The researchers attempted to answer how, when, and where the Omicron variant of SARS-CoV-2 emerged, according to a study published in the journal Science. In their study, they noted that the predecessors of the Omicron subvariants existed on the African continent long before cases were first identified. The study implied that Omicron emerged gradually over several months in different countries across Africa.

The researchers from the Charite- Universitatsmedizin Berlin stated that the coronavirus had evolved since the pandemics beginning. But the biggest leap in evolution was observed when a variant was discovered that differed from the genome of the original virus by more than 50 mutations a year ago.

The first Omicron case, later named Omicron BA.1, was detected in South Africa in November 2021. However, by the end of December, the global population was dealing with the dominant delta variant. Based on this trend, two theories about the transmission of the variants were hypothesized, i.e., either the coronavirus jumped from a human to an animal, where it evolved before infecting a human again as Omicron, or the virus survived in a person with a compromised immune system for a longer period and mutations occurred there.

However, an international study conducted by Stellenbosch University in South Africa and the Laboratory of Viral Hemorrhagic Fever (LFHB) in Benin contradicted these two speculations. The researchers found viruses with Omicron-specific mutations in 25 people from six different countries who contracted COVID-19 in August and September 2021.

On decoding the genome of the viral samples, the team found that the viruses showed varying degrees of similarity to Omicron but were not identical. Hence, the second study suggested that the BA.1 Omicron variant evolved gradually while slowly adapting to the existing human immune system. 

(Source: https://health.economictimes.indiatimes.com/news/diagnostics/study-sheds-light-on-origins-of-omicron-virus/95979321 )