It is not always understood that cervical cancer is usually caused by a sexually transmitted infection (STI). More than 70 per cent of cases are triggered by the human papillomavirus (HPV), a pathogen passed on during sex.

Last October, Gardasil, a vaccine against the four most damaging strains of HPV, was licensed. It will transform the prevention of the disease, which still kills 1,100 women a year in Britain despite a national screening programme. New research this week showed that vaccinating 70 per cent of girls would ultimately halve the incidence of cervical cancer. Further benefits are possible given a more expansive programme.

Gardasil sounds like the sort of medical advance to which it is impossible to object. But it has inspired surprising opposition, and not just from the irrational anti-vaccine lobby, which regards all immunisation with grave scepticism. As HPV is sexually transmitted, the vaccine needs to be given to girls before they become sexually active to confer maximum protection. This has alarmed some religious groups, which argue that vaccinating at an early age will encourage teenage sex.

This objection is entirely specious. The HPV vaccine will protect against neither pregnancy nor STIs such as chlamydia or HIV, which will always be a more immediate concern. It is hard to imagine any 13-year-old deciding to have sex purely because she has been immunised against cancer. This is a campaign inspired by those who regard abstinence as the only acceptable answer to STIs and teenage pregnancy.

At least parents do not seem to be buying it: a poll for Cancer Research UK has found that 75 per cent of mothers want the vaccine for their daughters, with only 12 per cent worried that it might make them more likely to have sex.

Yet, while the US, Australia and several European countries have wasted no time in including Gardasil in national immunisation plans, the Government committee that will consider the issue here will not even meet until next month. Even if it recommends it to ministers, it is touch and go whether vaccinations could possibly begin during the next school year.

Such a delay would expose thousands of girls to unnecessary risk. While the smear test programme has done much to prevent death from cervical cancer — it is estimated to save 4,500 lives a year — there are signs that it is becoming a victim of its own success. As the disease has become less visible, some women are becoming more complacent about it. New figures released on Monday showed that take-up rates among women aged 25 to 29 — the most vulnerable group — have fallen from nearly 80 per cent in 1995 to 69 per cent last year. Vaccination will not replace the need for screening, but it will ensure that fewer women slip through the safety net.

So, too, would another potentially controversial measure: giving the vaccine to boys as well as to girls. While cervical cancer does not affect men, HPV does, and they can pass it on to infect their partners. Immunising both sexes would eliminate 91 per cent of HPV cancers, compared with 78 per cent for girls alone. The logic is the same as vaccinating boys against rubella, which causes birth defects if contracted during pregnancy. It reduces the pool of individuals in whom the virus might be circulating, protecting women who cannot be vaccinated.

Adding boys to the programme would make it much more expensive. The cost per year of life saved would be £23,000, against £2,400 if only girls were covered. Even the higher figure, however, is well below the NHS cost-effectiveness threshold of £30,000. If there is room for sensible debate about Gardasil, this is where it lies. The only question that the NHS should be asking about this vaccine is not whether it should provide it, but how.

Mark Henderson is the Science Editor of The Times