evidence and implications for prevention policies. Eur Respir J. 2020;55(6):2001260. Published 2020 Jun 18.
4. Deshmukh SP, Patil SM, Mullani SB, Delekar SD. Silver nanoparticles as an effective disinfectant: A review. Mater Sci Eng C Mater Biol Appl. 2019 Apr;97:954-965.
5. Balagna C, Perero S, Percivalle E, Nepita EV, Ferraris M. Virucidal effect against coronavirus SARS-CoV-2 of a silver nanocluster/silica composite sputtered coating. Open Ceramics. 2020;1:100006.