There are 237 people in hospital, with an average age of 52.
They are at Northland, North Shore, Middlemore, Auckland, Tauranga, Hawke's Bay, Capital and Coast, Hutt Valley, Canterbury and Southern hospitals.
Three people are in intensive care.
Of the 12,011 new community cases, 3807 were detected via PCR tests and 8223 were identified using RATs. In Auckland alone, 7702 cases were reported today.
Today's new case numbers are a 95.7 per cent increase over yesterday.
New Zealand's positivity rate - the percentage of tests that are positive - is now 27.4 per cent.
Yesterday, the country's reported positivity rate (via PCR tests) for the previous 24 hours was 10.9 per cent.
The locations of Covid-19 cases detected via PCR tests are: Northland (46), Auckland (1,565), Waikato (388), Bay of Plenty (279), Lakes (23), Hawke's Bay (54), MidCentral (112), Whanganui (13), Taranaki (37), Tairāwhiti (34), Wairarapa (10), Capital and Coast (182), Hutt Valley (85), Nelson Marlborough (79), Canterbury (355), South Canterbury (13), Southern (524) and the West Coast (6).
The location of one PCR result is unknown.
The locations of cases found using RATs are: Northland (87), Auckland (6,403), Waikato (544), Bay of Plenty (338), Lakes (140), Hawke's Bay (40), MidCentral (41), Whanganui (5), Taranaki (11), Tairāwhiti (18), Wairarapa (4), Capital and Coast (77), Hutt Valley (20), Nelson Marlborough (23), Canterbury (114), South Canterbury (5), Southern (343) and the West Coast (3).
The location of seven cases identified via RATs is not yet known.
There were 19 cases detected at the border.
There are now 39,413 active Covid-19 community cases in New Zealand.
There were 25,461 booster doses administered yesterday. About 68.8 per cent of the eligible population has been boosted.
Today's increase in Covid-19 cases - up 5874 on yesterday - was not unexpected, the ministry said.
"These case numbers and hospitalisations are another reminder that vaccination is our best defence against the virus.
"The further increase in cases today is not unexpected given the ongoing spread of Omicron and wider testing achieved from the combined use of rapid antigen tests (RATs) and PCR."
The ministry usually provides the vaccination status of those in hospitals in Auckland and Northland, but this information has been delayed today because of a technical issue.
In the past 24 hours, 30,979 PCR tests were processed.
The seven-day rolling average for PCR testing is 28,795.
There are 6.9 million rapid antigen tests in the country, the ministry says.
The ministry said phase 3 was "a more devolved model" to ensure health resources are focused on those who need it most.
New Zealand moved to phase 3 of the Omicron response at midnight last night.
It was very important to the overall response that people self-report positive results for RATs through My Covid Record so heath officials could understand the size of the outbreak, the ministry said in a statement.
"We'd like to thank the thousands of people who have been tested and already self-reported positive RAT results."
The ministry was expected to see the high demand for Covid-19 testing across the motu continue.
While there are still significant global supply constraints, the ministry said enough RATs had been secured to help New Zealand through a widespread Omicron outbreak in the coming months.
"Over the past two days, 5.2 million RATs arrived in the country. Another 10 million will arrive over the weekend, bringing our total supply to more than 22 million by Monday."
Tests were being shipped to community testing centres, GPs and pharmacies across New Zealand.
Critical services and businesses who needed them as part of the Close Contact Exemption Scheme could also access them.
People who used a RAT would get their result within 20 minutes, which would help identify cases sooner, reduce testing wait times, minimise disruption to business and ensure critical services and infrastructure workforce could continue operating.
There were also 523 first doses, 1101 second doses, 179 third primary doses, 1657 paediatric first doses and 178 paediatric second doses administered in New Zealand yesterday.
Across all ethnicities, and including people who were vaccinated outside of New Zealand, 96.5 per cent of those eligible and aged 12 and older have had one dose and 95 per cent have had two.
For eligible Māori aged 12 and older, 90.8 per cent have had one dose, 87.1 per cent have received two doses and 57.9 per cent of those due for their booster have had it.
For Pacific peoples (eligible and aged 12+), 97.8 per cent have had their first dose, 95.6 per cent have been double dosed and 55.6 per cent have been booted.
Across all ethnicities, 49.1 per cent of children aged 5-11 have had their first dose of the Covid-19 vaccine and 0.5 per cent have had two.
For Pacific children, aged 5-11, 40.9 per cent have had one dose and 0.7 per cent have received two.
There was growing evidence that three doses of Pfizer was protective against Omicron and the ministry strongly encouraged those due for their booster to get it.
Meanwhile, anyone with cold or flu symptoms that could be Covid-19 should get tested and isolate at home until they get a negative result and are feeling well.
