Commentary: Do Omicron’s many sub-variants mean the virus is mutating faster?

Alarmingly, even if someone has been infected with the Omicron sub-variant BA.1, reinfection is still possible with sub-lineages of BA.2, BA.4 and BA.5 due to their capacity to evade immune responses.


You’d think SARS-CoV-2 is a super-speedy front-runner when it comes to mutations. But the virus actually mutates relatively slowly. Influenza viruses, for example, mutate at least four times faster.

SARS-CoV-2 does, however, have “mutational sprints” for short periods of time, our research shows. During one of these sprints, the virus can mutate four-fold faster than normal for a few weeks.

After such sprints, the lineage has more mutations, some of which may provide an advantage over other lineages. Examples include mutations that can help the virus become more transmissible, cause more severe disease, or evade our immune response, and thus we have new variants emerging.

Why the virus undergoes mutational sprints that lead to the emergence of variants is unclear. But there are two main theories about the origins of Omicron and how it accumulated so many mutations.

First, the virus could have evolved in chronic (prolonged) infections in people who are immunosuppressed (have a weakened immune system).

Second, the virus could have “jumped” to another species, before infecting humans again.


Mutation is not the only way variants can emerge. The Omicron XE variant appears to have resulted from a recombination event. This is where a single patient was infected with BA.1 and BA.2 at the same time. This coinfection led to a “genome swap” and a hybrid variant.