The New England Journal of Medicine published a study on the efficacy of Merck’s expensive and heavily marketed Garasil vaccine. Gardasil is intended to protect young women (and men) against an HPV virus that is a major cause of cervical cancer. The studies find that the vaccine is very effective against young people who have not been previously infected with this sexually transmitted virus. However the NEJM editorializes that

Although this is a remarkable achievement, the efficacy of the vaccine is limited by at least these two factors. First, not all cervical cancer is caused by HPV-16 or HPV-18, and second, it appears necessary to vaccinate young women before they are infected with these two serotypes. Also, whether this approach will extend the paradigm of vaccination to the prevention of death and disability from cervical cancer is an unanswered question.

[C]orrelation with the ultimate outcome — cancer prevention — will require the long-term observation of a large number of treated women. We must also carefully monitor for unintended adverse consequences of vaccination.

Many other questions are raised by these remarkable data. Should young men be vaccinated? What is the durability of immune protection? Could fewer than three vaccinations provide adequate protection? Will future HPV vaccines extend protection to cover additional pathogenic serotypes? Will the economics allow this therapy to reach all who may benefit, such as those in the developing world? Might HPV vaccination be beneficial in preventing other, noncervical HPV-induced cancers (such as HPV-related oropharyngeal cancer)?

The last sentence of this quote relates to another article in this NEJM issue about a study associating these HPV viruses with throat cancer, e.g. oral sex can cause throat cancer.