Health officials say Covid-19 case numbers appear to have plateaued but the 'complex mix' of variants could see daily cases hit 11,000 again over the summer.
Covid-19 cases in New Zealand have been rising and yesterday topped 4000 for the first time since August.
Epidemiologist professor Michael Baker told First Up those numbers indicated the country was experiencing its third Omicron wave.
Speaking at Middlemore Hospital today, Deputy Director-General of the Public Health Agency Dr Andrew Old said latest wastewater results supported the trend of stabilising Covid-19 cases that had been seen over the past two weeks.
However, he noted the number of people hospitalised with Covid-19 had increased slightly, with 339 people in hospital as of midnight on 13 November, up from 322 a week earlier.
It was "too early to say" whether the current plateau in cases would be sustained, and cases in the past two days had shown some signs of increasing again, he said.
"The outlook for summer, with more people travelling and with the unpredictable mix of variants circulating, at this point remains uncertain."
The mix of variants made it "more challenging" to predict what the future shape of the current outbreak may look like, he said, but health authorities were planning for a possible continued increase in cases and hospitalisations through to the end of the year.
Old said current modelling indicated cases could rise to a peak similar to that seen in July - between 10,000 and 11,000 cases per day.
Hospitalisations and deaths also could also peak at similar levels to what was seen in July.
Reinfection rates were also climbing, Old noted, saying they now accounted for about 20 percent of all reported cases.
He encouraged people to ensure they were up to date with their vaccinations, stay home if they were symptomatic, test if unwell and to open doors and windows as much as possible if they were entertaining over the summer months.
Old said there was also "good evidence that mask use reduces transmission".
The ministry would be publishing a "summer checklist" to help people prepare for the summer period, and people should think about how they would manage if they fell ill while on holiday, he said.
New Zealand remained in a "strong position" to manage the ongoing Covid-19 cases but Old cautioned: "We're not out of the Covid woods yet".
Second booster, immunity
Ministry of Health chief science advisor Dr Ian Town, who is also chair of the Covid-19 Vaccine Technical Advisory Group, said boosters remained an important tool in the country's response to the virus.
"These boosters certainly lift the antibody levels, which improves that vital protection against the virus."
With the number of cases circulating in the community, many people had been exposed to the newer variants, he said, which - in addition to boosters - would help with hybrid immunity.
Town said that from 18 November, Māori and Pasifika people aged 40 years and above will be eligible for a second Covid-19 booster. The age of eligibility remains 50 for everyone else.
The decision to lower the age of eligibility for those groups was "based on clear evidence from data that we've been able to gather here in New Zealand", he said.
That data showed the risk of death was for "around twice" for Māori and Pasifika people who contracted Covid-19, and that risk kicked in earlier - "around the age of 40".
"Our advice remains the same - get the vaccinations."
The government said earlier this month that it had no plans to launch an annual Covid-19 vaccination booster for the majority of people.
However Minister for Covid-19 Response Dr Ayesha Verrall said it was looking at multi-variant vaccination, which could be made available to the country's most vulnerable populations by 2023, if necessary.
'Significant challenges' remain
Te Whatu Ora interim national medical director Dr Pete Watson said Covid-19 continued to put pressure on the health system.
"The recent increase in Covid-19 case numbers is a reminder of the need to remain vigilant," he said.
"More than two years into the pandemic, global health systems are still facing significant challenges in providing essential health service."
New Zealand's health system was no exception, Watson said, noting the hospital occupancy remained high.
"The pressures placed upon our work health force have been unprecedented."
However, he said a number of steps were being taken to address workforce shortages.
"We are training more doctors and nurses, and we're supporting people who have stepped up to work in the Covid-19 vaccination programme to also enter the workforce."
Bringing first-year GP registrars' pay into line with that of hospital registrars, doubling the number of nurse practitioners being trained each year and making it easier for overseas nurses to work in New Zealand were among the other measures being undertaken.
"In coming months, we will likely continue to see a high prevalence of Covid-19, he said, "but we will get through."