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One or two doses of HPV jab may be enough

Three doses of Cervarix may not be needed for HPV protection

Louise Prime

Saturday, 10 September 2011

Just one or two doses of the human papillomavirus (HPV) vaccine Cervarix may give as effective protection as three doses against cervical cancer, shows research published today in the Journal of the National Cancer Institute. 

In a trial involving 7466 women in Costa Rica, they were assigned to either three doses of Cervarix, or to a control vaccine. But for reasons such as pregnancy or other involuntary factors, 20% of women in the Cervarix group ended up receiving only one or two doses instead of the three-dose regimen.

Researchers followed the women for four years, and compared rates of persistent infection with HPV16 and HPV18 in women who had received only one or two doses of Cervarix, women who had completed the three-dose schedule, and women in the control group.

To the authors’ surprise, they found similar levels of protection from HPV16 and HPV18 in women who had had one, two or three doses of Cervarix.

They say their results could lead to a change in vaccination policy in areas in which cost, or logistics, are possible barriers to vaccination – potentially allowing far more women to receive one dose, for the same total cost as giving three doses to fewer women.

However, they warn that further research is needed on whether one or two doses give sufficiently good protection from HPV infection in the longer term, compared with three doses.

They conclude: “If randomized studies and cost-effectiveness analyses confirm the benefits of administering fewer doses, and the duration of protection is sufficient, then the need for fewer doses may help make primary prevention of cervical cancer a reality.”

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