Within a month of easing restrictions, cases began to soar, reaching a daily high of around 5300 in late October.
Yesterday, the country, which has run one of the most successful and sophisticated epidemic control programmes in the world, reported more than 2000 new infections and eight deaths.
Baker said there were some key differences with New Zealand's profile and experience.
Singapore's vaccination roll-out began much earlier – it's now administering booster shots – and its population of 5.6 million was concentrated in an area less than that of Auckland.
But there were still lessons that applied here.
While 86 per cent of its total population was now fully vaccinated, compared to 66 per cent in New Zealand, Singapore also had disparities in its coverage – particularly among older people who hadn't received both jabs.
Like New Zealand, Singapore has minimal natural immunity to Covid-19 because it also ran a successful elimination strategy during the first 18 months of the pandemic, saving many lives in the process.
Health experts have been warning New Zealand still has large rural pockets with low vaccine coverage and poor access to clinics – and that vaccination rates among eligible Māori, at just 61 per cent for first dose and 77 per cent for both, desperately need to come up.
But a nationwide move to the traffic light system could occur within weeks, with Prime Minister Jacinda Ardern already having signalled the regime could be put in place before every DHB reaches a 90 per cent threshold.
The Herald understands the system, soon to be introduced in Auckland, could be extended to the rest of the country by mid-next month, with Auckland's boundary restrictions to ease soon afterwards.
Baker worried that allowing the virus into communities too early could cause thousands of avoidable infections and deaths.
"Basically, once you have widespread exposure, all of those small gaps in the protection provided by the vaccine become really important and all start to add up."
Baker pointed to what's traditionally been our deadliest infectious disease – and which is expected to compound our Covid-19 headache when it re-seeds in the country – influenza.
"It's a pretty grim yardstick to use, but it's responsible for about two per cent of deaths every year in New Zealand. In a very bad year, it may cause an average of about two deaths a day," he said.
"Covid-19 may be more like 10 deaths a day and that could quickly add up to maybe 3000 deaths or more over a year, which would push it into being responsible for 10 per cent of all deaths in New Zealand.
"While these are very rough orders of magnitude, we are seeing this sort of mortality in the UK."
If the UK's mortality rates were translated to a New Zealand setting, he said, daily deaths would be in the order of 10 to 15.
Not only did the UK have a similar level of vaccine coverage, with 67 per cent fully vaccinated, its population also had a large degree of natural immunity from exposure to the virus.
"So, if you add that up, in a way, they are somewhat like Singapore – and it can tell us a lot about what this virus could look like as an endemic threat to New Zealand," he said.
"That's why, before it gets really widespread here, I'd like to see us get immunisation coverage much higher, particularly in Māori, and I'd like to see the roll-out extended to children."
Australian children aged between 5 and 11 will be able to get vaccinated from January, while vaccines are already being distributed among children in the US.
Our regulator, MedSafe, this month received an application for Pfizer to use its paediatric jab among New Zealand's more than 460,000 5-to-11-year-olds.
With that and the addition of boosters – soon to be available for people who received their first jab six months ago – Baker said New Zealand would be in a position to slow the virus' spread throughout the country.
"I'd support sticking with the Government's original timetable of really limiting spread of Covid-19 across New Zealand," he said.
"That means sustaining elimination outside Auckland for now. It will also mean we can have a chance to see how the traffic light system works in practice, after it's introduced in Auckland."
At the same time, Baker said the Government should bring forward plans to allow most arriving double-vaccinated travellers to go straight into home isolation.
That would free up MIQ space for infected people in the community, whose homes weren't suitable for home isolation in Auckland.
"The number of active cases self-isolating at the moment – more than 2000 at present – is a much bigger risk to Aucklanders than the tiny number of infected people in MIQ hotels."
