This is despite the fact that Cervarix may provide better protection against cervical cancer. However, the authors stress that considerable uncertainty remains about the differential benefit of the two vaccines.
Human papillomavirus (HPV) is a common sexually transmitted infection seen most often in young women and adolescents. There are more than 100 types of HPV - some cause genital warts, but others cause cancers including cervical cancer.
Two HPV vaccines (Cervarix and Gardasil) are currently available. Both protect against HPV types 16 and 18, which cause over 70% of cervical cancer cases, as well as several other types of cancer. Gardasil also protects against types 6 and 11, which cause the majority of genital warts as well as a rare disease called respiratory papillomatosis.
In 2008, the UK government chose the bivalent vaccine Cervarix for its HPV vaccination programme, based partly on analyses by Mark Jit and his colleagues at the Health Protection Agency suggesting that Cervarix would have to be £15 to £23 cheaper per dose to be as cost-effective as Gardasil. However, the choice of vaccine will be re-evaluated when the current tender for the vaccination programme ends.
Since then, further evidence has emerged to differentiate the two vaccines. For instance, Cervarix appears to give better protection against cervical cancer caused by HPV types other than 16 and 18. Gardasil has now also shown protection against vulvar, vaginal and anal cancer.
Using this latest evidence within a mathematical model, Mark Jit and his team set out to re-evaluate the two vaccines to inform the next round of vaccine tendering.
They found the price differential between the two vaccines was larger than their 2008 analysis. Based on the most recent evidence, Cervarix would have to be £19 to £35 cheaper per dose to be as cost-effective as Gardasil, mainly due to a lack of protection against genital warts.
When all differences between the two vaccines are considered, "the quadrivalent vaccine (Gardasil) is still more cost effective if the two are equally priced," conclude the authors. However, they stress that "considerable uncertainty remains about the differential benefit of the two vaccines."
An accompanying editorial says that modelling can help decision makers, but ultimately the tender price is the final determinant of cost-effectiveness.
