Key Points:

A controversal anti-cancer vaccine to be given to 300,000 teenage girls starts this week amid criticism the project is a public experiment.

The national human papillomavirus (HPV) immunisation programme will from tomorrow offer free vaccines of Gardasil to protect against the two major strains of the virus that cause cervical cancer.

The Government has pledged $177 million to the five-year programme to give girls aged 12 to 18 three injections to combat HPV, which causes 70 per cent of cervical cancer.

The disease kills about 65 women annually as another 180 are diagnosed.

Critics, including the researcher who helped develop Gardasil, have raised concerns about the safety and effectiveness of the vaccine, while wondering if it will encourage more young girls to be sexually active.

Medical professionals who are widely supportive of the plan include Dr Min Lo, the director of Auckland Sexual Health Clinic, who said Gardasil would help protect sexually active women, of whom nearly three-quarters were exposed to the skin virus HPV, which can lead to genital warts and vaginal cancer.

"Genital warts are very difficult to treat and can be a large cost to the health sector as well," said Lo.

"If this becomes an established vaccine then it will have a huge impact in the future."

Reducing the 30,000 abnormal smear tests caused by HPV would save money.

The tests needed medical follow-up and were a "burden" on the health system, said Lo.

But Auckland Women's Health Council spokeswoman, Lynda Williams, was concerned that adequate information was not available for parents, children and doctors.

Trials of Gardasil centred on 16- to 24-year-olds, as opposed to the younger age group targeted in New Zealand, said Williams.

Diane Harper, a researcher who helped develop the vaccine at New Hampshire's Dartmouth Medical School, said giving the vaccine to girls as young as 11 was "a great big public health experiment".

The vaccination is administered in the United States and Australia despite reports of fainting, paralysis and the death of a 19-year-old a fortnight after vaccination.

The Ministry of Health said there were comparable side effects to other common vaccines when the drug was tested on more than 27,000 women from 33 countries. Other global regulatory agencies have also found no evidence to link Gardasil to any deaths.

Williams said there were too many unanswered questions for parents to be confident of the drug's effectiveness.

"This is a political decision," she said. "So many decisions on women's health issues have been made in the lead-up to an election and been rushed. If you're going to spend hundreds of millions of dollars on a vaccine, there have to be more of these questions answered."

Family First director Bob McCoskrie said more questions needed answers.

"It seems we rushed in very quickly and committed a huge amount of money," he said.

"We can't find the money for Herceptin, which you could argue may have as many question marks over the effectiveness of it, but we can pour this money into Gardasil."

Increasing promiscuity among young girls was another possible problem, but it was more important for parents to not be pressured into having their children vaccinated, said McCoskrie. "We all want a cure to it but we've also got to be realistic about what works best."