Are long-term antimicrobial products useful against coronavirus?

Are long-term antimicrobial products useful against coronavirus?

No, they aren’t.  While there are many claims from material suppliers on the benefits of their antimicrobial additives, to the best of our knowledge at this time, no suppliers or manufacturers of the antimicrobial additives claim to be effective at killing viruses.

Recently, there has been a lot of interest in getting approvals for residual efficacy claims (i.e., claims that a product provides an ongoing antimicrobial effect beyond the initial time of application, ranging from days to weeks to months). There is significant desire from stakeholders and the public for products that are continuously active and can provide efficacy in between regular cleaning and disinfection. These products may reduce the level of re-contamination on high touch surfaces.

EPA has not evaluated the efficacy of any products claiming long-lasting efficacy against viruses; and, therefore, there are no EPA-registered products with label claims that they are effective against viruses over the course of hours to months (i.e., “residual” or “long lasting” efficacy claims)¹.

What are these antimicrobial products claiming to work on, then?

There are some antimicrobial pesticides that EPA calls “materials preservatives” that can be incorporated into articles. Known as “treated articles,” these plastics, textiles or other materials are treated with, or contain, a materials preservative to protect the article itself from mold or bacteria that can cause odor, discoloration or deterioration. 

For example, durable antimicrobial coatings only allow product claims of inhibiting odor-causing bacteria, mold, and mildew, excluding any claims regarding food-borne illnesses and disease-causing bacteria.

Therefore, these products are only approved to prevent odors, staining, or deterioration caused by select microbes on surfaces. They cannot claim to improve or protect public health.

So currently, the only EPA-registered products claiming long-lasting effectiveness are limited against control odor-causing bacteria on hard, non-porous surfaces, and there are no EPA-registered products that claim long-lasting disinfection.

Treated articles cannot claim that they are effective against viruses and bacteria that cause human illness. This means that they are not appropriate for controlling COVID-19.

According to Microban, the world leader in antimicrobial technologies and odor control solutions, their built-in antimicrobial technologies are effective against a plethora of product damaging microbes, but are not currently proven to have any antiviral properties when built-into products². Microban claims that the active technology itself may be effective against viruses in pure state, but not when incorporated into a product.  

Under FIFRA, all pesticide products (including antimicrobials) must be registered with the EPA prior to sale, distribution, or use. There are currently no antimicrobial products that are registered with the EPA so they cannot make claims of efficacy against the novel coronavirus.

Why are some products claiming a residual pathogen kill, then?

Products that have a residual kill claim fall under the EPA “treated article” exemption³.

These products cannot make human health claims. Most of these products are for odor control or construction materials. They are not ideal for healthcare or similar environments because they give a false sense of security and imply you don’t need to frequently clean surfaces.

Products treated with antimicrobial pesticides with claims such as those described in Section A below are likely to not be acceptable under the “treated articles exemption” because they imply or express protection that extends beyond the treated article or substance itself. Products treated with antimicrobial pesticides registered for such use and which only bear claims for protection of the article or substance itself such as those described in Section B below are likely to be acceptable and eligible for the “treated articles exemption”, assuming all other conditions have been met.

The EPA has indicated that the exemption doesn’t apply and EPA registration applies if company’s make claims such as^{4 :}

• Antibacterial
• Bactericidal
• Germicidal
• Kills pathogenic bacteria.
• Effective against E. coli and Staphylococcus.
• Reduces the risk of food-borne illness from bacteria.
• Provides a germ-resistant surface.
• Provides a bacteria-resistant surface.
• Surface kills common gram positive and negative bacteria.
• Surface controls both gram positive and negative bacteria.
• Surface minimizes the growth of both gram positive and negative bacteria.
• Reduces risk of cross-contamination from bacteria.
• Controls allergy causing microorganisms.
• Improves indoor air quality through the reduction of microorganisms.
• Unqualified claims of “Antimicrobial,” “Fungistatic,” “Mildew-resistant,” or “Preservative” used on it’s own is misleading and not exempt when it is part of the name of the product; or not properly qualified for non-public health use via references to the pesticidal properties and required qualifying statements located together printed in type of the same size, style, color, and with equal prominence.

