Today, Dr Ashley Bloomfield said 42 people in New Zealand were hospitalised with Covid-19, and all those patients were in Auckland.
Bloomfield has said Auckland could be prioritised in the Covid-19 vaccination programme if extra supply cannot be delivered.
Apart from health experts, the idea has now won the support of a major national business group and top economist. A mayor just outside Auckland supports it too - though with one caveat.
At least six reasons explain why Auckland might need to be prioritised in the rest of the vaccine rollout.
1. International exposure
All Covid-19 outbreaks in New Zealand have originated from international airports, ports, or MIQ facilities.
Auckland has the country's busiest airport, the most MIQ hotels, and the busiest seaport.
The immediacy of the risk was amplified even today when it was revealed that a man with Covid-19 fled the Novotel & Ibis Ellerslie facility without permission at 1am.
2. Auckland is densely-populated and Aucklanders are highly mobile
Tens of thousands of Auckland homes are overcrowded. The 2018 Census found more than 200,000 people, or about one in seven, lived in crowded households.
"Definitely, the virus transmits in enclosed spaces among groups of people, workplaces and homes," microbiologist Dr Siouxsie Wiles said today.
"So if you've got big families living in cramped conditions, you will see more spread."
It's not just cramped homes or busy workplaces influencing the dynamics of how a pandemic spreads.
As the city's notorious traffic jams show, Aucklanders are mobile, frequently commuting a long way for school, work or shopping.
The Commuter Waka tool from Stats NZ showed a vast majority of people who worked or went to school in Penrose, Henderson, the CBD, Newmarket and the airport precinct lived elsewhere.
These areas alone have some of the country's biggest financial, retail and industrial centres, and include major workplaces where working from home is not possible.
Auckland is the country's biggest manufacturing centre and the pandemic has already struck factory workers, including a Sistema Plastics employee.
Sistema staff considered close contacts were told to self-isolate and get tested.
Factories were at significant risk from outbreaks and protecting factory workers and their families was important, Wiles said.
Wiles and vaccinologist Professor Helen Petousis-Harris both said mobility was a factor in determining how many people would be potentially exposed to an infected person.
3. Auckland is New Zealand's biggest urban economy
When Auckland shuts down, many producers across New Zealand lose out on the city's huge consumer market.
"Auckland is about one-third of the New Zealand economy," economist Cameron Bagrie said today. "The indirect effects on the broader New Zealand economy are going to be material."
It's just not Auckland's big population that matters to businesses across New Zealand. Bagrie said if you handle any imported goods, odds are the goods are coming through Auckland.
"Auckland is the primary gateway in New Zealand. That absolutely makes Auckland a flashpoint."
The Forest Owners Association told NZ Herald Business the latest level 4 lockdown had set back an already disrupted export supply chain by 12 to 18 months.
Business NZ chief executive Kirk Hope said his organisation supported a strong vaccine rollout for the whole country.
Hope said all of New Zealand faced major consequences when Auckland was subjected to Covid-19 lockdowns.
"Auckland's been here now at alert level 3 or above five times."
He added today: "We would recognise that there is a more acute need in Auckland because of these factors."
4. For Northland's sake
Ongoing outbreaks and the inevitable Auckland lockdowns also effectively slice the upper North Island in two, isolating Northland.
Kaipara District Mayor Dr Jake Smith supported vaccine priority for Auckland, but said Northland's roughly 200,000 people should be considered a priority too.
"Right beside Auckland, the less risk there is coming into Kaipara from Auckland, the better."
He said Northlanders keenly understood how vulnerable Auckland was due to its port and MIQ facilities.
For people in the North, all roads to the rest of New Zealand lead through Auckland.
"When Auckland goes into a high level of lockdown, Northland gets, by dint of geography, a whiplash effect."
Smith said many parts of Northland had significant Māori populations and some local communities were especially vulnerable to Covid-19.
He said Northland depended on Auckland more than other regions did, and for that reason thought should be given to prioritising Northland in vaccine rollouts too.
The Local Democracy Reporting service found Northland Māori Covid-19 vaccination rates were almost four times lower than those for Europeans.
Northland District Health Board chairman Harry Burkhardt last week told LDR that vaccination was a crucial part of iwi and hapū protecting themselves.
5. Vulnerable population groups
Auckland is the most multicultural city in New Zealand, and authorities have admitted more work was needed in articulating key health messages to some communities.
A study of more than 1500 New Zealand coronavirus cases, published in The Lancet, found severe outcomes were more strongly associated with Pacific peoples and Asian ethnicities relative to other ethnic groups.
The Pasifika community has borne the brunt of the latest outbreak, and was also disproportionately affected in last year's Mt Roskill church cluster.
Inequitable morbidity and mortality for Māori and Pacific peoples, seen during previous flu pandemics, continued for many diseases today, The Lancet study added.
"Auckland has got a portion of the population that you'd put in the more vulnerable categories," Bagrie said.
It's not just the overcrowding already mentioned.
Auckland has high concentrations of people born overseas who might have difficulty accessing support networks and official communications during lockdown.
Manurewa-Papakura councillor Daniel Newman raised concerns this week about low vaccination rates in some Auckland communities.
"The uptake of vaccination among Māori and Pacific peoples, particularly those in younger age groups, is still not high enough," Newman told the Herald.
Auckland has endured more lockdowns than any other town or city. Previous outbreaks have proliferated here and without vaccinations, future Covid-19 strains are likely to gain a toehold in Auckland before anywhere else.
Petousis-Harris said the new Delta strain outbreak was a realisation of concerns many experts had long ago about where the next outbreak would strike.
She said prioritising vaccinations for Auckland had always been in the works.
"It was always part of the master plan. Of course, it just turned out to be on a much larger scale than we might have foreseen all those months ago," Petousis-Harris said.
"It's important for the whole country that Auckland gets out of lockdown as fast as possible."
Bagrie said apart from the many reasons of national economic significance, there was a moral question involved.
He said the country should ask if prioritising Auckland for vaccinations was the right thing to do.
"The answer is: 'Hell yes.'"