HPV

Arrancou em 27.10.08, a vacinação contra as infecções por Vírus do Papiloma Humano (HPV), destinada às jovens portugueses que completem 13 anos até ao final do corrente ano.
A integração desta vacina no Plano Nacional de Vacinação foi anunciada pelo primeiro ministro, José Sócrates, com pompa e circunstância (nov 07). Tendo o Governo disponibilizado para já 14 milhões de euros para aquisição da vacina Gardasil. A fornecer pela Sanofi Pasteur, seleccionada através de concurso público (55 euros a unidade) derrotando na negociação final a proposta da GSK (39,39 euros), devido à quadrivalência da vacina apresentada a concurso(protecção dos tipos 16, 18, 06 e 11 do HPV) .

No comunicado da DGS pode ler-se: link
«A vacina Gardasil é a única vacina contra infecções por Vírus do Papiloma Humano (HPV) licenciada nos EUA, tendo já sido comercializadas, em todo o Mundo, mais de 36 milhões de doses.
Assim, com base na evidência científica existente à data e disponibilizada por instituições de referência mundial (CDC e FDA), a DGS, em articulação com o INFARMED, considera que a vacina Gardasil® é segura e efectiva.
Por esta razão, a DGS mantém a recomendação de vacinar, no âmbito do Programa Nacional de Vacinação, as jovens de 13 anos de idade.» Comunicado da DGS

Há, porém, quem não partilhe do optimismo da DGS no que concerne à evidência cientifica dos resultados da vacina link

(...) Despite great expectations and promising results of clinical trials, we still lack sufficient evidence of an effective vaccine against cervical cancer. Several strains of human papillomavirus (HPV) can cause cervical cancer, and two vaccines directed against the currently most important oncogenic strains (i.e., the HPV-16 and HPV-18 serotypes) have been developed. That is the good news. The bad news is that the overall effect of the vaccines on cervical cancer remains unknown. As Kim and Goldie1 point out in this issue of the Journal, the real impact of HPV vaccination on cervical cancer will not be observable for decades.(...)

In the meantime, there has been pressure on policymakers worldwide to introduce the HPV vaccine in national or statewide vaccination programs. How can policymakers make rational choices about the introduction of medical interventions that might do good in the future, but for which evidence is insufficient, especially since we will not know for many years whether the intervention will work or — in the worst case — do harm? (...)

The model presented by Kim and Goldie is well done and ambitious, and it includes most of these factors. They conclude that under certain assumptions, vaccinating 12-year-old girls is associated with an incremental cost-effectiveness ratio of $43,600 per QALY gained, whereas adding a catch-up program for older girls and women is not cost-effective. However, their base-case assumptions are quite optimistic. They presume lifelong protection of the vaccine (i.e., no need for a booster dose), that the vaccine has the same effect on preadolescent girls as on older women, that no replacement with other oncogenic strains of HPV takes place, that vaccinated women continue to attend screening programs, and that natural immunity against HPV is unaffected. Whether these assumptions are reasonable is exactly what needs to be tested in trials and follow-up studies. If the authors' baseline assumptions are not correct, vaccination becomes less favorable and even less effective than screening alone. For example, as shown in the article, if the protection of the vaccine wanes after 10 years, vaccination is much less cost-effective and screening is more effective than catch-up programs.
With so many essential questions still unanswered, there is good reason to be cautious about introducing large-scale vaccination programs. Instead, we should concentrate on finding more solid answers through research rather than base consequential and costly decisions on yet unproven assumptions. "Human Papillomavirus Vaccination — Reasons for Caution", Charlotte J. Haug, M.D., Ph.D. nejm 21.08.08

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