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Some global lessons from Omicron already clear: quick surveillance and vaccine equity

- Shahid Jameel

Following news of a new Covid-19 virus variant, fresh travel bans and restrictions are being put in place in several countries. There are also calls for booster vaccinations in several countries, including those that are yet to fully vaccinate a majority of their people. All these are emotional responses driven by the fear of another variant virus spreading at a time when economies are recovering, and the world is looking forward to some holiday cheer.

What do we know about this emerging variant named Omicron by WHO, also called the B.1.1.529 lineage? Scientists first saw a heavily mutated Covid-19 virus variant, in samples from South Africa and Botswana. The Omicron variant shows 50 mutations – twice as many as the Delta variant – including 32 in the spike protein, which is the target of all available vaccines. A key region of this protein called the receptor-binding domain, which the virus uses to enter cells, carries 10 mutations compared to just two in Delta.

The Omicron variant has several mutations that may allow it to resist neutralising antibodies developed following an infection or vaccination, and therapeutic monoclonal antibodies. It also has a cluster of mutations around the S1/S2 cleavage site in the spike protein, which is associated with entry into cells. More efficient entry often translates into more virus production and increased transmissibility. Mutations in other parts of the virus may also indirectly increase its transmissibility.

All this is based on our knowledge of similar mutations in other variants. How two or more mutations will combine to change the behavior of a virus is not easily predictable.