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One of the lessons that we have learnt about the control of COVID-19, and well broadcasted to the public (WHO, 2020), is that “washing your hands with soap and water dissolves the virus”, which is based on established facts (e.g. Sickbert-Bennett et. al., 2005). Some detergents may, therefore, influence coronaviruses.
As part of its programme to provide guidance on hygiene procedures to control COVID-19, Holchem have commissioned studies to look at the effect of a range of Holchem detergents on coronaviruses. Six detergents were chosen to reflect the type of detergents commonly used in the food processing and food service industries, and included caustic, alkaline, neutral and acidic products. The detergents were tested against the human coronavirus strain 299E (HCoV-299E) using the method of the European virucidal disinfectant test EN 14476, under dirty conditions, according to their recommended concentrations and contact times. Note: EN 14476 was chosen as a test method not to make any disinfection claims, but as a simple way of assessing any virucidal activity of the detergents using an accepted test method.
The results are shown in Table 1.
The results show that all the detergents show virucidal effects, with a range of between 1.5 to 3.67 log orders of loss of infectivity (96.8 to 99.98% reduction) within their in-use concentrations. The surfactant-based products were the most effective, within their 5-minute contact times, rather than the extended contact times (20min) of the caustic and acidic products. In some way this endorses the WHO position that “washing hands with soap dissolves the virus”. The acidic product was more effective than the caustic detergents.
Any virucidal activity realised in practice from detergents, however, will be inconsistent and will depend on the level of soiling present on the surface. Whilst the studies were undertaken under ‘dirty’ test conditions (within the context of EN 14476), these are meant to be reflective of poorly cleaned, rather than uncleaned, surfaces. We can say, however, that detergency will have some role in reducing the presence (removal) and infectivity (of remaining) of coronavirus, particularly after much of the soiling present has been removed from the surfaces.
Disinfection is only ensured following detergent cleaning, when most of the soiling has been removed, and this work emphasises the need for disinfection to further reduce the infectivity of any viral particles present. And just for clarity, even though the detergent action may have virucidal properties, detergents should not be a replacement for disinfectants – combined cleaning and disinfection, two-stage programmes must continue where currently advocated.
Contact time (min)
Caustic detergent used in CIP, soak or boil-out operations
Chlorinated caustic detergent used in CIP, automated tray washing, soak or boil-out operations
Low alkalinity detergent used in foam applications or in manual cleaning
pH neutral surfactant-based detergent for manual cleaning
Surfactant-based detergent for manual cleaning
Phosphoric acid based detergent used in CIP, automated tray washing, soak or boil-out operations
Table 1 – loss of infectivity of HCoV-299e expressed as log reduction or percentage reduction, following exposure to a number of Holchem detergents.