Over 90% of cases of cervical cancer are caused by exposure to human papillomavirus (HPV), a sexually-transmitted infection. While regular cervical screening tests have been effective at reducing cervical cancer incidence, many countries have solidified their prevention campaigns by introducing HPV vaccination programs. There are currently two licensed HPV vaccines on the market: Cervarix, made by Glaxosmithkline, and Gardasil, made by Merck & Co. Currently, Australia, Denmark and France use Gardasil, while the UK and the Netherlands use Cervarix. However, from 1^st September 2012, the UK government will overhaul the national HPV vaccination program, replacing Cervarix with Gardasil.

So why the change? Two human papillomaviruses carry the highest risk of cervical, anal, vaginal and penile cancers: HPV 16 and 18. Both vaccines are protective against these two viruses. Yet Gardasil protects against an additional two viruses, HPV 6 and 11, which are directly linked to the development of genital warts. So, broader protection from a greater number of sexually-transmitted viruses is achieved with Gardasil compared to Cervarix.

This leads to the obvious question: why didn’t the UK use Gardasil from the very beginning? It probably boils down to a short-term cost analysis made at a time when solid clinical evidence was lacking. The full course of 3 injections of Cervarix costs approximately £241.50, while Gardasil comes in at a slightly more expensive £265.50. But when you consider longer-term cost-benefit ramifications of using the bivalent Cervarix (which protects against two viruses) over the quadrivalent Gardasil (which protects against four viruses), Gardasil has the greater potential to reduce the healthcare burden of HPV infections (i.e. treatment costs) since it protects against more disease-causing HPV types.

Cost is also likely a major reason why the HPV vaccination program hasn’t been rolled out to include young men, despite the fact that HPV infection is a major cause of penile cancer. An additional consideration is that if uptake of the HPV vaccine in young women reaches high enough levels (>90%), and the vaccine-induced protection lasts for a long time, then vaccinating young men becomes partially redundant: herd immunity, at least in heterosexual couples, would have been achieved. This means that there would be no reservoir of female infection to be transmitted to men: men would be protected simply by women being vaccinated.

HPV vaccination, regular cervical screening tests (every 2-5 years), the use of prophylactic condoms during sexual intercourse and limiting your number of sexual partners can all help to minimise the risk of HPV infection. For more information, go to http://www.cdc.gov/std/hpv/stdfact-hpv.htm/