Viruses are structural infectious agents that contain genetic material like DNA or RNA. Viruses are encapsulated and protected by a protein envelope known as capsid. Viruses are further categorized as “enveloped” or “unenveloped.” Apart from the structural elements, it also contains a host cell which helps in propagation of viruses [11]. A common compound in virucides is N-Propanol. It is believed that it damages the membrane of the virus and it affects its decoupling and protein synthesis. For effective virucidal efficacy concentrations of not less than 60% and not more than 90% is enough. Alcohol that contains not more than 1% water is less virucidal than alcohol in the ranges mentioned above. Therefore, water is essential in the process of protein denaturation. Regardless of what processes alcohol affects, if not many, it eventually results in primary metabolic pathways, damage to the cell membrane, and loss of cell integrity. Alcohol-based hand sanitizers target the cover that protects the components of the virus. All the components are very critical for the virus. Therefore, it is assumed that after one of the components is targeted it may lose its ability to transfer from one host to another. This mechanism is compared to bacteria; it is observed that ethanol’s virucidal effect when compared to propanol is more effective against viruses of clinical relevance. It is also worth noting that in cases where only ethanol is not as effective against the viruses, adding acids can improve ethanol’s performance [12].
The SARS-CoV-2 virus was named because its genome sequence is similar to that of the SARS coronavirus (SARS-CoV) [13, 14]. CoV is related to the same gene beta coronavirus and has the same morphology as the single-stranded RNA virus [15, 16]. Ethyl alcohol at a concentration of 60 to 80% is a potent agent that inactivates all lipophilic viruses (such as influenza virus, herpes, and vaccinia and many hydrophilic viruses (e.g., polio) [17].
The WHO in 2015 recommended 80% concentration of ethanol and 75% concentration of isopropyl alcohol for “disinfectant: alcohol-based hand sanitizer” [18]. Ethanol seems to be more effective against bacteria than isopropanol and N-propanol. WHO also recommended that alcohol-based disinfectants showed results against emerging viruses too for example Zika, Ebola, and MERS [19, 20]. Another study showed that a little over 42.5% concentration of ethanol was able to destroy coronavirus in about thirty seconds [21].
It is harder to study viruses than bacteria. Many studies have tried to test the efficacy of hand sanitizers on viruses. Use of alcohol-based hand sanitizers are recommended by WHO for protection against multiple viruses including the coronavirus as it has proven effective in quantitative suspension testing [19]. Other sterile sources containing isopropyl alcohol as the main ingredient also have proven effective against multiple enveloped viruses [17].
Studies have been conducted in which viruses have been externally applied or put-on fingers and hand sanitizers have successfully reduced the viral particles [22, 23]. Ethanol have been shown to be highly effectual against germs and most hospital-related viruses [24, 25]. Seventy to 80% alcohol concentration was enough for reliable inactivation in multiple viruses. Adequate activities can be attained with prolonged contact with the concentration of alcohol over time and prolonged contact with undiscovered virus.
A review of the literature on the effectiveness of handwashing against severe acute respiratory syndrome (SARS) transmission found that nine out of 10 small case-control studies showed that hand washing reduced the risk of social contamination [26]. Vivo evidence of viral inactivity after the use of hand sanitizers is not available by standard methods. Vitro studies have established that alcohol-based disinfectants can be effectual in reducing viral load [8].
The SARS-CoV-2 transmission has an incubation time of 10 days, which makes it easy to propagate through drops, contaminated hands or surfaces. Therefore, the effect of viral inactivity on all broadcasts should be considered [27]. Alcoholic disinfectants have been able to deactivate SARS-CoV-2 and MERS-CoV (also pre-activated coronaviruses) on living surfaces like plastic, glass, and metal [28]. A key limitation in analyzing the actual performance of hand disinfection is the recurring process of self-reported data gathering, which may not be the same and objective in terms of the frequency and method of hand washing [26].