Each Omicron wave so far in Australia has had distinguishing features — the sharp rise and fall of BA.1, the widespread transmission among children and families in BA.2, a shift to more infections in older people with BA.5, then the confusing variant mix in the summer wave of 2022-23.

Now Australia is in its fifth Omicron wave, which has been brewing since February. But it has grown so slowly that many people may have not realised it until recent months.