Other topical disinfectants can also be used to inactivate coronaviruses from surfaces, including the skin. A recently published analysis of 22 studies found that human coronaviruses – such as severe acute respiratory syndrome (SARS) coronavirus, Middle East respiratory syndrome (MERS) coronavirus, or endemic human coronaviruses (HCoV) – can persist on inanimate surfaces such as metal, glass, or plastic for up to 9 days (COVID-19 was found in a study to persist on metal for up to 2-3 days), but can be efficiently inactivated by surface disinfection procedures with 62%-71% ethanol, 0.5% hydrogen peroxide, or 0.1% sodium hypochlorite within 1 minute. Other biocidal agents, such as 0.05%-0.2% benzalkonium chloride or 0.02% chlorhexidine digluconate, are less effective.
Dr. Lily Talakoub
In the case of SARS, treatment of SARS-CoV with povidone-iodine products for 2 minutes reduced virus infectivity to below the detectable level, equivalent to the effect of ethanol, in one study. Formalin fixation of the infected cells and heating the virus to 56° C, as used in routine tissue processing, were found to inactivate several coronaviruses as well. Based on this information, ethanol-based hand sanitizers, typically containing ethanol content of 60% or higher, can be used to inactivate coronaviruses on the skin, including COVID-19.
In patients with influenza-virus infections, whether pathogens were in wet or dried mucus played a role in whether hand washing or rubbing with hand sanitizer was more effective. In a study that examined the effects of hand washing versus antiseptic hand rubbing with an ethanol-based hand disinfectant on inactivation of influenza A virus adhered to the hands, the investigators showed that the effectiveness of the ethanol-based disinfectant against influenza A virus in mucus was reduced, compared with influenza A virus in saline. Influenza A in mucus remained active, despite 120 seconds of hand rubbing with hand sanitizer; however, influenza A in saline was completely inactivated within 30 seconds. Interestingly, rubbing hands with an ethanol-based disinfectant inactivated influenza A virus in mucus within 30 seconds with mucus that had dried completely because the hydrogel characteristics had been eliminated. Hand washing rapidly inactivated influenza A virus whether in mucus form, saline, or dried mucous.
It is important to note that in COVID-19 infections, a productive cough or rhinorrhea are not as common compared with dry cough. Regardless, the findings of the study described above should be considered if mucous symptoms develop during a COVID-19 infection when determining infection control. Luckily, with COVID-19, both hand washing and use of an ethanol-based hand sanitizer are seemingly effective in inactivating the virus or removing it from the skin surface.
After frequent hand washing, we all can experience dryness and potentially cracked skin as well. With hand sanitizer, the alcohol content can also cause burning of skin, especially compromised skin.
Vanilloid receptor-1 (VR1), a heat-gated ion channel, is responsible for the burning sensation caused by capsaicin. Ethanol lowers the amount of heat needed to turn on VR1 nocioceptive pain receptors by almost ten degrees, resulting in a potential burning sensation when applied.
Nails are affected as well with frequent hand washing and/or application of hand sanitizer and can become cracked or brittle. Contact dermatitis, both irritant and allergic, can occur with increased use of disinfectants, particularly household cleaners without proper barrier protection.