More than half of the vaccine-eligible Covid-19 cases in the Lakes District Health Board over the past two months were not vaccinated.
And all four of those people admitted to hospital with the virus were unvaccinated, data provided by Toi Te Ora Public Health revealed.
There were 126 confirmed community cases between November 12 and January 17 in the district, of whom 27 were children under the age of 12.
Of the remaining 99 cases, 56 were unvaccinated, 15 had received their first vaccine dose and 28 were fully vaccinated.
An infectious diseases expert says the numbers were consistent with data from overseas — that the second dose was "very, very effective" at preventing illness from Covid-19.
It comes as there were five new cases in the Lakes District Health Board yesterday, all in the Rotorua area.
Four of the cases were linked to previously reported cases, meanwhile, the other is being investigated to determine any links. All cases were isolating at home or in managed isolation.
According to the Ministry of Health as of 11.59pm on Tuesday, the health board was 564 jabs away from reaching the 90 per cent fully vaccinated target.
Toi Te Ora Medical Officer of Health and incident controller Dr Phil Shoemack said "now is the time" to get vaccinated.
"Vaccination is the best way to keep yourself, your loved ones and the community safe from Covid-19.
"For people aged 18 years and older, a booster shot is available, providing better protection against the Omicron variant than the two-dose course.
"Booster shots can be received four months after a second shot."
There were 15,607 residents of the Lakes health board who were eligible for their booster shot as of January 5. Of those, 12,525 or about 80 per cent had already received the third shot.
Unichem Central Mall pharmacist Pavorn Patanasiri said demand for the booster was high.
"It's been absolutely mental," Patanasiri told the Rotorua Daily Post. "It's just constant from our perspective."
Patanasiri said about two-thirds of those lining up for vaccinations over the past few weeks were getting their booster.
The Pfizer vaccine was made available to children aged 5 to 11 from January 17.
More than 120,000 doses of the child vaccine were delivered to about 500 vaccination sites around New Zealand.
In Rotorua children's vaccinations are available at Ranolf Medical Centre, the Rotorua Covid-19 Immunisation Hub at Central Mall, Unichem Central Pharmacy, Te Runganga o Ngati Pikiao and Owhata Pharmacy.
Unichem Central Mall Pharmacy is not yet providing vaccinations for children aged 5 to 11 but was going through the approval process to do so.
Patanasiri said special equipment and training were needed for approval to administer the paediatric vaccine.
University of Auckland infectious diseases associate professor Mark Thomas said the health board's numbers were consistent with data from overseas.
"Essentially, we know from studies and this data fits with it, in the months after your second dose the vaccine is very, very effective at preventing you from becoming unwell with Covid.
"The fact that more people in the younger age group have become sick [reflects] how they perhaps felt not so concerned about becoming sick and so did not get vaccinated."
Thomas said while New Zealand seemed to have dodged the Omicron bullet so far, experience showed an outbreak of the new strain would come.
"It is extremely likely that Omicron will spread in the community. It may not be for a few months; it may be before."
Thomas said Omicron was more easily passed from person to person than other strains.
"It will cause severe illness in some people and for each of those people that's potentially a terrible tragedy."
Thomas said it is possible that Omicron will be followed by a strain that is more easily spread and also more serious.
"There are two different ways to becoming relatively immune to Covid, by being vaccinated or by contracting the disease."
The figures come as the country braces for Omicron after MIQ reported a tenfold increase in positive Covid-19 cases at the border compared to December.
The Government has said the MIQ system is facing "extreme pressure" from Omicron-infected arrivals and on Tuesday it was announced the latest MIQ room release was postponed due to the "unprecedented number of Omicron cases".
Meanwhile, an announcement is expected today after Cabinet met yesterday to consider the latest about Covid-19 and review the traffic-light system.