A key message Merck likes to repeat in marketing Gardasil is that the vaccine prevents the two strains of HPV that account for about 70 percent of cervical cancer. Of course, that’s not the same thing as saying Gardasil is proven to prevent 70 percent of cervical cancer cases.

In fact, clinical trials showed precancerous lesions showed up only 14 percent less often in vaccinated women than those given a placebo. That’s not a huge difference, although Merck has argued that was among women who already had HPV. Among uninfected women who were vaccinated, 46 percent fewer later developed precancerous lesions.

Not surprisingly, Merck is scrambling to narrow the gaps. The drugmaker is asking the FDA to upgrade the Gardasil label to say the vaccine prevents an additional two strains of HPV - types 6 and 11 - that can lead to cervical cancer. Type 16 and 18 were already approved. If the FDA goes along, this would allow Merck to say Gardasil prevents 80 percent of the kind of HPV that can cause cervical cancer and up to 50 percent of low-grade cervical, vulvar and vaginal lesions.

This isn’t surprising. Merck has previously indicated it planned such a move. But unless the drugmaker does an unlikely about face, its marketing will continue to trumpet such data without acknowleding the low effectiveness against precancerous lesions. For health professionals, the Gardasil onslaught will, therefore, remain a challenge, since pap smears are the best form of detection.

Merck press release.

[tags]Gardasil, HPV, Merck[/tags]