Nine hours. This is the time when the coronavirus can survive on our skin. This is demonstrated by researchers from the Kyoto Prefectural University of Medicine in Japan, who in their new study observed how Sars-Cov-2 manages to survive on human skin for a significantly longer period of time than influenza viruses . For this reason, the researchers underline, it is essential to respect one of the first and most important strategies put in place to contain the spread of coronaviurs, namely that of washing hands frequently with soap and water . The study was published on the pages of the journal Clinical Infectious Diseases.
Since the beginning of the pandemic , one of the goals we have set ourselves has been precisely to understand how long the coronavirus managed to survive on surfaces . As we told you, for example, a study has shown that the virus can persist from a few minutes to days and hours depending on the type of material on which it is deposited: on copper up to 4 hours, on cardboard up to a day, while on plastic and steel for up to three days. In a table published by the Ministry of Health, it has been estimated that the coronavirus can survive on printing paper for half an hour, one day on textiles and wood and two days on banknotes and glasses.
So far, however, for ethical reasons, we have not been able to estimate the survival time of the coronavirus on human skin : it would be really dangerous to use samples of a potentially lethal virus for example on people’s hands. To get around this, the researchers in the new study conducted some experiments using skin samples from people who died the day before. Even 24 hours after death, the authors note, the skin can still be used for skin grafts, meaning that it retains most of its functions for that period of time. The analyzes showed that Sars-Cov-2 remained active for about 9 hours , while a strain of influenza A virus for a couple of hours or so. Furthermore, when the researchers mixed the viral particles with substances to simulate a cough or sneeze, they observed that the coronavirus managed to persist for a full 11 hours .
Both viruses, however, were quickly inactivated thanks to common hand disinfectants (those with a percentage of ethanol equal to 80%): once applied to the skin, in fact, the pathogens were eliminated in about 15 seconds . “The study shows that Sars-Cov-2 may have a higher risk of transmission by direct contact than the flu virus because it is much more stable on human skin,” the study reads. “These results confirm once again that proper hand hygiene is important for the prevention of the spread of the coronavirus. “It should be noted, however, that the study has some limitations: as the authors themselves explain, in fact, the “infectious dose” of the coronavirus, or the amount of viral particles necessary to infect someone through direct contact with infected skin, was not considered. This, the researchers conclude, will be their next goal.