A Single Dose of HPV Vaccine Could Be Enough to Prevent Cervical Cancer

Wednesday 10th June 2015

Researchers have called into question the need for numerous doses of the HPV vaccine after claiming a one-dose might be sufficient and ought to be investigated to protect most women against cervical cancer.

The suggestion has been brought up by researchers of an analysis published in The Lancet Oncology. The analysis combines results from two major phase three trials.

Dr Aimee Kreimer from the US National Cancer Institute is co-lead author. She said there are possible advantages, as if a single dose is enough, it could condense administration and vaccination costs whilst improving the uptake.

She also said this is particularly significant in lower income parts of the world, as this is where over 80 percent of cervical cancer incidences take place.

The findings are introduced with information regarding the burden of this type of cancer. Cervical cancer is one of the main causes of cancer deaths in females across the world, affecting women in less developed counties disproportionately.

Several HPV (human papillomavirus) types are responsible for almost all instances of cervical cancer. It is cited in the research that HPV -16 causes around 50 percent of cervical cancer cases. HPV-18 causes around 20 percent and 10 other carcinogenic types are largely responsible for the other 30 percent.

HPV-16 and HPV-18 are targeted currently by two vaccines available commercially. These are Cervarix by GlaxoSmithKline and Gardasil by Merck.

Presently, these are given prophylactically through three doses over a six month period in a ‘prime-prime-boost’. But Dr Kriemer said their findings suggest that a one-dose schedule should be evaluated further as the amount of HPV vaccine doses necessary to protect women against cervical cancer is questionable.

The researchers have said the collected analysis of two separate trials adds strength to earlier results.

The National Cancer Institute’s Costa Rica HPV Vaccine Trial discovered that young women were exposed to equal protection against HPV-16 and -18 for at least four years following vaccinations of one, two or three doses.

The analysis collected data from this trial, which involved 7,466 healthy women aged between 18 and 25, with results from the PATRICIA trial which involved 18, 644 healthy women aged between 15 and 25.

Both of these trials had a randomized pattern to test the vaccine involvement. Women would be given the HPV-16 or -18 vaccine or a control vaccine at the start of the trial, after one month and after six months. However, some of the participants were given fewer than three doses due to pregnancy stopping the schedule of their immunization.