Moscow, Jan 31 : An individual infected with Omicron can spread the infection within hours, according to an expert. On the other hand, infections spread with previous strains in three to four days, TASS news agency quoted Alexander Semyonov, head of the Yekaterinburg branch of the Vector State Research Center of Virology and Biotechnology, as saying. "The saddest thing is due to its rapid replication, you can communicate the virus not in three to four days but already by the evening," he said in an interview with the Rossiya-1 television channel. At the same time, he said, Omicron is cleared from the body in about a week, or much faster than other strains. According to a study led by researchers at the University of Hong Kong, Omicron spreads 70 times faster than Delta variant. On November 26, the World Health Organisation (WHO) designated the B.1.1.529 variant identified in South Africa as a "Variant of Concern" and assigned it the Greek letter Omicron. In its statement, the WHO noted that "this variant has a large number of mutations, some of which are concerning". So far it has spread to more than 120 countries, outpacing the previous Delta variant to become the dominant one. While it has surged infections in many countries, the infections are generally touted as mild, leading to less hospitalisation as well as deaths compared to Delta. Meanwhile, the Hong Kong study also showed that Omicron's replication rate in human lung tissue was more than 10 times lower than what was seen with the original strain -- an observation that "may suggest lower severity of diseasea. /IANS