There are warnings new COVID-19 variants arriving in New Zealand could create a wave of cases.
Modelling by The Institute of Environmental Science and Research (ESR) suggests the BA.5 Omicron variant could overtake BA.2 as the dominant strain of COVID-19 in New Zealand by late July.
The modelling also predicts BA.5 could make up more than half of daily infections in as little as two weeks.
While BA.5 is not thought to be more severe than other variants of Omicron, it is better at evading immunity from previous infections and vaccinations.
It comes after new COVID-19 cases shot up on Tuesday to 8028 with 16 more deaths, including a teenager.
The seven-day rolling average is also starting to track upwards with about 600 more cases a day at the moment compared to last week.
Epidemiologist Michael Baker told Newshub there are several reasons cases are increasing.
"It's very early to predict a trend, but we certainly have seen a slight rise in cases over the last week," Baker said.
"The pandemic is very much gnawing away at us and creating this quite high health burden. Certainly, most factors are actually favouring the virus now and that is that our immunity is waning, we're getting more infectious variants arriving in New Zealand and also we have relaxed some of our controls and of course, we're in winter, we're indoors a lot more and these conditions do favour the virus," he said.
Baker said it will become clear over the next few weeks whether we are heading into another big peak.
"We are seeing this continuing, long plateau of cases but with a slight rise. We need to wait a few weeks to see if this is really going to be a major wave or not."
Baker said there are Omicron variants coming from overseas that will be better at "escaping our immunity" and therefore could cause a COVID-19 wave.
"They have an advantage over the ones they are replacing. And that means that they will be better at escaping our immunity, whether that immunity is from previous infection or from vaccine.
"That is just natural selection in operation but it does have a consequence for us because it means these new variants will come through, they will be more infectious, effectively, they will infect more people, more people getting this infection every day, more people going to hospital, and eventually more people dying as well."
Baker said this was especially causing concern because the hospitals are already overwhelmed by a combination of COVID-19, a bad winter illness season and critical staffing shortages.
He said the best way to deal with new variants is to minimise transmission wherever possible.
"I think the main thing is to dampen down transmission of these viruses, and that means wearing masks in high-risk indoor environments and I think particularly schools.
"I think to get through winter, we need to reintroduce a mask mandate for our schools. Obviously, everyone should be getting their flu vaccine and COVID boosters. Now, that's really important.
"It's also still very important to stay away from school or work if you have symptoms, even if you don't test positive for COVID-19, you may have influenza virus or another virus. So I think it's very important to still have that seven days away from work and school if you've got respiratory symptoms."
