Sub-variants of Omicron are so infectious it doesn't matter if it's winter or summer, Professor Michael Baker says. Photo: University of Otago Wellington / Luke Pilkinton-Ching
A third wave of the Omicron variant of Covid-19 is likely to hit the country this year, Professor Michael Baker says.
Covid-19 cases are on the rise again with over 16,000 cases reported over the past week - an increase of about 2000 cases in a week.
Waitematā, Auckland and Counties Manukau have reported almost 6000 cases in the city alone.
As well, as of midnight on Monday, there were 243 people in hospital with the virus, with six in intensive care.
Professor Baker, who is an epidemiologist at Otago University, said there had been two big waves of Omicron this year and there looked like being a third one but it was unknown at this stage how big it would be.
He said Singapore, whose experience of the pandemic has been similar to New Zealand's, was also experiencing a steady rise.
"That may be what we'll see here."
Two new names have become prominent - the BQ.1.1 was a sub-variant while XBB was a recombinant variant which had grabbed genetic material from two other sub-variants. The latter was driving Singapore's surge, Baker said.
Both were on the country's watchlist and have been detected in some cases and in wastewater in New Zealand.
While the country was heading into summer, the time of year did not affect the sub-variants because they were so infectious, he said.
"So they get a bit of a boost from winter when people are indoors more but they don't absolutely need winter conditions to spread."
He said it was "slightly worrying" to see cruise ships back in New Zealand waters with about 130 infected people on one ship that has berthed at Wellington.
However, with open borders and 10,000 people flying in daily from overseas, cases on cruise ships would be a small contribution to the country's Covid-19 case tally.
Baker was concerned that many adults had not lined up for their booster shots.
"So that's really a critical step and that's still the best measure that people can take to protect themselves and it does help against these new variants as well."
"[Sub-variants] don't absolutely need winter conditions to spread" - Epidemiologist Professor Michael Baker