Published: 12 May 2020
Interview: Importance of Residual Efficacy
In an interview with RBT’s Head of R&D for Viridis products, he shares his views on the research and development of Viridis and disinfectant technology.
Q: Please share why residual efficacy is important, especially in the development of disinfectant products such as Viridis.
A: Unlike other disinfectants like alcohol or bleach, Viridis forms a safe residual barrier upon drying. This means, that not only Viridis is very effective upon initial application in killing all the germs on a surface, it also continues to protect the surface afterwards. Viridis continues to work even if someone touches or contaminates the surface after the initial disinfection.
This is important for two reasons. First, it stops germs like bacteria or fungi from growing back. Second, it prevents the spread of germs from person to person through high-touch surfaces by disrupting this transmission channel.
One example where this is thought to happen is with the SARS-Cov-2 coronavirus, where infections can spread from person to person via surfaces.
Another example is the spread of the deadly multidrug resistant fungal pathogen Candida Auris, which adapted to survive outside the body on cold surfaces. This allows Candida Auris to spread from patient to patient via the environment. Disrupting this transmission through the environment will be a key to stop such pathogens from spreading.
Q: What are the advantages of a water-based disinfectant or hand sanitiser?
A: While alcohol based sanitisers evaporate immediately, usually within 30 to 60 seconds, Viridis actually stays on the hands and forms a residual barrier protecting for longer. Furthermore, alcohol can dry out the skin, while Viridis was tested to be compatible with sensitive skin.
The World Health Organisation (WHO) recommends alcohol-based hand sanitisers, because it has the most historical experience with these sanitisers. However, Viridis was tested to be more effective than 60% alcohol by an independent lab following a standard test protocol (EN 1500). Unfortunately, other alcohol-free, water-based products on the market are not more effective than alcohol, therefore they are not recommended by the WHO. In addition, most water-based products are either quat, phmb or chloride based and these are non-biodegradable actives that accumulate on surfaces and leave behind toxic residues.