Virucidal activity of Formulation I of the World Health Organization's alcohol-based handrubs: impact of changes in key ingredient levels and test parameters

Virucidal activity of chlorine dioxide in combination with acetic acid or citric acid and a surfactant, in presence of interfering substances, against polio-, adeno- and murine norovirus in suspension-, carrier- and four-field tests

Introduction

The aim of the study was to investigate whether the virucidal effectiveness of chlorine dioxid against adenovirus and murine norovirus can be improved by combining it with carboxylic acids and surfactants.

Method

The virucidal efficacy against polio-, adeno- and murine norovirus has been tested in presence of interfering substances in the quantitative suspension test according to EN 14476, the carrier test without mechanical action according to EN 16777, and in the four-field test according to EN 16615.Three chlorine-dioxide-based surface disinfectants were tested: a two-component cleaning disinfectant concentrate for large surfaces, a ready-to-use (RTU) foam, and an RTU gel.

Results

Cleaning and disinfecting preparations based on chlorine dioxide, applied at various concentrations, in combination with acetic acid or citric acid and surfactants, are virucidally active against polio-, adeno-, and norovirus after an exposure time of 5 minutes in presence of interfering substances.

Impact of concentration, temperature and pH on the virucidal activity of alcohols against human adenovirus

BACKGROUND

Adenoviruses belong to the stable nonenveloped viruses playing an important role in healthcare-associated infections mainly causing respiratory infections and epidemic keratoconjunctivitis. Hand disinfection with alcoholic preparations is therefore one of the most important measures to prevent such viral infections in hospitals and other medical settings.

METHODS

The inactivation of adenovirus type 5 by ethanol, 1- and 2-propanol, and 2 commercially available hand disinfectants was examined at different concentrations, temperatures, and pH-values.

RESULTS

For ethanol and 1-propanol the maximum virus-inactivating properties after 30 seconds exposure were found at a concentration of 60%-70% and 50%-60%, respectively, whereas with 2-propanol no activity was observed. The virucidal activity of all alcohols and the 2 hand disinfectants examined was increased when raising the temperature from 20°C to 25°C. By increasing the pH value to 9, a strong improvement of the activity of ethanol, 1-propanol and 1 hand disinfectant was observed, whereas pH lowering resulted in decrease of activity.

CONCLUSIONS

These results demonstrate the importance of physical parameters in the inactivation of adenoviruses by alcohols and will help to improve measures to reduce adenovirus transmission in healthcare settings.

Ethanol is indispensable for virucidal hand antisepsis: memorandum from the alcohol-based hand rub (ABHR) Task Force, WHO Collaborating Centre on Patient Safety, and the Commission for Hospital Hygiene and Infection Prevention (KRINKO), Robert Koch Institute, Berlin, Germany

BACKGROUND

The approval of ethanol by the Biocidal Products Regulation has been under evaluation since 2007. This follows concern over alcohol uptake from ethanol-based hand rubs (EBHR). If ethanol is classified as carcinogenic, mutagenic, or reprotoxic by the European Chemicals Agency (ECHA), then this would affect infection prevention and control practices.

AIM

A review was performed to prove that ethanol is toxicological uncritical and indispensable for hand antisepsis because of its unique activity against non-enveloped viruses and thus the resulting lack of alternatives. Therefore, the following main points are analyzed: The effectiveness of ethanol in hand hygiene, the evidence of ethanol at blood/tissue levels through hand hygiene in healthcare, and the evidence of toxicity of different blood/tissue ethanol levels and the non-comparability with alcoholic consumption and industrial exposure.

RESULTS

EBHR are essential for preventing infections caused by non-enveloped viruses, especially in healthcare, nursing homes, food industry and other areas. Propanols are effective against enveloped viruses as opposed to non-enveloped viruses but there are no other alternatives for virucidal hand antisepsis. Long-term ingestion of ethanol in the form of alcoholic beverages can cause tumours. However, lifetime exposure to ethanol from occupational exposure < 500 ppm does not significantly contribute to the cancer risk. Mutagenic effects were observed only at doses within the toxic range in animal studies. While reprotoxicity is linked with abuse of alcoholic beverages, there is no epidemiological evidence for this from EBHR use in healthcare facilities or from products containing ethanol in non-healthcare settings.

CONCLUSION

The body of evidence shows EBHRs have strong efficacy in killing non-enveloped viruses, whereas 1-propanol and 2-propanol do not kill non-enveloped viruses, that pose significant risk of infection. Ethanol absorbed through the skin during hand hygiene is similar to consumption of beverages with hidden ethanol content (< 0.5% v/v), such as apple juice or kefir. There is no risk of carcinogenicity, mutagenicity or reprotoxicity from repeated use of EBHR. Hence, the WHO Task Force strongly recommend retaining ethanol as an essential constituent in hand rubs for healthcare.

