The Cancer Society is urging parents to ensure their children get the HPV vaccine after vaccination rates plummeted during the Covid-19 pandemic.
About 45,000 tamariki had missed out on the HPV vaccine, which protects people from the human papillomavirus that can cause six types of cancer.
The vaccine is provided free to 11 and 12 year-olds at most schools, but Cancer Society Medical Director Dr Kate Gregory said lockdown disruptions had made low immunisation rates even worse.
Tamariki who missed out on the vaccine at school, or whose schools do not offer it, can still get it at their GP or medical centre - and it is vital they do, Gregory said.
"All tamariki - both boys and girls - should have the HPV vaccine to protect them from developing cancer in later life.
"There's really good evidence that it reduces the risk of people developing cervical cancers, and also other cancers in other parts of the body such as head and neck cancer.
"I treat patients with cervical cancer, and honestly, having a vaccination preventing this cancer is way better than going through the treatment for it."