HPV: effective protection after vaccination?
Instead of the previously recommended two vaccination appointments for protection against human papillomaviruses (HPV), a single vaccination with the HPV vaccine Cervarix may be sufficient to achieve good vaccination protection, according to a recent study led by epidemiologists from the US National Cancer Institute (NCI). The research team led by Prof. Dr. Cosette Wheeler from the University of New Mexico in Albuquerque (USA) and Dr. Aimée Kreimer of the US National Cancer Institute (NCI) has published the results of his study in the specialist magazine "Lancet Oncology".
According to the researchers, more recent studies have indicated that one or two doses of the HPV vaccine already offer protection similar to that of three doses. They therefore used the data from the Costa Rica Vaccine Trial and the PATRICIA study to check the effectiveness of the vaccine against the two HPV types 16 and 18 after one, two and three vaccinations. In Germany, HPV vaccination has been recommended by the Standing Vaccination Committee (STIKO) for girls between the ages of 9 and 14 since last year, with two vaccination appointments scheduled. For older girls, the STIKO provides three vaccinations in order to achieve adequate vaccination protection. Gardasil and Cervarix are approved as vaccines in Germany.
Controversial recommendation on HPV vaccination
In principle, HPV vaccination can only have an effect if the patients were not previously infected, which is why STIKO decided to reduce the age of vaccination last year. Because the vaccination should be given before a possible first infection - i.e. before the first sexual intercourse. However, the extent to which vaccination makes sense remains controversial, since the risk of infection can already be minimized with the help of appropriate contraception (condoms) and, in addition, the risk of cervical cancer is comprehensively reduced by the so-called PAP test (cervical smear tests) . Despite the criticism that has been voiced many times, STIKO has so far adhered to its recommendation, but an adjustment of the proposed doses could possibly follow if the current results of the US scientists are confirmed in further studies.
Indications of adequate protective effect after one or two vaccinations
In the Costa Rica Vaccine Trial with 7,466 women between the ages of 18 and 25 who participated, according to the researchers, there were already indications that one or two vaccinations could have the same protective effect as three doses. However, many of the participants were sexually active before the vaccination, which affected the significance of the study. The US scientists therefore included the data from 18,644 women between the ages of 15 and 25 from the "Papilloma Trial against Cancer in Young Adults" (PATRICIA). The current study can be based on data from a total of 24,055 women, of whom 1,183 received only two and 543 received only one vaccine dose.
Further studies to assess HPV vaccinations are required
Regarding infections with HPV types 16 and 18, the “effectiveness of the vaccine was 77 percent for three doses, 76 percent for two doses and 85.7 percent after one dose,” the scientists report. Vaccination was reversed for other types of HPV, but with regard to cervical cancer, the two types of HPV mentioned play an outstanding role. Vaccinations must therefore ensure adequate protection, especially against HPV 16 and 18. "Four years after vaccinating women 15 to 25 years of age with one or two doses of the HPV-16/18 vaccine, similar protection seems to be achieved as with the three-dose plan," the researchers write. Now further studies are needed to directly assess the effectiveness of the HPV 16/18 vaccine after a dose. If these are positive, an adjustment of the vaccination recommendation would be urgently needed at least on this point. (fp)