Alcohol-free hand sanitizer completely inactivates SARS-CoV-2 in 15 secs

Alcohol-free hand sanitizers containing quaternary ammonium compound (quat) completely inactivate SARS-CoV-2 virus within 15 seconds, even with soil load or when diluted in hard water, a study finds — providing a useful alternative to alcohol-based disinfectants.

“Our results indicate that alcohol-free hand sanitizer works just as well, so we could, maybe even should, be using it to control COVID,” said lead author Benjamin Ogilvie, a graduate student at Brigham Young University in Provo, Utah, US.

The researchers tested three commercially available disinfectants containing quat and one laboratory-made solution of 0.2% benzalkonium chloride. The three commercial products were Cavicide (a quat hospital disinfectant), Clean Quick Broad Range Quaternary Sanitizer (a multipurpose quat disinfectant for food contact surfaces), and fluid from Qimei® Hand Sanitizing Wipes containing benzalkonium chloride. A suspension test method was performed and live virus assayed using a plaque assay.

All sanitizers, except Clean Quick, effectively inactivated SARS-CoV-2 virus within 15 seconds, regardless of whether a soil load of 5% BSA or 0.5% mucin was present or not. [J Hosp Infect 2020;doi:10.1016/j.jhin.2020.11.023]

Solution of 0.2% benzalkonium chloride remained effective even when diluted in hard water (viral titre reduction, >3.19 log₁₀ PFU*/mL). The other three commercial products were not tested for dilution in hard water as they were sold ready to use.

“These variables were designed to simulate real-world conditions: in practice, surfaces contaminated with SARS-CoV-2 likely contain mucus or other organic materials, and water used to dilute disinfectants may contain hard water ions,” explained Ogilvie and co-authors.

“Quat compounds, in particular, are known to vary in activity with changes in disinfectant formulation or soil load, so accounting for these factors in laboratory tests is especially important,” they added.

Nonetheless, Clean Quick was effective in viral inactivation after 30 seconds of contact, in the absence of soil load — in line with its intended use as “non-rinse sanitizer for third-sink sanitizing of dishes” or for precleaned surfaces, with a contact time of ≥1 minute.

“Perhaps the most significant finding of this study is that benzalkonium chloride hand sanitizer is effective at inactivating SARS-CoV-2, which is useful for healthcare professionals to know,” the researchers pointed out.

“Benzalkonium chloride can be used in much lower concentrations and does not cause the familiar ‘burn’ feeling you might know from using alcohol hand sanitizer. It can make life easier for people who have to sanitize hands a lot, like healthcare workers, and maybe even increase compliance with sanitizing guidelines,” said Ogilvie.

The availability of effective alternatives to alcohol-based products can help relieve the shortages that so overwhelmed the US and elsewhere, especially during early stages of the pandemic.

“Beyond merely inactivating the virus, quats act quickly, making them practical for use in healthcare settings where prompt disinfection is important,” Ogilvie highlighted.

*PFU: plaque-forming unit