In the example above of treated articles for microbial odor control, if the treated article is not an EPA registered product, the manufacturer needs to avoid inadvertently creating the impression that it provides protection against disease-causing bacteria, the EPA recommends qualifying statements such as: “This product does not protect users or others against disease-causing bacteria. Always clean this product thoroughly after each use.” or “This product does not protect users or others against bacteria, viruses, germs or other disease organisms. Always clean this product thoroughly after each use.”

What kind of testing or evaluation would they need to show efficacy to make a claim of effectiveness against SARS-CoV-2?

Products with residual effect claims that qualify for this expedited review fall into two major categories; (1) disinfectants that also provide residual efficacy, and (2) supplemental residual antimicrobial products (e.g., coatings, paints, solid surfaces) that do not meet EPA’s standards for disinfectants, but are intended to be used as a supplement to standard List N disinfectants.

Presently, EPA has an approved list for supplemental residual antimicrobial products⁵. All products on this list are supplemental which means they can complement, but do not replace, routine cleaning and disinfection using disinfectants on the EPA List N.^5,6

Can these alternative disinfectants be used on their own in place of the List N disinfectants?

Part of the challenge of proving efficacy for standalone use instead of a normal disinfectant are the testing endpoints you would need to use to demonstrate that the product works. 

With a normal disinfectant, the theory is if you had live virus on a surface, you could disinfect it immediately by applying the disinfectant. This inactivates the virus and you could evaluate this by measuring the log reduction in active virus that happens over time.

However, these treated articles usually work by having the presence of a chemical or substance that acts as an inhibitor to prevent the growth, or replication of a virus, which can only replicate within a living host cell. So, you would have to come up with a test showing if you had new live virus land on a surface treated with this chemical or substance, it would immediately render the virus inactive and stop its spread, just by it’s presence on the surface. This would depend upon the degree of exposure resulting from multiple factors upheld over a long period of time, such as concentration of the inhibitor, proximity, environmental exposure, temperature, humidity, presence of dirt, germs, organic or inorganic matter, durability of the coating or surface treatment, etc. 

It’s harder to prove that you can maintain the ideal conditions for these treated articles to work on their own over a long period of time without some degradation or less effective viral inactivation.

As a result, it’s much simpler to immediately disinfect against coronavirus using an approved disinfectant.

One of the serious issues with making treated articles widely available and unregulated in consumer products is that if they contain a pesticide that is antibacterial but the concentration is too low to be effective, it would not kill all bacteria leading some to survive and potentially become resistant strains, which leads to public health concerns as they complicate efforts to control and treat infections as they spread.

For more on how what is the best procedure to keep surfaces and devices clean check out our recommended protocol here.

1. Is there anything I can do to make surfaces resistant to SARS-CoV-2 (COVID-19)? https://www.epa.gov/coronavirus/there-anything-i-can-do-make-surfaces-resistant-sars-cov-2-covid-19 United States Environmental Protection Agency, (2020).
2. A message from Microban International about Coronavirus (COVID-19) https://www.microban.com/message-about-covid-19 , Microban (2020)
3. Consumer Products Treated with Pesticides https://www.epa.gov/safepestcontrol/consumer-products-treated-pesticides, United States Environmental Protection Agency (2020)
4. Pesticide Registration (PR) Notice 2000-1*, Notice to Manufacturers, Formulators, Producers and Registrants of Pesticide Products https://www.epa.gov/sites/production/files/2014-04/documents/pr2000-1.pdf , United States Environmental Protection Agency (2000)
5. List N Appendix: Supplemental Residual Antimicrobial Products for Coronavirus (COVID-19). https://www.epa.gov/pesticide-registration/list-n-appendix-supplemental-residual-antimicrobial-products-coronavirus United States Environmental Protection Agency (2020).
6. List N: Disinfectants for Coronavirus (COVID-19). https://www.epa.gov/pesticide-registration/list-n-disinfectants-coronavirus-covid-19 United States Environmental Protection Agency (2020).