The average age of those hospitalised was 54.
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New community cases were reported in Northland, Auckland, Waikato, the Lakes District, Bay of Plenty, Tairāwhiti, Hawke's Bay and Wellington, the ministry said.
Of the 91 new community cases, 65 were in Auckland.
There were also 39 new cases in managed isolation and quarantine (MIQ), with travellers coming from the United States, Australia, Britain, India, Pakistan, Canada and the United Arab Emirates (UAE).
The latest numbers bring the seven-day rolling average of community cases to 69, and the total number of active cases to 771.
Charlotte Bellis case shines light on MIQ system
Grounded Kiwis spokeswoman Alexandra Birt said today that the plight of pregnant Kiwi journalist Charlotte Bellis being unable to secure a spot in MIQ had shone a light on the situation in New Zealand.
"We know that this is not a new story ... this is what thousands of Kiwis across the globe are facing," she told Newstalk ZB's Mike Hosking.
Bellis' story had reached various parts of the world and more people, as a result, had started to realise how strict New Zealand's border restrictions are.
Surge in Omicron cases expected this week
Te Pūnaha Matatini modeller Dr Dion O'Neale said this week was likely to see an upwards shift in case numbers.
"Almost every other place in the world that's had an Omicron outbreak's seen a doubling time of around three days. We'd expect New Zealand to be similar."
Daily cases could jump to 200 by the middle of the week then double to 400 by the weekend.
"So that means about 100 cases a day at the start of the week, around the middle of the week we're probably looking at around 200 cases a day, and then doubling to around 400-ish by the end of the week.
"Maybe things will go badly - that will arrive on the Thursday or Friday, maybe things will go well and we'll make it to Sunday before we get to that level - it's that rough pattern of taking around three days to double."
O'Neale told RNZ that even though not all current cases were being confirmed as the Omicron variant, modellers expected it would be the majority soon and were now making their calculations based on its behaviour.
"Omicron cases grow faster than Delta and other variants, so we expect it to out-peak other variants and take over... it's safest for us to be assuming that a case that comes up is Omicron unless we know otherwise."
He warned Omicron had a very fast incubation period, or latent period - the time between a person getting infected and the point they showed symptoms and became infectious themselves.
Once a person realised they were sick, took action to get tested and their results were reported, it could be four or five days from the point of infection.
"That's important to remember: the case numbers we're seeing at the moment, those are infections that are already baked in, that happened some time ago."
This also means that patterns showing comparatively fewer people getting tested for Covid-19 in weekends or on public holidays skew the numbers: "That will affect how those case numbers grow in the short term," he said.
Booster update
The ministry said 13,376 booster doses were administered on Sunday taking the total to 1,300,364.
Those eligible were encouraged to get their boosters as soon as they were due.
"Boosters lower your chances of getting very sick and being hospitalised. Being boosted also helps slow the spread of the virus," the ministry said.
About 95 per cent of those aged over 12 in New Zealand have received one vaccine dose, with 93 per cent of over 12s having at least two doses.
About one in three Kiwi children aged 5-11 had now received their first jab.
Anyone who lives in Porirua and Wellington's northern suburbs is urged to get a test if they feel unwell with Covid symptoms after a recent positive result in Porirua.
Several new locations of interest were released yesterday, including an Auckland clothing store, a Christchurch hotel, several regional airports, a Gisborne McDonald's and several food outlets at Auckland Airport domestic terminal.
But as of 7pm last night, no new locations of interest had been classed as high risk, with anyone at the locations at identified times told to self-monitor for symptoms for 10 days.
Border reopening plea
Yesterday Tourism Industry Aotearoa (TIA) urged the Government to update its plans for reopening New Zealand's borders because Omicron had changed the game.
"The previous plan was developed to respond to Delta, not Omicron. If Omicron becomes endemic in New Zealand, there will be no health reason to keep our borders closed or to continue self-isolation or MIQ for international arrivals," said TIA spokeswoman Ann-Marie Johnson.
She said New Zealand needed to reconnect with the world, and that people were desperate to reunite with family and friends.
Prime Minister Jacinda Ardern said last week that Cabinet would be considering changes to the current border settings in the coming weeks, after the phased reopening announced in November was put on hold when Omicron emerged.
"We know that both New Zealanders and tourism operators will face tough times in the next few months so the time for planning for the recovery is now," Johnson said.
"We need a clear Omicron border opening plan. We believe that enough is known about how the pandemic will play out to justify serious work to develop the plan. On behalf of the industry, TIA is keen to work with the Government to support this."
Covid-19 Response Minister Chris Hipkins said yesterday that changes at the border would be announced "soon".
Meanwhile the Prime Minister tested negative for Covid-19 yesterday after being identified as a close contact of an infected flight attendant.
"The Prime Minister has returned a negative Covid-19 test," a spokesperson said.
"In line with Ministry of Health guidance she is required to continue isolating until the end of Tuesday, February 1, or as otherwise advised by Public Health."
Ardern is due chair today's Cabinet meeting remotely.
As the Prime Minister is not able to be in the Beehive in person, Deputy Prime Minister Grant Robertson will attend today's post-Cabinet media briefing on her behalf.
- Additional reporting, RNZ