Hepatitis E virus is highly resistant to alcohol-based disinfectants

BACKGROUND & AIMS

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis worldwide and is mainly transmitted via the fecal-oral route or through consumption of contaminated food products. Due to the lack of efficient cell culture systems for the propagation of HEV, limited data regarding its sensitivity to chemical disinfectants are available. Consequently, preventive and evidence-based hygienic guidelines on HEV disinfection are lacking.

METHODS

We used a robust HEV genotype 3 cell culture model which enables quantification of viral infection of quasi-enveloped and naked HEV particles. For HEV genotype 1 infections, we used the primary isolate Sar55 in a fecal suspension. Standardized quantitative suspension tests using end point dilution and large-volume plating were performed for the determination of virucidal activity of alcohols (1-propanol, 2-propanol, ethanol), WHO disinfectant formulations and 5 different commercial hand disinfectants against HEV. Iodixanol gradients were conducted to elucidate the influence of ethanol on quasi-enveloped viral particles.

RESULTS

Naked and quasi-enveloped HEV was resistant to alcohols as well as alcohol-based formulations recommended by the WHO. Of the tested commercial hand disinfectants only 1 product displayed virucidal activity against HEV. This activity could be linked to phosphoric acid as an essential ingredient. Finally, we observed that ethanol and possibly non-active alcohol-based disinfectants disrupt the quasi-envelope structure of HEV particles, while leaving the highly transmissible and infectious naked virions intact.

CONCLUSIONS

Different alcohols and alcohol-based hand disinfectants were insufficient to eliminate HEV infectivity with the exception of 1 commercial ethanol-based product that included phosphoric acid. These findings have major implications for the development of measures to reduce viral transmission in clinical practice.

LAY SUMMARY

Hepatitis E virus (HEV) showed a high level of resistance to alcohols and alcohol-based hand disinfectants. The addition of phosphoric acid to alcohol was essential for virucidal activity against HEV. This information should be used to guide improved hygiene measures for the prevention of HEV transmission.

Inactivation of SARS-CoV-2 by 2 commercially available Benzalkonium chloride-based hand sanitizers in comparison with an 80% ethanol-based hand sanitizer

Background

The CDC and WHO recommend alcohol-based hand sanitizers to inactivate severe acute respiratory syndrome coronavirus-2 [SARS-CoV-2].

Aim

Benzalkonium chloride [BAK] is another hand sanitizer active ingredient that could be used in response to the global pandemic. Deployment of BAK-based hand sanitizers could reduce shortages of alcohol products and increase hand hygiene options where there are social, physical, and toxicological constraints on alcohol use.

Methods

Two commercially available BAK-based hand sanitizers, a concentrate diluted on-site with water and a ready-to-use product, were tested for activity against SARS-CoV-2 in the European Norm Virucidal Activity Suspension Test [EN14476]. A WHO and CDC-recommended 80% alcohol-based hand sanitizer formulation was tested in parallel.

Findings

Both BAK formulations demonstrated a ≥4.0 log₁₀ reduction of SARS-CoV-2 in 30 seconds, meeting the EN14476 performance standard for virucidal activity against SARS-CoV-2 and matching the in vitro effectiveness of the ethanol-based sanitizer.

Conclusion

These findings indicate that a commercial BAK hand hygiene formulation may be another effective means of inactivating the SARS-CoV-2 virus and could be considered as option for pandemic response.

Evaluating the Antimicrobial Properties of Commercial Hand Sanitizers

Hand sanitizers have been developed as a convenient means to decontaminate an individual’s hands of bacterial pathogens in situations in which soap and water are not available. Yet to our knowledge, no study has compared the antibacterial efficacy of a large collection of hand sanitizers. Using zone of growth inhibition and kill curve assays, we assessed the performance of 46 commercially available hand sanitizers that were obtained from national chain big-box stores, gasoline stations, pharmacies, and boutiques for antibacterial activity toward prototypical Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacterial pathogens. Results revealed substantial variability in the efficacy of many sanitizers evaluated. Formulations following World Health Organization-recommended ingredients (80% ethanol or 75% isopropyl alcohol) or those including benzalkonium chloride as the active principal ingredient displayed excellent antibacterial activity, whereas others exhibited modest or poor activity in the assays performed. Results also revealed that E. coli was generally more susceptible to most sanitizers in comparison to S. aureus and that there was significant strain-to-strain variability in hand sanitizer antimicrobial efficacy regardless of the organism evaluated. Further, tests of a subset of hand sanitizers toward severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) revealed no direct correlation between antibacterial and antiviral performance, with all ethyl alcohol formulations performing equally well and displaying improved activity in comparison to benzalkonium chloride-containing sanitizer. Taken together, these results indicate that there is likely to be substantial variability in the antimicrobial performance of commercially available hand sanitizers, particularly toward bacterial pathogens, and a need to evaluate the efficacy of sanitizers under development.

