Research results that influenza virus attached with saliva is invincible for 4 minutes against alcohol disinfection


by Phovoir

Alcohol disinfectants are installed at the entrances of public institutions, supermarkets, restaurants, etc., so that you can clean your hands with a single push of the pump. However, the latest research focusing on the physical properties of mucus reports that influenza viruses are protected by saliva and therefore almost never die by alcohol disinfection.

Situations Leading to Reduced Effectiveness of Current Hand Hygiene against Infectious Mucus from Influenza Virus-Infected Patients | mSphere
https://msphere.asm.org/content/4/5/e00474-19

Identification of situations in which the effectiveness of current hand hygiene decreases for infectious mucus from influenza-infected patients
(PDF file) http://www.kpu-m.ac.jp/doc/news/2019/files/21731.pdf

Past research has confirmed that 'organic substances in body fluids weaken the disinfection action of ethanol.' Disinfectants that meet standards based on these findings are used in medical practice. However, there has been no research that has focused on the “physical properties of infectious mucus” such as saliva that mediates contact infection and droplet infection .

by Elegant01

Therefore, the research group of Ryohei Hirose, an assistant professor at Kyoto Prefectural University of Medicine, collected infectious mucus (acupuncture) as a sample from 52 patients diagnosed with acute upper respiratory tract infection called so-called cold syndrome . The viscosity of the mucus was examined by measuring the shear rate of 19 samples that were actually confirmed to contain influenza virus.

After that, by fluid simulation, the time until the virus lost its infectivity when the alcohol-containing liquid was applied to the liquid containing the virus was examined. As a result, the time required for the virus contained in mucus to become inactive was 8 times longer than that of physiological saline. The figure below explains the mechanism. Infectious mucus has a higher viscosity as a gel and is much less likely to mix with disinfectant compared to water, so the concentration of disinfectant increases more slowly, and as a result, the disinfectant is effective against viruses. The time will be greatly increased.


In order to verify the simulation results, the research group worked with 10 volunteers to conduct a clinical experiment to investigate the time it took for the influenza virus attached to the hand to lose its infectivity due to the disinfectant. As a result, the influenza virus in saline was completely inactivated 30 seconds after disinfecting the hands with a disinfectant, while the influenza virus in mucus was finally inactivated after 240 seconds, that is, 4 minutes. It was said that it was done.

The research group also conducted additional simulations based on the results of clinical experiments to investigate the behavior of mucus containing viruses in contact with disinfectants. The upper part A is when using physiological saline, and the part where the red virus was activated disappeared 30 seconds after the light blue disinfectant was dropped. On the other hand, in the lower B, 240 seconds in the previous experiment resulted in an unrealistic result for alcohol disinfection, so the simulation was performed with a liquid with only 16.7% actual viscosity. Still, it takes 60 seconds, twice the amount of saline, until the red part disappears.


From this result, the research group concludes that `` even with proper hand sanitization with alcohol disinfectants, pathogens that maintained infectivity remained on the body surface and there was a risk of spreading infection. '' It is attached.

On the other hand, if the mucus is in a dry state, the disinfectant has been found to be effective, and the time required for the virus in the dried mucus to be inactivated by the disinfectant was 30 seconds. However, even with only 5 microliters of mucus, it takes about 30 minutes to dry completely in an indoor environment with a temperature of 25 degrees and humidity of 40%. Is still not realistic.

Therefore, when the research group conducted an experiment to physically remove mucus with running water, the mucus disappeared in 30 seconds and the infectivity of the virus disappeared. Removing with running water is basically hand-washing, but in the experiment, soap was not used, but only pure water was used, so washing hands with soap would be more effective.

by DragonImages

According to the research group, “Alcohol hand hygiene, which is said to be able to prevent infection quickly and easily, is not used because it is not possible to secure sufficient time between seeing one patient and the next. But now that we know that the current prevention methods are inadequate, we can't help but say that the effectiveness of alcohol hand hygiene is minimal. ' He expressed his view that the development of more effective disinfectants and disinfection methods is urgent.

in Note, Posted by log1l_ks