These are very early days in terms of our understanding of the Omicron variant. What is known is that it has a large number of mutations, particularly in the spike protein and it appears to be rapidly spreading in specific parts of the world.

Very early indications from Africa suggest it does not cause particularly severe disease (though the World Health Organization has urged caution given the limited data available).

At this point, it is not clear whether it has any greater capacity to evade vaccines than other SARS-CoV-2 strains such as Delta.

It is very common for viruses to become less virulent (that is, cause less severe disease) once they become established in a population. The classic example is myxomatosis, which killed 99% of rabbits when first introduced into Australia, but now causes much lower mortality.

Some experts have predicted Covid-19 will also become less severe as it transitions to an endemic level of disease – settling into a predictable pattern of infections in a given location. It is possible the Omicron variant may be the first step in this process.

Dominant variants

Evolutionary biology suggests variants are more likely to thrive if they increase more rapidly in the human population than current strains. This means two things: strains with a higher R number (the basic reproduction number, or the…

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