Person-to-person transmission through respiratory droplets is believed to be the primary way that the coronavirus is spread. However, experts do not want to discount the possibility that indirect transmission can happen when a person touches a surface contaminated with the virus, and then touches their own mouth, nose or even their eyes. This makes not only hand washing an essential practice, but also cleaning and disinfecting surfaces and items, especially those that are frequently touched.
Strict adherence to cleaning and sanitising/disinfecting guidelines is recommended to reduce the likelihood of spreading the disease in this way. Recently, disinfectant products and surface films that claim to have residual effects against the coronavirus have emerged. But how well do these products really work?
Efficacy of Residual Disinfectants in Real World Settings
Antimicrobial products, in liquid (spray) or film forms, are being marketed claiming to provide lasting surface protection. Whilst there is ongoing laboratory testing for such products, currently there is no real-world testing being done to determine their efficacy out in the field.
Some questions need to be raised when considering these residual products. It’s important to find out if the manufacturer provides detailed information about the product and the application process, including, but not limited to:
- Surface preparation process
- How do you ensure that the surface has been sufficiently cleaned of organic matter for the residual disinfectant film or spray to adhere to and coat the surface effectively and completely?
- Surface suitability
- Will the products adhere fully to all types of surfaces?
- If a surface is uneven, scratched, nicked, or cracked, will the coverage of the product be affected?
- Suitability of cleaning products, tools, and methods
- Will organic matter that builds up on the surface over time interfere with the efficacy of the product?
- How quickly will organic build-up render the product ineffective?
- If the surface needs regular cleaning to prevent organic matter build-up, won’t this wear away at the product and reduce its effectiveness?
- Won’t ingredients found in most cleaning products interfere with the residual disinfectant product’s efficacy?
- Product reapplication process
- If the product is in film form, does the first layer of product need to be removed prior to applying a new one? If so, what is the best way to remove the first film? How long does this take? How difficult will it be to remove the film if it has adhered to the surface firmly?
- If the first layer of film does not need to be removed prior to applying a new one, won’t this affect the new film’s ability to adhere to the surface and reduce its effectiveness?
- How often does the product need to be reapplied?
The TGA and Disinfectant Claims
The Therapeutic Goods Administration (TGA) sets out instructions for disinfectant testing that must be conducted to validate specific claims. Disinfectant products claiming virucidal, sporicidal, tuberculocidal, fungicidal or other bactericidal activity are categorised as “specific claims” under the TGA legislation and are required to be Listed in the Australian Register of Therapeutic Goods.
The TGA must give express permission for disinfectant products to claim an effect against SARS-CoV-2 and COVID-19 in advertising, including on the label. There are currently no TGA-approved testing protocols for residual activity, which means that no disinfectant product that claims residual effects can also claim to be TGA-approved. Companies doing so can potentially be in breach of the Therapeutic Goods Act.
Official Cleaning and Disinfecting Guidelines
These residual disinfectant products may seem to offer an easy and economical solution to the current situation; however, it is not the time to cut corners because you may be putting the health and lives of your workers, and the greater community, at risk. Until substantial evidence of real-world efficacy is available for these types of products, closely observing cleaning and disinfection guidelines recommended by Safe Work Australia and the Australian Department of Health is still best. Right now, it is of the utmost importance to ensure our workers’ health and safety and do all that we can to ensure that they are protected from COVID-19 as much as possible.