# Antisepsis before skin injections: does the WHO recommendation for washing, instead alcohol-based antisepsis, achieve the same efficacy?

## TL;DR

This study compares the effectiveness of soap and alcohol for cleaning skin before injections and finds both methods equally effective.

## Contribution

The study provides empirical evidence that soap and alcohol-based antisepsis are equally effective for skin preparation before injections.

## Key findings

- Both soap and alcohol-based antisepsis reduced bacteria by around 1x lg.
- There was no significant difference in efficacy between the two methods.
- Alcohol-based antiseptics are preferred for user-friendliness when not using live vaccines.

## Abstract

Cleaning and reduction of microbial load on the skin is necessary before injections because of the colonization of the skin with resident flora and the presence of transient flora. Even after optimal skin antisepsis, there is a risk of infection, albeit a very low one.

The World Health Organisation (WHO) based on a systematic review on the infection risk after injections and skin antisepsis, does not recommend, alcohol-based skin antisepsis as being necessary before intradermal, subcutaneous and intramuscular injections and that washing the skin with soap and water alone is sufficient. As there is no clear evidence for the benefit of using alcohol over soap washing prior to injection, this study compared the efficacy of alcohol and soap on volunteers.

Liquid washing emulsion or potash soap (Sapo Kalinus, German Pharmacopoeia) or propan-2-ol 70%v/v, was applied to test areas on the upper arms of 23 volunteers. To test the soap, in trial 1 after 15-second swabbing, and a further 15 seconds of air-drying, the swabbed areas were rinsed, dabbed dry, and microbiological samples taken with sterile swabs. In trial 2, after 15 seconds of swabbing, samples were taken in the same manner. The comparator alcohol was rubbed in for 15 seconds in trial 1 and for 30 seconds in trial 2 without rinsing. Swabs were transferred into tryptic soy broth and suspensions plated onto agar.

The reduction of bacteria was around 1x lg and did not differ significantly between the soaps and propan-2-ol. There was also no difference when comparing the two trials.

One reason for the equivalent efficacy of both methods is probably the low colonization density of the skin of the arms.

Both methods are acceptable for legal reasons. However, if no live vaccines are applied, alcohol-based antiseptics are preferable because they are more user-friendly.