Residual Virucidal Efficacy Testing

Residual disinfectant and virucidal efficacy claims must meet the EPA’s guidance for virucidal testing and criteria for making virucidal claims for residual products that provide virucidal efficacy beyond initial application. Element’s consultative experts can help you navigate the ever-changing and complex regulations for these antimicrobial products.

In response to increased interest in obtaining approval for residual efficacy claims stating that products continuously provide virucidal efficacy for days, weeks, or months, the US Environmental Protection Agency (EPA) recently released guidance for virucidal efficacy testing and criteria for making virucidal claims for residual products. Residual products are desired in areas where surfaces are touched multiple times between cleaning and disinfection cycles, such as public transportation. Residual products may be in the form of a coating on a surface or embedded into a surface. These products can provide additional disinfection or sanitization between the regular disinfection or cleaning cycles. Element’s residual virucidal efficacy testing services have been designed to meet the EPA regulations for virucidal efficacy claims.

Our industry-leading virologists have decades of experience testing products to established methods and custom protocols. As the most frequently used methodology is listed, connect with us today to explore alternative methods.

Residual efficacy claim testing services

Element offers residual efficacy claim testing to the following standard methodology. Our consultative scientists can also develop customized protocols to meet your specific needs.

Test Method for Determining the Residual Virucidal Activity of Dried Chemical Residues on Hard Nonporous Surfaces (with exposure and wear activity) – In this method, a series of glass or stainless steel surfaces are treated with the product and the product is allowed to dry over the surfaces. The treated surfaces then undergo a series of physical wear procedures followed by systematic low-level inoculation of test virus to simulate routine use and contamination of the surface. After completion of the wear cycles, the treated surfaces are inoculated with the test virus and held for the Sponsor requested exposure time to evaluate the residual efficacy of the surface. Following exposure, the carriers are neutralized and serial dilutions are performed. The dilutions are then assayed for viral infectivity by an assay method specific for the test virus. Appropriate virus, test substance cytotoxicity, and neutralization controls are run concurrently.

For the product to be considered an effective residual disinfectant, the EPA requires at least a 3 log (99.9%) reduction of the virus after 24 hours following application.

Physical Abrasion and Chemical Exposure Treatment Process for Hard, Non-porous Copper Containing Surface Products – A series of copper containing surfaces (or stainless steel carriers for the controls) are exposed to physical (mechanical) abrasions and chemical solutions, five times a day, five days a week for six weeks in this method. The abrasion and chemical exposure process is intended to represent a degree of normal and relevant physical wear, as well as reproduce potential effects resulting from repeated exposure of copper-containing surfaces to three different biocidal materials (chemical solutions).

The mechanical abrasions are performed using an abrasion tester. These carriers are then used in the efficacy test method (Test Method for Evaluation of Virucidal Activity of Hard, Nonporous Copper Containing Surface Products).

Test Method for Evaluation of Virucidal Activity of Hard, Nonporous Copper Containing Surface Products – This method calls for a series of copper containing surfaces (or stainless steel carriers for the controls), which have previously undergone physical wearing and chemical exposures, to be inoculated with the test virus and held for the Sponsor requested exposure time to evaluate the residual efficacy of the surface. Following exposure, the carriers are neutralized, and serial dilutions are performed. The dilutions are then assayed for viral infectivity by an assay method specific for the test virus. Appropriate virus, test substance cytotoxicity, and neutralization controls are run concurrently.

It is important to note the U.S. EPA requires at least a 3 log (99.9%) reduction of the virus in ≤2 hours.

Physical Abrasion and Chemical Exposure Treatment Process for Antimicrobial Surface Coatings (Long Lasting Surface Coating) –  A series of carriers containing the long-lasting surface coating (or stainless steel carriers for the controls) are exposed to physical (mechanical) abrasions and chemical solutions. Ten cycles of abrasions/chemical exposure are equal to 1 week of durability. The number of cycles can be increased in 1 week increments to support claims up to 4-weeks. The abrasion and chemical exposure process is intended to represent a degree of normal and relevant physical wear, as well as reproduce potential effects resulting from repeated exposure of antimicrobial coated surfaces to three different biocidal materials (chemical solutions). The mechanical abrasions are performed using an abrasion tester. These carriers are then used in the efficacy test method (Test Method for Evaluation of Virucidal Activity of Long Lasting Surface Products).

Test Method for Evaluation of Virucidal Activity of Long Lasting Surface Products –  In this method, a series of long lasting coating carriers (or stainless steel carriers for the controls), which have previously undergone physical wearing and chemical exposures, are inoculated with the test virus and held for the Sponsor requested exposure time to evaluate the residual efficacy of the surface. Following exposure, the carriers are neutralized and serial dilutions are performed. The dilutions are then assayed for viral infectivity by an assay method specific for the test virus. Appropriate virus, test substance cytotoxicity, and neutralization controls are run concurrently.

The U.S. EPA requires at least a 3 log (99.9%) reduction of the virus in not less than 1 hour but not more than 2 hours.

The Element advantage

The COVID-19 pandemic has led to an increased interest in and demand for products that offer residual antimicrobial protection beyond the initial application of the product. With decades of experience serving as a leader in antimicrobial testing, Element is the trusted partner for leading developers, manufacturers, and marketers of products with residual efficacy claims. With the ever-evolving COVID-19 pandemic influencing the market and regulations, our consultative scientific and regulatory experts stay up-to-date on market trends and regulatory guidance.

For more information about Element’s virucidal efficacy testing, to learn about additional methods and custom protocols, or to discuss your options for generating data to support residual claims for viral efficacy, contact us today.