IMPORTANCE In response to the coronavirus disease 2019 (COVID-19) pandemic, hand hygiene has taken on a prominent role in efforts to mitigate SARS-CoV-2 transmission and infection, which has led to a radical increase in the number and types of hand sanitizers manufactured to meet public demand. To our knowledge, no studies have evaluated or compared the antimicrobial performance of hand sanitizers that are being produced under COVID-19 emergency authorization. Tests of 46 commercially available hand sanitizers purchased from national chain brick-and-mortar stores revealed considerable variability in their antibacterial performance toward two bacterial pathogens of immediate health care concern, S. aureus and E. coli. Expanded testing of a subset of hand sanitizers revealed no direct correlation between antibacterial performance of individual sanitizers and their activity toward SARS-CoV-2. These results indicate that as the pandemic subsides, there will be a need to validate the antimicrobial efficacy of sanitizers being produced.

Efficacies of the original and modified World Health Organization-recommended hand-rub formulations

The World Health Organization (WHO) hand-rub formulations have been in use around the world for at least the past 10 years. The advent of coronavirus disease 2019 (COVID-19) has further enhanced their use. We reviewed published efficacy data for the original and modified formulations. Only efficacy data according to the European Norms (EN) were found. The bactericidal efficacy of the original formulations was, under practical conditions, partly insufficient (EN 1500, only effective in 60 s; EN 12791, efficacy too low in 5 min). The first modification with higher alcohol concentrations improves their efficacy as hygienic hand rub (effective in 30 s). The second (0.725% glycerol) and third (0.5% glycerol) modification improves their efficacy for surgical hand preparation (effective in 5 and 3 min). The original and second modified formulations were tested and demonstrate activity against enveloped viruses including severe acute resiratory syndrome coronavirus 2 (SARS-CoV-2) in 30 s. The ethanol-based formulation is also active against some non-enveloped test viruses in 60 s (suspension tests, EN 14476). In-vivo data on the formulations would provide a more reliable result on the virucidal efficacy on contaminated hands but are currently not available. Nevertheless, the most recent modifications should be adopted for use in healthcare.

Virucidal activity of three ethanol-based hand rubs against murine norovirus in a hand hygiene clinical simulation study

Aim: We evaluated the efficacy of three ethanol-based hand rubs against murine norovirus in a proposed clinical simulation test (prEN 17430). Materials & methods: Virucidal activity was determined in 18 volunteers using three hand rubs: ethanol 72.4 and 89.5% v/v solutions, and 86% v/v gel. Subjects underwent testing with each product (3/6 ml for 15/30 s) and a reference solution (6 ml 70% v/v ethanol for 60 s). Results: Against murine norovirus, the reduction factors (RF; RF mean ± standard deviation log₁₀ reduction of postsampling) for ethanol gel 86% v/v (RF 1.96 ± 0.64), ethanol 89.5% v/v (RF 2.49 ± 0.59) and ethanol 72.4% v/v (RF 2.61 ± 0.50), were all significantly superior to that of the reference solution. Conclusion: All three hand rubs passed the criteria set out in prEN 17430 and exhibited excellent virucidal efficacy.

Efficacy of ethanol against viruses in hand disinfection

Ethanol is used worldwide in healthcare facilities for hand rubbing. It has been reported to have a stronger and broader virucidal activity compared with propanols. The aim of this review was to describe the spectrum of virucidal activity of ethanol in solution or as commercially available products. A systematic search was conducted. Studies were selected when they contained original data on reduction of viral infectivity from suspension tests (49 studies) and contaminated hands (17 studies). Ethanol at 80% was highly effective against all 21 tested, enveloped viruses within 30 s. Murine norovirus and adenovirus type 5 are usually inactivated by ethanol between 70% and 90% in 30 s whereas poliovirus type 1 was often found to be too resistant except for ethanol at 95% (all test viruses of EN 14476). Ethanol at 80% is unlikely to be sufficiently effective against poliovirus, calicivirus (FCV), polyomavirus, hepatitis A virus (HAV) and foot-and-mouth disease virus (FMDV). The spectrum of virucidal activity of ethanol at 95%, however, covers the majority of clinically relevant viruses. Additional acids can substantially improve the virucidal activity of ethanol at lower concentrations against, e.g. poliovirus, FCV, polyomavirus and FMDV although selected viruses such as HAV may still be too resistant. The selection of a suitable virucidal hand rub should be based on the viruses most prevalent in a unit and on the user acceptability of the product under frequent-use conditions.

Virucidal Activity of World Health Organization-Recommended Formulations Against Enveloped Viruses, Including Zika, Ebola, and Emerging Coronaviruses

The World Health Organization (WHO) published 2 alcohol-based formulations to be used in healthcare settings and for outbreak-associated infections, but inactivation efficacies of these products have not been determined against (re-)emerging viruses. In this study, we evaluated the virucidal activity of these WHO products in a comparative analysis. Zika virus (ZIKV), Ebola virus (EBOV), severe acute respiratory syndrome coronavirus (SARS-CoV), and Middle East respiratory syndrome coronavirus (MERS-CoV) as (re-)emerging viral pathogens and other enveloped viruses could be efficiently inactivated by both WHO formulations, implicating their use in healthcare systems and viral outbreak situations.