The alcohol-based hand disinfection formulations recommended by the WHO show effectiveness against the monkeypox virus

The alcohol-based hand disinfection formulations recommended by the WHO show effectiveness against the monkeypox virus

In a recently published study in Emerging infectious diseases Researchers demonstrated the effectiveness of two alcohol-based hand sanitizer solutions recommended by the World Health Organization (WHO) for inactivating monkeypox virus (MPXV).

Lernen: Effiziente Inaktivierung des Affenpockenvirus von der Weltgesundheitsorganisation empfohlene Formulierungen und Alkohole zum Einreiben der Hände. Bildnachweis: MIA Studio/Shutterstock

background

It is important to take hygienic hand measures to exclude health care and outbreak-causing deadly viral infections. Therefore, in 2009, WHO proposed and introduced two alcohol-based formulations, I and II, for surgical and hygienic hand disinfection in healthcare settings. However, researchers have not evaluated their inactivation effectiveness against MPVX.

A concerning fact about MPXV that makes it a public health concern is that it spreads among people who have not traveled to endemic areas. Its clinical and epidemiological patterns are novel in contrast to previous outbreaks. It is also remarkably more stable than other smallpox viruses. It is therefore necessary to confirm which disinfectants and biocides can effectively inactivate MPXV.

The study

In the present study, researchers obtained virus isolate MPXV-DUS_001 from a patient in Düsseldorf, Germany, who was infected early during the 2022 MPXV outbreak. They passaged this isolate twice on Vero 76 cells before experimental use.

First, the team cultured Vero 76 cells in Dulbecco Modified Eagle (DME) medium and inoculated them at a concentration of 0.33 × 106 cells/ml for MPXV preparation. Next, after changing the medium, they inoculated these cells with MPXV at a multiplicity of infection (MOI) of 0.01. The team incubated Vero 76 cells at 37°C until they observed a visible cytopathic effect (CPE). They proceeded to harvest MPXV-infected cells by scraping, then vortexing extensively, and then extracting the infectious supernatant from cell debris by centrifugation. Finally, the researchers aliquoted and titrated the virus suspensions according to standard protocols and stored them at −80 °C for future use. The researchers confirmed that MPXV-DUS_001 was MPXV clade II using panorthopoxvirus-specific quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR).

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The team followed European guideline EN14476 to evaluate the virucidal activity of WHO formulations I and II. Since these formulations are 80% ethanol and 75% isopropanol based, they also assessed MPXV susceptibility to ethanol and 2-propanol. The protocol called for mixing eight parts disinfectant with one part each of bovine serum albumin and MPXV to achieve a final concentration of 0.3 g/L. The suspension was then vortexed and incubated for 30 seconds at room temperature.

They performed an endpoint dilution assay on Vero 76 cells and assessed CPE microscopically after seven days. Next, they calculated the 50% tissue culture infective dose (ID50) per milliliter for all four disinfectants at final concentrations of 20%, 30%, 40%, 60%. and 80%. Finally, the researchers examined the virucidal activity of WHO formulations I and II against MPXV in a suspension test.

Study results

MPXV showed sensitivity to both WHO formulations, but was also the most stable among all viruses tested, including the modified vaccinia Ankara. Both formulations efficiently inactivated MPXV with reduction factors (RFs) >6.7 at concentrations of 60% and 80% volume/volume (v/v). Remarkably, WHO Formulation II remained effective against MPXV even at a dilution of 40% (vol/vol) with an RF of 6.6. Conversely, WHO formulation I failed to reduce MPXV titers at a similar concentration.

The researchers found that both ethanol and 2-propanol reduced MPXV titers to background levels with RFs >6.7 at >60% and >40% (v/v) concentrations, respectively. At RF = 6.6, 40% ethanol (v/v) almost completely inactivated MPXV. However, at RF = 5.3, 30% v/v 2-propanol achieved the same virucidal activity.

Conclusions

Overall, the study results showed that MPXV showed the highest stability to both WHO formulations compared to other (re)emerging viruses of the Orthopox family. Infectious MPXV persists in a household environment for more than 15 days. Due to tight binding with fibrin matrices from eschar material, virions shed from lesions are even more resistant to desiccation than other enveloped viruses (e.g., influenza virus). The high stability of MPXV requires a comprehensive reassessment of current hygiene measures. Fortunately, both WHO formulations tested effectively inactivated MPXV, supporting their use in healthcare systems and during MPXV outbreaks. In conclusion, the study demonstrated that timely application of alcohol-based disinfectants could effectively minimize the spread of MPXV during the ongoing MPVX outbreak.

Reference:

• Meister TL, Tao R, Brüggemann Y, Todt D, Steinmann J, Timm J, et al. (2022). Effiziente Inaktivierung des Affenpockenvirus durch von der Weltgesundheitsorganisation empfohlene Händedesinfektionsformulierungen und Alkohole. Neu auftretende Infektionskrankheiten. doi: https://doi.org/10.3201/eid2901.221429 https://wwwnc.cdc.gov/eid/article/29/1/22-1429_article

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