Jacinda Ardern says she hasn't seen any research to suggest people who take the COVID-19 vaccine will face a similar mishap as a character from Willy Wonka and the Chocolate Factory.
The Prime Minister spoke to her Instagram followers in a Live video from the floor of her home on Sunday night about the COVID-19 vaccine rollout.
A small group of New Zealand's vaccinators were the first to get the jab on Friday, before the wider roll-out began on Saturday to vaccinate the country's border workers.
The public is expected to be offered the vaccine in the coming months.
While taking viewers questions, Ardern noted one asking: "What percentage of people will blow up and turn purple like Violet from Willy Wonka?"
Violet, a character in the well-known Roald Dahl book, is known for chewing a gum that is not ready for human consumption which causes her to turn blue/purple and expand into the shape of a human-sized blueberry.
"Great question," Ardern replied. "I haven't seen any particular research written about the percentage of people who will blow up and turn purple like Violet from Willy Wonka so I can only assume that that is not a documented side-effect - which is good news for all of us."
She said she assumed it was a joke question but: "I appreciated it anyway".
There have been some concerns about the safety of the COVID-19 vaccination, with nearly a quarter of Kiwis saying they are unlikely to get it in a recent survey.
But experts have assured the public that the vaccine is safe.
"This vaccine has gone through rigorous safety, immunogenicity, and efficacy testing," Otago University Department of Microbiology and Immunology associate professor James Ussher said.
"Tens of thousands of people around the world have volunteered to participate in the clinical trials and we owe them our gratitude. Furthermore, this vaccine has now been delivered to millions of people around the world, and its safety confirmed. The public should have every confidence in the vaccine development process for this vaccine; the rigour of that process has been confirmed by a robust assessment by Medsafe."
Loretta Roberts, national manager of the Immunisation Advisory Centre (IMAC), agreed the vaccine is safe.
"It has a very good safety profile. I think about 180 million doses of COVID-19 vaccines have been given. When vaccines are made there is very, very careful manufacturing requirements and again in New Zealand, we have Medsafe, which has done a robust check on all of the things that are required for the safety of the vaccine. So I think we can be very confident we have a vaccine with a good safety profile."
During the Instagram Live, Ardern said it's important people get vaccinated.
"We've never had a vaccine program this large in New Zealand, but we have never experienced a pandemic like this before ever," she said.
"I know people have lots of questions, the best thing I can say to you is that we wouldn't be asking this of you if we didn't believe it was going to keep you and your whanau safe and well."
Ardern told The AM Show on Monday she is "torn" over when she will get the COVID-19 vaccine as she wants to protect border workers first - but also wants to send a message the vaccine is safe.
"We need to reach into those communities where they might be a bit hesitant and give them that reassurance."