Are antimicrobial additives the answer to stopping the spread of COVID-19?

Periods of great uncertainty and challenge come with moments of opportunity and discovery. Architects, homeowners and building managers are looking for novel ways to address the impacts of COVID-19, which have influenced nearly every aspect of our daily lives. Antimicrobials certainly offer a potentially exciting and usable way to combat the virus, but the question of whether these additives may address the virus’ threat to human health still lingers. Would a stronger cleaning protocol be a better practice?

The definition of antimicrobials varies depending on use, function, production, regulation, benefits and more.¹ The more common definition defines antimicrobials as substances (natural, semisynthetic or synthetic) used to destroy or inhibit the growth of microorganisms.² Common types of microorganisms or microbes are bacteria, protozoans, and fungi such as mold and mildew. In the U.S., antimicrobials are classified as pesticides, since they are designed to kill organisms.³ Active substances considered antimicrobials range from silver and copper to much more complex chemicals.

Can antimicrobial additives stop the spread of viruses? This is not a new question, but it has returned to the forefront as we watch COVID-19, and its effects sweep across the world. Claims for antimicrobial effectiveness are determined by their performance against ‘test organisms’ that are relevant for public health or that are assumed to be harder to kill, but usually less pathogenic, than those that they are intended to kill in real-life situations.⁴ For a novel pathogen such as SARS-CoV-2 (the virus causing COVID-19), governments and researchers are doing additional studies now on what effectively sterilizes and kills the virus, but they’ve yet to make extensive claims for antimicrobials. For instance, Microban®—an industry leader of antimicrobial additives—does not claim antiviral properties for its technologies when built into products,⁵and they explicitly state that the additives are not intended to control disease pathogens.⁶

There is still a lack of understanding by the public for how long a prescribed bacteria or virus can survive upon contact with a treated surface, as well as which bacteria or virus may be killed by the specific coating. One common misconception is that microbes will be eradicated immediately once they touch a surface protected by an antimicrobial product. That’s simply not how these additives work. Even the fastest acting antimicrobial additives can take several minutes—if not hours—to make a thin layer of microbes inactive on a surface. And that’s just one end of a spectrum of results for antimicrobial products. Some additives may merely slow or stop the growth of germs without inactivating them, while others may kill a percentage of germs over time. Recent studies have shown that SARS-CoV-2 can only survive on copper and copper alloys for four hours,⁷ but we don’t know whether the microbes can still be spread in that time. This lack of clarity contrasts against the Environmental Protection Agency’s (EPA’s) stance on disinfectants. The EPA’s List N highlights what a disinfectant’s active ingredients are, the microbe(s) it will inactivate and the time it takes to make the pathogen inactive.

Overcoming misinformation to make healthier spaces
Consumer fears of deadly pathogens become easy targets for heightening the demand for antimicrobial agents. As long as misinformation and fear of a potentially harmful pathogen exists, there will always be a call for these products. Antimicrobial additives will likely have their place⁸, but there needs to be a better understanding of where they are appropriate and how they should be used. Without further evidence, antimicrobials can create a false sense of security and are not an adequate substitution for regular cleaning and disinfection. A copper alloy doorknob may be appropriate in a high-touch area, but copper should not become a default material everywhere—and it can’t be a substitute for proper cleaning and disinfection protocols.

As we continue to address the challenges of COVID-19 in our buildings, organizations and communities, we must remember that there is likely no single solution to mitigating disease transmission. Evidence currently suggests that rigorous cleaning protocols will work significantly better than any antimicrobial additives in response to COVID-19. Read about cleaning protocols and more in IWBI’s* Strategies from the WELL Building Standard to Support in the Fight Against COVID-19. *

References:
(1) Armacell. “What are Antimicrobials and how do they work?” April 2017. http://www.armacell.us/en/blog/post/what-are-antimicrobials-and-how-do-they-work/
(2) U.S. Environmental Protection Agency. “What are Antimicrobial Pesticides?” https://www.epa.gov/pesticide-registration/what-are-antimicrobial-pesticides
(3) U.S. Environmental Protection Agency. “Pesticides’ Impact on Indoor Air Quality.” https://www.epa.gov/indoor-air-quality-iaq/pesticides-impact-indoor-air-quality
(4) ASTM International. “ASTM E2755-15 Standard Test Method for Determining the Bacteria-Eliminating Effectiveness of Healthcare Personnel Hand Rub Formulations Using Hands of Adults.” https://www.astm.org/Standards/E2755.htm
(5) Microban. “A message from Microban International about Coronavirus (COVID-19)”, https://www.microban.com/message-about-covid-19
(6) Microban. “A message from Microban International about Coronavirus (COVID-19)”, https://www.microban.com/message-about-covid-19
(7) Van Doremalen, N., et al., “ Aerosol and surface stability of HCoV-19 (SARS-CoV-2) compared to SARS-CoV-1” N Engl J Med 2020; 382:1564-1567. https://www.nejm.org/doi/10.1056/NEJMc2004973
(8) U.S. Environmental Protection Agency. “Is there anything I can do to make surfaces resistant to SARS-CoV-2?” https://www.epa.gov/coronavirus/there-anything-i-can-do-make-surfaces-resistant-sars-cov-2