"Regardless of your test result, it is still important that anyone who is unwell stays home to reduce the spread of other viruses."
The most common early symptom of Omicron was a cough followed by a sore throat and/or runny nose.
If people needed advice on managing your symptoms, or whether you should seek care, Healthline was their first port of call (0800 358 5453).
Vaccination rates of eligible people - including booster doses - for New Zealand's DHBs are:
• Northland DHB: first dose (90.3 per cent); second dose (87.8 per cent); boosted (67.9 per cent).
• Auckland Metro DHB: first dose (97.3 per cent); second dose (96.1 per cent); boosted (65.6 per cent).
• Waikato DHB: first dose (95.3 per cent); second dose (93.4 per cent); boosted (65.3 per cent).
• Bay of Plenty DHB: first dose (95.3 per cent); second dose (93.2 per cent); boosted (66 per cent).
• Lakes DHB: first dose (93.6 per cent); second dose (91.3 per cent); boosted (66.7 per cent) .
• MidCentral DHB: first dose (96.8 per cent); second dose (95.1 per cent); boosted (71.4 per cent).
• Tairāwhiti DHB: first dose (93.3 per cent); second dose (90.6 per cent); boosted (67.4 per cent).
• Whanganui DHB: first dose (92.4 per cent); second dose (90.4 per cent); boosted (72.3 per cent).
• Hawke's Bay DHB: first dose (97.2 per cent); second dose (95.1 per cent); boosted (69.9 per cent).
• Taranaki DHB: first dose (94.8 per cent); second dose (93 per cent); boosted (66.1 per cent).
• Wairarapa DHB: first dose (96.7 per cent); second dose (95 per cent); boosted (73.6 per cent).
• Capital & Coast DHB: first dose (98.7 per cent); second dose (97.8 per cent); boosted (76.4 per cent).
• Hutt Valley DHB: first dose (96.9 per cent); second dose (95.6 per cent); boosted (73.2 per cent).
• Nelson Marlborough DHB: first dose (96.8 per cent); second dose (95.3 per cent); boosted (75.2 per cent).
• West Coast DHB: first dose (93 per cent); second dose (91.1 per cent); boosted (72.5 per cent).
• Canterbury DHB: first dose (99.8 per cent); second dose (98.6 per cent); boosted (70.6 per cent).
• South Canterbury DHB: first dose (95.4 per cent); second dose (94.1 per cent); boosted (73.6 per cent).
• Southern DHB: first dose (97.8 per cent); second dose (96.5 per cent); boosted (73.5 per cent).
Yesterday, there were 6137 new cases in the community - almost double Wednesday's 3297 cases.
Just eight Covid-19 cases were detected at the border while 205 people were in hospital fighting the virus. Two were in ICU or HDU.
Earlier today, Covid-19 Response Minister Chris Hipkins announced changes for schools.
All school students would now be able to participate in school activities despite if they were vaccinated or not and gathering limits would no longer apply when unvaccinated students were participating.
A total of 40 million faces masks, portable air filters and CO2 monitors are being distributed and schools will have access to 700,000 rapid antigen tests if they need them.
The announcement comes as Covid is now in one in five schools. Hipkins said a week ago it was in one in 10 schools.
Under phase 3, only confirmed cases and household contacts of a confirmed case will need to isolate for 10 days.
A disparity between the new isolation rules and the border rules announced earlier this month has been flagged by director general of health Ashley Bloomfield.
Despite isolation requirements changing, people travelling under the new border rules from February 27 would get to skip MIQ but would still need to self-isolate.
Bloomfield has advised the Government of the matter.
A PCR test will also no longer be required to verify a positive RAT result - and RATs will be available across the country from testing sites, GPs, pharmacies and within workplaces. People will be able to self-report their positive results and notify contacts.
RATs will be free to those who require them for testing, and available for purchase for about $8 to $10.
Bloomfield said the PCR tests have served the country well and helped us understand the situation, but it was now at the stage where rapid antigen tests are the better option - given the high number of Covid cases in the community.
Meanwhile, calculation error on the part of the Government means vaccine mandates cover a quarter fewer people than initially believed.
It means the percentage of people covered by a Government mandate is just 30 per cent, not 40 per cent like the Government initially said.
This comes as the anti-mandate protest on Parliament grounds enters day 18.
While activity is quiet this morning, children were caught up in moves over territory yesterday as police manoeuvred more concrete blocks into place.
As riot police moved from Lambton Quay to a Bunny St blockade, several officers barged into camping areas and pulled some children out, along with adults caring for them.
The children were then stuck between riot police and a second line of police, until they were let through and able to cross the road towards the railway station.
