The Omicron COVID-19 variant can survive longer than earlier strains of the virus on plastic surfaces and human skin, new research by Japanese scientists has found.
The study by a team from the Kyoto Prefectural University of Medicine, which is not yet peer reviewed, found that the variants survived much longer than the original strain following a series of laboratory tests.
They concluded that Omicron’s high "environmental stability" - its ability to remain infectious - in particular might have helped it replace Delta as the dominant variant and spread more rapidly.
“Our study showed that on plastic and skin surfaces, Alpha, Beta, Delta, and Omicron variants exhibited more than two-fold longer survival times than those of the Wuhan strain and maintained infectivity for more than 16 h on the skin surfaces,” the study’s authors wrote.
On plastic surfaces, average survival times of the original strain and the Alpha, Beta, Gamma and Delta variants were 56 hours, 191.3 hours, 156.6 hours, 59.3 hours, and 114 hours respectively.
That compared to 193.5 hours - the equivalent of eight days - for Omicron, the researchers reported on bioRxiv ahead of peer review.
Omicron lasts for over 21 hours on skin
On skin samples from cadavers, average virus survival times were 8.6 hours for the original version, 19.6 hours for Alpha, 19.1 hours for Beta, 11 hours Gamma, 16.8 hours for Delta and 21.1 hours for Omicron.
“This study showed that the Omicron variant also has the highest environmental stability among VOCs [variants of concern], which suggests that this high stability might also be one of the factors that have allowed the Omicron variant to replace the Delta variant and spread rapidly,” the authors wrote.
Continuing to be a major concern around the world, Omicron is now present in all EU countries and has become the dominant variant in the majority of member states, according to the European Centre for Disease Prevention and Control (ECDC).
The countries where the highest percentage of new cases were attributed to Omicron through sequencing were Finland (99.9 per cent), Belgium (99.7 per cent), Malta (99.3 per cent) and Denmark (98.8 per cent).
Although the variants were generally more resistant to ethanol than the original strain of COVID-19, all of them were completely inactivated on skin after 15 seconds of exposure to alcohol-based hand sanitizers.
"Therefore," the researchers concluded, "it is highly recommended that current infection control (hand hygiene) practices use disinfectants... as proposed by the World Health Organization [WHO]".