Prime Minister Jacinda Ardern is urging parents to "listen to our experts" and get their children vaccinated against COVID-19.
A paediatric version of the Pfizer vaccine was made available to kids aged 5-11 on Monday, meaning about 476,000 children are now eligible to be immunised against the virus.
Queues were observed at some of the 500 distribution centres where the paediatric vaccine was available. Protesters attended several sites, shouting into megaphones and handing out pamphlets with warnings widely dismissed by the scientific community.
Glenn Mulholland, an anesthesiologist, tweeted: "Watch out for anti-vaxxers at the Glenfield vax centre - walking down line of cars scaremongering with leaflets about contents of vaccine."
"I think allegedly is the word that we would use," Ardern told reporters on Monday, in response to the warnings spread by the COVID-19 vaccine sceptics.
"My overall message is the same as it has always been: I still absolutely believe that we are all motivated by the same thing and it's that we want to look after one another," Ardern said.
"We know from the evidence, from the data, from our scientists and from our experts that the best way to look after one another is to be vaccinated, and that means receiving a booster.
"To families: we listen to our experts, and they've advised us that the best thing we can do to look after children and their families is for them to also receive the vaccine.
"I would just implore people, it's not about the Government here. It's about what the best advice possible is telling us. We're sharing that advice and if people have questions, please don't hesitate to reach out to those medical professionals you trust."
There has been disappointment expressed about the protesters.
"Imagine standing outside a vaccination centre holding signs saying 'freedom of choice', 'Govt is creating fear' while yelling at kids & tapping on car windows," Auckland Councillor Richard Hills wrote on Twitter.
"Parents & kids are there by choice & you're the only ones creating fear. What kind of person goes out to yell at kids!?"
Ardern shared a similar sentiment.
"Of course, my preference would be that no one would have any barrier or obstruction to them accessing what is ultimately medical support. The police, ultimately, are the ones that help ensure that places are safe."
A police spokesperson said officers were "monitoring the situation".
Starship paediatric consultant Dr Jin Russell has been involved in providing independent expert advice on protecting children from COVID-19 to the Ministry of Health.
"We now have real-world safety data from over 8 million doses of the Pfizer vaccine administered to children aged 5-11 years in the United States. I have confidence the Pfizer vaccine is very safe for children," she said on Monday.
"The best thing a parent can do to prepare their children to be immunised is to talk to them about what is going to happen. Tell them there will be a small needle and that they will feel a sharp scratch or sting briefly but then it will be over."
Dr Russell acknowledged that children "may have a sore arm, fever, headache or feel tired" after receiving the vaccine.
"A key thing is to tell them why they are going to be vaccinated. I say to my boys, 'you are going to be vaccinated to protect yourself against COVID-19, and to protect our family, your grandparents, our community, and other kids at school who may be more at risk from COVID-19 if they catch it'."
Auckland's COVID-19 vaccination programme clinical director Dr Anthony Jordan said children may have milder symptoms, some will still get very sick and end up in hospital if they do get COVID-19.
"If parents are due for their boosters, they can get them done at the same time to help provide reassurance."
More than 3200 children had turned out to vaccination centres, GPs and pharmacies, as of 1pm, according to the Northern Region Health Coordination Centre.
Tamariki need two doses of the vaccine to be fully protected. The two doses are to be given at least eight weeks apart.
Kids in New Zealand get free vaccinations against 12 diseases, including whooping cough, measles and polio.
