International

EN 17430: Practical testing of virucidal efficacy for hygienic hand disinfection

Two women in a laboratory Two women in a laboratory

Test standards for (hand) disinfectants

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:

  • Step 1 (EN 13727): Quantitative suspension test for bactericidal efficacy of a disinfectant. Here, a disinfectant is added to a bacterial suspension and, after a defined period of time, it is determined whether the disinfectant has sufficiently reduced the number of living bacteria.

  • Step 2 (EN 1500): Practice-like test for bactericidal efficacy of a disinfectant. Hands of 18-22 volunteers are artificially contaminated with a test organism that is not harmful to humans and hands are disinfected afterwards. To pass the test, a hand disinfectant must be at least as effective as a reference method.

Until recently, there was only a step 1 test for virucidal efficacy:

  • Step 1 (EN 14476): Quantitative suspension test for virucidal efficacy of a disinfectant. Here, a disinfectant is added to a virus suspension and, after a defined period of time, it is determined whether the disinfectant has sufficiently reduced the number of infectious viruses.

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 EN 17430 test standard (step 2)

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).

Schematic representation of efficacy testing according to EN 17430
Fig 1 Schematic representation of efficacy testing according to EN 17430. The volume and application time of the test product are specified by the manufacturer, with the minimum duration being 30 seconds in accordance with the test standard.

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.

Two standards – which is the relevant one?

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.

Two-step process for bactericidal efficacy

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