Last update and review: April 25, 2020.
There are questions regarding the effectiveness of different disinfectants against the SARS-CoV-2 virus that causes COVID-19.
Below, there is an excerpt from a piece of research on a very similar virus, SARS-CoV-1, that caused the SARS epidemic in 2002-2004.
In 30 seconds of exposure, a hand disinfectant based on 80% ethanol inactivated the SARS-CoV-1 virus to a level below the limit of detection.
After an exposure of the virus to the disinfectants, the researchers attempted to cultivate viruses in a cell culture. This is the appropriate procedure to assess virus infectivity. Indeed, just detecting the presence of a virus RNA in a sample does not inform us if the virus is active and capable to infect.
Here is how Rabenau et al., 2004 (1) describe their procedure:
Susceptibility of SARS-CoV to different chemical disinfectants
The experiments were performed according to prEN 14476.19 For each of the experiments, eight parts of the compound were adapted to room temperature (RT) and mixed with one part of virus suspension and one part of organic load or MEM. The organic loads used were 0.3% albumin, 10% FCS, and 0.3% albumin with 0.3% sheep erythrocytes. Immediately after incubation for defined periods of time at RT, the mixture was diluted 1:10 with ice-cold MEM and put into an ice bath to avoid an extension of the effective incubation period. Serial 10-fold dilutions with ice-cold MEM were performed to assess virus titres as described above. For each dilution step, eight wells containing suspended cells were inoculated. After three to four days of incubation at 37 °C in an CO2 incubator, cells were microscopically examined for virus-specific cytopathogenic effects. All tests were performed in triplicate, and for each experiment, a virus control containing MEM instead of disinfectant was included (‘control titration’). Further control experiments included formaldehyde (0.7%) as standard disinfectant, and a ‘termination control’, which is a 1:10 dilution of the disinfectant. This control demonstrates the first 1:10 dilution step in the above mentioned procedure and should verify if a postincubation effect of the disinfectant exists. Furthermore, cytotoxic effects caused by the compounds at various dilutions were assessed in suspended Vero cells in 96-well plates using the MTT Cell Proliferative Kit I (Roche, Mannheim, Germany) as published previously.20, 21 Tests for cytotoxicity were performed as single assays using 10% FCS and disinfectant but without addition of virus.
The “Reduction factor” used by the researchers to estimate the inactivation of the virus is somewhat confusing.
The researchers (1) used “Reduction factor” to estimate the inactivation of the virus. This parameter is somewhat confusing:
Calculation of the reduction factor
The reduction factor (RF) was calculated as the difference in the quotient of the infection titre before (‘control titration’) and after incubation of the virus with the disinfectant (‘remaining virus’). Therefore, the log10 titre and its (double) standard deviation (SD) were calculated as well as the variance of the RF.
The conclusions of the researchers (1) are that a disinfectant with 80% ethanol effectively inactivated the SARS-CoV-1 virus in 30 seconds. Other disinfectants were also effective but the required time was different for different agents:
SARS-CoV was inactivated to below the limit of detection (reduction factor mostly ≥4), regardless of the type of organic load. In summary, SARS-CoV can be inactivated quite easily with many commonly used disinfectants.
Conclusion: do use ethanol to deactivate the SARS-CoV-2 virus.
During the COVID-19 epidemic, disinfecting the objects that you use outside of your home, for instance, your phone, is a smart thing to do. 80% alcohol is one of the possible disinfectant to use.
Important things not to do.
During the COVID-19 epidemic and regardless of any epidemic, there are also dumb things to do and there are criminal things to do. For instance, injecting yourself with vaccines that are very unlikely to provide any protection is dumb. Accepting “immunity passports” proposed by many idiotic criminal bureaucrats is an act of collaboration with a Nazi-style madness. Resist crazy bureaucrats at all times, do not collaborate. Ideology: “Nazism” starts when the masses become collaborators to a small group of mad criminals. Collaborating with criminals makes you a criminal as well.
A Test of Physiological Literacy.
1. Does ultraviolet light deactivate SARS-CoV-1 or SARS-CoV-2 viruses?
Selected references:
1. Rabenau HF, Kampf G, Cinatl J, Doerr HW. Efficacy of various disinfectants against SARS coronavirus. J Hosp Infect. 2005;61(2):107–111. doi:10.1016/j.jhin.2004.12.023
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