Hygienic hand disinfection is the most important measure for the prevention of healthcare-associated infections, and therefore the proven reduction of microorganisms on hands is essential for clinical practice. To demonstrate efficacy, disinfectants should ideally be tested under conditions as close to real-life use as possible and against a range of relevant pathogens.
Disinfectants usually go through a two-step testing process. Step 1 tests are quantitative suspension tests in which the efficacy against various microorganisms is determined with an additional protein load. Step 2 tests are practical tests directly on the corresponding surface. For hand disinfectants, this is the skin (hands), therefore only test organisms that are not harmful to humans can be used.
For bactericidal efficacy, such a two-step process has existed for several years, including two central test standards:
Until recently, there was only a step 1 test for virucidal efficacy:
In May 2024, with EN 17430 a step 2 test for virucidal hygienic hand disinfection was published, which is designed to demonstrate the efficacy of a disinfectant under conditions similar to those in clinical practice.
The standard is performed with 18-22 volunteers. The volunteers wash their hands as preparation before being artificially contaminated with the surrogate murine norovirus suspension (Fig. 1, part 1). The dried fingers are then sampled to determine the pre-value, which indicates how many viruses are present on the hands before disinfection (Fig. 1, part 2). Hygienic hand disinfection is then performed (Fig. 1, part 3) – either with the reference alcohol (2 x 3 mL 70% ethanol (v/v), 2 x 30 seconds) or the test product (volume according to the manufacturer's instructions, exposure times between 30-60 seconds).
In both cases, the hands are disinfected using a standardized rub-in method. The hands are then sampled again to determine the post-value, i.e. the amount of infectious viruses remaining on the hands after disinfection (Fig. 1, part 4). The pre- and post-values can be used to calculate how effectively the test product and the reference alcohol have inactivated the viruses (Fig. 1, part 5). Finally, the effectiveness of the test product and the reference is compared. To pass EN 17430, the test product be at least as effective as a reference method. The reference thus determines the efficacy requirements for a disinfectant for hygienic hand disinfection.
With the publication of the new test standard, manufacturers now have 18 months to test products that are effective against viruses in accordance with EN 17430. For our Sterillium® products, we are working on incorporating the expert opinions according to EN 17430 into the national approvals.
The results of testing according to the different standards are the basis of a product claim for hygienic hand disinfection. Both the results from the suspension test (step 1, here: EN 13727 or EN 14476) and from the practical test (step 2, here: EN 1500 or EN 17430) must be taken into account.
However, the results of the two test stages may differ with regard to the exposure times. If this is the case, the longer exposure time must be used to ensure sufficient efficacy.
