Costa Rican study shows vaccines prevent but do not treat HPV

A US National Cancer Institute study published in the Journal of the American Medical Association (JAMA) has suggested that vaccines which prevent infection from two strains of the human papillomavirus virus (HPV) responsible for most cases of cervical cancer offer no benefit as a treatment for women already infected with the virus.

Study head, Dr Allen Hildesheim, said: "You should not get the vaccine because you want to treat an existing infection."

Hildesheim added that Merck & Co.'s marketed Gardasil and GlaxoSmithKline's pre-marketed Cervarix have raised awareness about the link between the sexually transmitted human papillomavirus and cervical cancer, but have also raised questions about existing HPV treatment efficacy.

Hildesheim's team studied Cervarix in Costa Rica in 2,189 women aged 18 to 25 who were positive for HPV infection. The vaccine showed no sign of clearing the infection any faster than a placebo.

Merck and GSK admit their vaccines are not intended to treat HPV infections and that Hildesheim's findings confirm existing research.

Gardasil and Cervarix protect against HPV strains 16 and 18 that cause about 70 per cent of cervical cancers. Gardasil also protects against HPV strains 6 and 11. It is approved in the US for females aged between nine and 26.

Hildesheim says his study highlights the importance for early vaccination, but said there was no evidence that the vaccine might protect previously infected women from future infections and help reduce the risk of cervical cancer.