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Is the HPV vaccine effective after just one dose?
Instead of the hitherto recommended two human papillomavirus (HPV) vaccination schedules, a single vaccine with the HPV vaccine Cervarix may be sufficient to achieve good vaccine protection, according to a recent research led by epidemiologist at the US National Cancer Institute (NCI). The research team around Prof. Dr. med. Cosette Wheeler from the University of New Mexico, Albuquerque, USA; Aimée Kreimer of the US National Cancer Institute (NCI) has published the results of his study in the journal "Lancet Oncology".
According to the researchers, recent studies have suggested that one or two doses of the HPV vaccine already provide similar protection to three doses. Based on the data from the so-called Costa Rica Vaccine Trial and the PATRICIA study, they therefore examined the efficacy of the vaccine against the two HPV types 16 and 18 after one, two and three vaccinations. In this country, the HPV vaccine since last year by the Standing Vaccination Commission (STIKO) recommended for girls aged 9 to 14 years, with two vaccination dates are provided. For older girls, the STIKO provides three vaccinations to achieve adequate vaccination protection. As vaccines Gardasil and Cervarix are approved in Germany.
In particular, HPV vaccination should protect against HPV types 16 and 18, as these are considered to be potential triggers for cervical cancer. (Image: rob3000 / fotolia.com) Recommendation on HPV vaccine controversial
In principle, the HPV vaccine can only have an effect if the patients were previously not infected, which is why the STIKO decided last year to reduce the vaccination age. Because the vaccine should be done before a possible first infection - ie before the first sexual intercourse. However, to date it is still quite controversial to what extent the vaccine makes sense at all, because with the help of appropriate contraception (condoms), the risk of infection can be minimized and also by the so-called PAP test (smear tests of the cervix), the cervix cancer risk is reduced , Despite the criticisms frequently expressed, the STIKO has upheld its recommendation so far, but an adaptation of the proposed doses could possibly follow, if the current results of the US scientists also confirm in further studies.
Indications of adequate protection after one to two vaccinations
The Costa Rican Vaccine Trial, with 7466 participating women between the ages of 18 to 25 years, has already indicated that one or two vaccines could have the same protective effect as three doses, according to the researchers. However, many of the participants were already sexually active before the vaccination, which affected the validity 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). For example, the current study is based on data from a total of 24,055 women, of whom 1,183 received only two and 543 received only one dose.
Further studies are needed to assess HPV vaccination
In terms of infections with HPV types 16 and 18, the efficacy of the vaccine was 77 percent for three doses, 76 percent for two doses and 85.7 percent for one dose, the researchers report. Although vaccination was reversed in other types of HPV, cervical cancer is considered to play a prominent role in both types of HPV. The vaccinations must therefore ensure sufficient protection, in particular before HPV 16 and 18. "Four years after the vaccination of women aged 15 to 25 with one or two doses of the HPV 16/18 vaccine, similar good protection seems to be achieved as with the three-dose regimen," the researchers write. Now further studies are needed to directly assess the efficacy of the HPV 16/18 vaccine after one dose. If these turn out to be positive, an adaptation of the vaccination recommendation would be urgently required, at least on this point. (Fp)