伏特加酒(或濃度低於60%的酒精溶液)是否是針對Covid-19的有效洗手液?


43

在某些地方,很多人都堅持要求洗手液的酒精含量必須超過60%,即使是針對新的冠狀病毒,也是如此。伏特加酒(通常濃度較低)將無效,e.g.

Almost as soon as the news broke about COVID-19 (the official name for the illness caused by the virus), conspiracy theories, hoaxes, and misinformation spread like wildfire online — even from some traditionally reputable information sources. [...] Here are seven myths or hoaxes that we found, and what the reality is.

MYTH: If you can’t get hand sanitizer, you can make your own with vodka.

REALITY: Thanks to several social media posts, including one originally linked to Good Housekeeping, Tito’s Handmade Vodka has spent two days on Twitter telling people, individually, not to use their vodka to make hand sanitizer.

“Per the CDC, hand sanitizer needs to contain at least 60 percent alcohol. Tito’s Handmade Vodka is 40 percent alcohol, and therefore does not meet the current recommendation of the CDC,” Tito’s tweets say.

41

A more recent study (also published by the CDC) seems to indicate that 30% might be a good enough concentration against SARS-CoV-2:

enter image description here

[Figure legend:] Effect of commercially available alcohols in inactivating SARS-CoV-2. The means of 3 independent experiments with SDs (error bars) are shown. A) Results for ethanol. B) Results for 2-propanol. Dark gray bar indicates cytotoxic effects, calculated analogous to virus infectivity. Dashed line represents limit of detection. Reduction factors are included above the bar. The biocide concentrations ranged from 0–80% with an exposure time of 30 s. Viral titers are displayed as TCID50/mL values. LLOQ, lower limit of quantification; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; TCID50/mL, 50% tissue culture infectious dose.

[...] Conclusions: [...] ethanol and 2-propanol were efficient in inactivating the virus in 30 s at a concentration of >30% (vol/vol). Alcohol constitutes the basis for many hand rubs routinely used in healthcare settings. One caveat of this study is the defined inactivation time of exactly 30 s, which is the time recommended but not routinely performed in practice.

Having said this, antiseptics and disinfectants (in general) are binned in roughly 3 categories based on what they can deal with. Mycobacteria (e.g. tuberculosis) and bacterial spores are a harder (and respectively a lot harder) to inactivate/kill than viruses. (Some antiseptics were even contaminated with mycobacteria.) So (besides possible non-compliance with the recommended use/rubbing time) this is a good reason to demand greater alcohol concentration in general-purpose alcohol-based antiseptics.

Furthermore, even just a far as alcohol effectiveness against viruses is concerned, a 2019 Japanese study of influenza A virus (IAV) inactivation by ethanol found that [non-dry] mucus constituted an extra protective layer for the virus (besides its own envelope), slowing the effect of ethanol-based disinfectants (EBDs) about eight times:

Our clinical study showed that EBD effectiveness against IAV in mucus was extremely reduced compared to IAV in saline. IAV in mucus remained active despite 120 s of AHR [antiseptic hand rubbing]; however, IAV in saline was completely inactivated within 30 s. Due to the low rate of diffusion/convection because of the physical properties of mucus as a hydrogel, the time required for the ethanol concentration to reach an IAV inactivation level and thus for EBDs to completely inactivate IAV was approximately eight times longer in mucus than in saline. On the other hand, AHR inactivated IAV in mucus within 30 s when the mucus dried completely because the hydrogel characteristics were lost.

(30s is the hand-rubbing typically recommended for antiseptics when used as hand sanitizers.)