New Covid-19 subvariants are driving an increase in cases overseas, Newshub reports, and an expert said it is “increasingly likely” the wave could travel to New Zealand this year. World Health Organization (WHO) officials said hundreds of new forms of Omicron are being tracked by scientists. Waning immunity could also be playing a role in the uptick in cases overseas as time ticks over since many people’s last COVID-19 vaccine and infection. Meanwhile, overseas scientists have said there are signs the emerging Omicron sub-variants could be evolving to dodge immunity.