What are Omicron's origins? Scientists point out key theories
The Omicron variant of Covid-19, which is currently the dominant strain of the coronavirus in many countries, has led to a sharp surge in infections. Even though Omicron is believed to be less severe than the previous Delta variant, its ability to spread very quickly has strained the health infrastructure of many countries.
One of the most important questions that would pop into the minds of people is from where did Omicron (B.1.1.529) actually originate.
It is widely believed that Omicron was first detected in South Africa in November 2021 and spread to all other countries faster than any other variant of Covid-19 seen till now.
However, there are more key theories regarding the origin of this fast-spreading variant.
According to a report by Nature, evolutionary virologists have evaluated that the closest-known genetic ancestor of Omicron probably dates back to after mid-2020.
Ahead of the World Health Organization's (WHO's) report on the origins of Omicron, another theory emerged that even though scientists sequenced millions of SARS-CoV-2 genomes, they might have missed a series of mutations that eventually led to the variant, the report said. It added that Omicron could have also emerged 'unseen' in animal hosts such as rats or mice.
An important point to note is that Omicron has over 50 mutations compared to the original SARS-CoV-2. Thirty of these mutations are involved in changes in amino acids in Covid-19's spike protein, which the virus uses to attach to and fuse with cells. The above report also said that previous variants of concern did not have more than 10 spike mutations.
Another theory which Nature’s report said that Omicron comprises three sub-lineages- BA.1, BA.2 and BA.3. Of these, BA.1 and BA.2 have already started spreading globally. This implied that the variant had time to diversify before scientists could notice it, the report added.
The WHO has warned that despite Omicron having milder symptoms, the number of people unvaccinated against Covid-19 is helping to drive the variant's transmission. The United Nations health body has also said that Omicron will be the last variant of Covid-19.