The HPV vaccination could have the unintended consequence that more women with cervical cancer will not be diagnosed, the Ministry of Health has warned.

The ministry's national screen unit is concerned that young women believe they are protected from the disease once they are immunised.

But the vaccine does not protect against 30 per cent of HPV types that can lead to cervical cancer.

The ministry says there is a risk that these women will not attend regular screenings once they reach the recommended age of 20.

"It is essential that women fully understand the need for regular screenings to protect themselves from cervical cancer, whether they have been immunised or not," the National Screen Unit said.

"This could undo the steady increase in screening rates the [unit] has achieved through successful media campaigns, health promotions and active efforts of providers to inform women of the necessary screenings."

An average of 66 New Zealand women die from cervical cancer each year, says Family Planning NZ.

The human papillomavirus is the main cause of the disease and four out of five people become infected with this STD at some time in their lives, with the peak incidence of infection between the ages of 16 and 20.

The ministry recommends that all women aged 20 to 70 should have regular three-yearly smear tests if they have ever been sexually active.

Government funding for the vaccination was introduced in schools early last year and the unit will continue its review of the effects of the HPV vaccination on cervical screening.

A screen unit official said the unit would make changes to the programme to "ensure it maintains quality and cost-effectiveness".

Family Planning New Zealand recommends the vaccination and works with the ministry using pamphlets, website information and news releases to make women aware of the risk.

The chief executive of Family Planning, Jackie Edmonds, said face-to-face contact between clients and their nurses and doctors was the best way to remind people that even though they might have had the HPV vaccination, they still needed regular cervical smear tests.

Since the introduction of the national cervical screening programme communications campaign in late 2007, there has been an increase in screening rates of 6.7 per cent for all women, 13.8 per cent for Maori women and 25.5 per cent for Pacific women.

HPV Vaccine
* A consequence of the HPV vaccination could be that women will go undiagnosed for cervical cancer.

* There is concern that young women will not attend regular screenings once they reach the age of 20.

* The HPV vaccine does not protect against 30 per cent of HPV types that can lead to cervical cancer.