June 10, 2015

expert reaction to study looking at dosage of HPV vaccine and level of protection against HPV infection

A vaccine against the human papillomavirus (HPV) is offered to adolescent girls in the UK with the aim of protecting against cervical cancer, and the efficacy of the vaccine when using different numbers of doses is the subject of a study published in the journal Lancet Oncology. Two vaccine doses are currently given, with the research team reporting that in their study similar levels of protection were given by one, two or three doses of the vaccine.

Dr Vanessa Saliba, PHE Consultant Epidemiologist, said:

“The Human Papillomavirus (HPV) immunisation programme for adolescent girls was introduced in England in 2008 with the aim of reducing the incidence of cervical cancer in women. School-based HPV immunisation delivery has successfully achieved high coverage for the full three-dose course which has been consistently above 86% over the last three years.

“In March 2014, based on the latest immunological evidence, the Joint Committee on Vaccination and Immunisation (JCVI) advised a change from a three to a two-dose schedule in the routine programme, which was implemented in September 2014. The HPV vaccine used routinely in the national programme in England when it started was Cervarix, which protects against HPV types 16 and 18, which are responsible for over 70% of all cervical cancers in Europe. This was changed to Gardasil in September 2012, which in addition protects against a further two strains of HPV – types 6 and 11 – that cause the vast majority of genital warts.

“While The Lancet Oncology study is encouraging, we look forward to further research being conducted into HPV vaccine dosage to confirm these results. JCVI continues to keep the HPV immunisation programme under review and will consider this new evidence in due course.”

Prof. Margaret Stanley, Professor of Epithelial Biology and Director of Research of the Department of Pathology, University of Cambridge, said:

“The paper from Kreimer and colleagues reporting data from a post hoc analysis of two trials with the bivalent HPV vaccine Cervarix that suggests that even one dose of a VLP vaccine provides equivalent protection against infection with HPV 16 and 18, the most important of the cancer causing HPVs, could be the game changer for the implementation and uptake of these vaccines worldwide.  Delivering one dose rather than two or three would be easier in settings with little medical infrastructure and crucially cheaper, not just in vaccine costs but delivery costs.

“However there is still a way to go before one dose vaccination could even be considered for introduction.  As Kreimer and colleagues point out themselves, this is a post hoc analysis, the numbers are small and the measure of efficacy is not disease but infection and incident (detection of HPV DNA once) rather than persistent infection. Nonetheless the striking data in this study support the calls for clinical trials that assess the efficacy of one dose of HPV vaccine in women and men.  These are unlikely to be sponsored by the manufacturers of these products but because of the overwhelming public health importance of this question should be a priority for national and international funding agencies.”

Dr Mark Jit, Senior Lecturer in Vaccine Epidemiology, London School of Hygiene & Tropical Medicine, said:

“Many countries including the UK recently switched from giving three doses to giving two doses of the HPV vaccine to girls up to 14 years old. This followed findings from Costa Rica and other studies that two doses of vaccine may be enough to protect women from cervical cancer. The latest news that even one dose may be protective holds promise, although further studies are needed before we will be ready to consider a one dose schedule.”

‘Efficacy of fewer than three doses of an HPV-16/18 AS04-adjuvanted vaccine: combined analysis of data from the Costa Rica Vaccine and PATRICIA trials’ by Aimée R Kreimer et al. published in the Lancet Oncology on Wednesday 10 June 2015. 

Declared interests

Dr Vanessa Saliba doesn’t have any conflicts of interest to declare.

Prof. Margaret Stanley: “I have acted as consultant for GSK Biologicals, MSD and SPMSD, the manufacturers of the current vaccines.”

Dr Mark Jit also works at the Modelling and Economics Unit in Public Health England.