Vaccination mot Humant Papillomvirus - vem bör vaccineras?
Background: Infection with Human Papillomavirus, HPV, is one of the world's most common sexual transmitted infections. The virus causes genital warts (condyloma) but certain virus types can cause cancer. The most common cancer type caused by the virus is cancer of the cervix. Nowadays there is a screening program for women between 23 and 60 years of age where Pap smears of the cervix is taken to discover abnormalities at an early stage. Cervical cancer is very common all over the world and this screening program saves many lives, but not in the less developed countries since the screening program is too expensive. A vaccine has been developed against the four most common HPV- types 6, 11, 16 and 18, and the vaccine costs less than the screening program, so it is now possible to save lives worldwide. The vaccine contains virus-like particles, VLP's, synthesized by L1-proteins from HPV types 6, 11, 16 and 18. HPV 6 and 11 are associated with the sexual transmitted disease condyloma, and HPV 16 and 18 can cause cancer in the cervix among women, but also other kinds of anogenital cancer types. Today, the HPV vaccine is included in the general vaccination program for girls in 5th and 6th grade in Sweden, but not for boys. The risk to get infected with the virus is equal between girls and boys and this has raised the question whether or not boys should be included in the general HPV-vaccination program as well.Purpose: The aim of this study was to evaluate whether or not there is evidence that suggest vaccinating other populations than young girls.Methods: The study is a literature study of clinical trials collected from the database PubMed.Results: Many clinical trials, where the vaccine efficacy among young initially HPV-naive girls have been evaluated, have been performed. They show that the vaccine is effective in preventing HPV-infection in this population. In a population with older participants, that have been sexually active and, thereby, are likely to have been infected with the virus, the vaccine's efficacy is more unknown. Clinical trials have been made in populations like this, with participants with initially unknown HPV-status, and the vaccine shows efficacy against infection with the HPV type, or types, that the individual is not already infected with. Clinical trials have also been made among boys and young men and the vaccine's efficacy is noninferior among men compared with the vaccine efficacy among girls and young women.Conclusions: Those findings support the inclusion of boys in the general vaccination program. They also show that already infected individuals can take benefit from the vaccine since it is not very likely that they are infected with all four vaccine types. But, before a gender neutral vaccination can be recommended, and before vaccination of already infected individuals is suggested, more and larger studies must be made. The new trials should also have longer follow up-times to determine whether a refill vaccination in the future will be needed.