Can you trust your sanitiser?

Burt Rodrigues, CEO of Biodx, provides insight into sanitisers and their residual efficacy.

Burt Rodrigues, CEO Biodx. Image credit: Biodx

The transmission of Covid-19 is a long way from over. Considering current infection rates are roughly 100 times more than our early days of level 5 lockdown.

In their article, Coronavirus on wood surfaces – is there a risk?, authors Konrad Domig and Rupert Wimmer say that it is still unclear to what extent the movement of goods poses a problem. In general, however, the environmental stability of coronaviruses is very low. In this context, the WHO has already gathered and published some data. Novel coronavirus applied to wood and cotton surfaces with buffer liquid can be replicated for twelve hours. On other surfaces (plastic, stainless steel, glass, masonry), they can demonstrably be reproduced for up to 96 hours.

With some caution, it can be deduced from these initial data that the duration of normal trading routes leads to the inactivation of the novel coronavirus (SARS-CoV-2). However, it should be noted that ‘fresh contamination’ could cause smear infections. Disinfection can effectively inactivate coronaviruses. In summary, says the article, it can be said that wood surfaces are relatively ‘virus-proof’. This is mainly due to the microstructure of wood and the presence of antimicrobial substances in the wood. In order to eliminate a residual risk, a one-week waiting period (‘quarantine’) for wood products or a surface disinfection (for example with 70% alcohol) for wooden products can be recommended. In addition, compliance with the general principles of hygiene (especially hand hygiene) is strongly recommended.

Over the past six months of living with the virus we’ve heard numerous stories of institutions such as schools, hospitals, shops and factories having to close down due to infection. This is often caused by the use of sub-standard disinfecting and sanitising products. But even when the correct products and protocols are in place, can we rely on the people dispensing and using them to do the job properly?

The first issue here is to make sure the products bought do what they advertise. Numerous places have now sold out of ‘authentic disinfecting’ products registered through the NRCS (national Regulator for Compulsory Specifications) or the SABS. Many of the products being sold right now simply don’t come with this type of guarantee. What buyers and managers of companies and government departments must do is if they don’t see these marks then at least the manufacturers must provide laboratory analysis demonstrating the product’s efficacy.

One of the biggest challenges is around the efficacy claims of chemical compounds. The message to the public has consistently been that the best way of keeping the virus at bay is soap and water which historically has always been the blueprint for good health. In other words, if a surface, whether on skin, a floor or countertop isn’t properly cleaned with detergent or soap and water before disinfecting, the efficacy of the disinfectant or sanitiser is diminished. The same applies to residual efficacy claims (the extended period of kill/destruction of a sanitiser or disinfectant on a surface after being applied), usually from several hours to several days.

What this means is that in the case of large areas in particular that need to be regularly disinfected, the responsibility to make sure these areas are now Covid-19 free comes down to the procedures carried out. If a surface is cleaned correctly, in other words, properly cleaned with soap and water or detergent leaving no organic matter behind, followed by an effective disinfectant at 06:00, this should allow for up to seven hours of protection.

“It all comes down to elbow grease – the effort that goes into the cleaning process. If for instance a hospital corridor is just swept, the disinfectant when applied will react with the organic material left on the floor and its efficacy immediately eroded, leaving people’s lives endangered. The same goes for other common touch surfaces such as counter tops, lift buttons, ATMs, light switches and door handles.

“If you follow the correct cleaning procedures then 90% of your problem is gone. You’ll often hear excuses such as lack of staff or proper cleaning equipment. What can also happen is that companies will try to save money by cutting back on the right amount of disinfectant to be used. This can lead to a very serious problem. If you lower the concentration and leave even 1% of virus on a surface you’ll create exponential resistance to your next application and in the future have to use a far higher concentration than originally specified to gain the appropriate kill/destroy rate, whilst in the meantime, leaving your staff/public in a highly vulnerable position.

The same rules apply around efficacy here as with surfaces. You go into a shopping mall, disinfect your hands and feel safe. BUT if your hands weren’t cleaned effectively with soap and water in the first place, meaning the sanitiser is put on top of dirty or moisturised hands, then your safety is far from secure.

Whether keeping your home, office, factory or yourself virus-free, the one constant is human behaviour. Be aware that any claims on the pack label of any disinfectant or sanitiser – be they efficacy (bacteria or virus kill/ destroy rate) or residual efficacy (duration of efficacy) – are subject to very specific conditions that usually require some sort of human effort before using. So, the tools are there. You’ve bought an approved/ registered product. If you use it strictly according to instructions, then 100% adherence equals 100% result.

Additional sources:

1. Konrad Domig, professor for food quality assurance
2. Rupert Wimmer, professor for natural material technology, Vienna University of Natural Resources and Life Sciences