The human papillomavirus (HPV) vaccine has been controversial in both the United States and European countries like Germany. It prevents about 70% of cervical cancers, cervical cancer is uncommon and highly treatable, and it will need another vaccine before girls who are given it even become adults. Along with those data issues, academic scientists and the public have been engaged in a culture war against pharmaceutical companies - that vaccines are exempt from ordinary lawsuits and that the vaccine was marketed heavily just after an expensive settlement by manufacturer Merck was not lost on the public.

One of those concerns, that the vaccine does not last very long, has been addressed in Deutsches Ärzteblatt International (Dtsch Arztebl Int 2014; 111: 584–91). Yvonne Deleré et al. conducted a systematic review and find no decrease in protection over a period of five years following vaccination against HPV types 16 and 18. 

Each year in the United States, 1 in 12,000 females will get cervical cancer but in Germany the rates are higher. Persistent infection with a high-risk human papillomavirus (HPV) type is a necessary prerequisite for the development of dysplasia and neoplasia of the cervix. Vaccines authorized for the German market are targeted against HPV types 16 and 18 because these are two of the most common high-risk types in Germany. Vaccination provides protection before infection with these HPV types, thus preventing HPV infection, without which cervical cancer does not develop.

As sexual contact is the main route of transmission of HPV, vaccination is most effective when performed in girls and young women aged between 12 and 17 who are not yet sexually active. The review focused on studies investigating the efficacy of vaccination in short- and long-term follow-up, is therefore restricted to HPV-naive girls and women.

According to the authors' calculations, in long-term follow-up vaccination is 94% effective in preventing randomly detected infection, 95% effective in preventing persistent infections, and 86% effective in preventing grade 2 or above cervical intraepithelial neoplasia (CIN 2+). However, smaller study and participant numbers mean that the quality of the evidence on long-term protection is lower than that on short-term protection.

In order to improve the quality of evidence on long-term protection, the authors call for continuation of randomized controlled trials to ascertain the duration of HPV vaccine protection and further observational studies assessing the efficacy of vaccination.