Healthy Skepticism Library item: 10033
Warning: This library includes all items relevant to health product marketing that we are aware of regardless of quality. Often we do not agree with all or part of the contents.
Publication type: news
Carreyrou J, Winstein K.
Medical Journal Questions Efficacy of HPV Vaccine
The Wall Street Journal 2007 May 9
http://online.wsj.com/article/SB117874216633897566.html?mod=wsjcrmain
Full text:
An editorial published in the New England Journal of Medicine raises questions about the overall effectiveness of Merck & Co.‘s cervical-cancer vaccine, Gardasil, and advises policy makers, doctors and parents to adopt “a cautious approach” toward vaccination.
The editorial accompanied a study published in the medical journal analyzing the results of a clinical trial of the vaccine, which targets two types of the human papillomavirus thought to cause most cervical cancers and two other types that cause genital warts. The study, involving 12,167 women, found the vaccine was 98% effective at preventing precancerous lesions of the cervix related to the two cancer-causing types, known as HPV 16 and 18, among a subgroup of women previously uninfected with the virus.
But the vaccine’s efficacy against precancerous lesions related to HPV 16 and 18 fell to 44% among the broader group of women, which included women previously infected with HPV. And the efficacy figure dropped to 17% when all precancerous lesions were taken into account in that broader group. The women were followed for three years following vaccination.
Merck has touted Gardasil as a breakthrough vaccine that may help eradicate cervical cancer, noting that HPV 16 and 18 are thought to cause 70% of cervical cancer cases. But the 17% efficacy figure suggests that the vaccine will have less impact than advertised in the general female population.
In a page one Wall Street Journal article last month, some scientists raised doubts about whether the vaccine will really reduce cervical-cancer rates in the U.S. and suggested the billions of dollars likely to be spent on Gardasil in coming years might be better used to expand Pap screening among low-income women.
Merck aggressively lobbied state legislatures to make vaccination a school requirement for 11- and 12-year-old girls before pulling the campaign in February. Sixteen states are considering making such requirements law, and two, Texas and Virginia, have already acted to do so.
However, Texas has since pulled back. Texas Gov. Rick Perry said Tuesday he wouldn’t veto a bill passed by the legislature blocking state officials from following his earlier executive order mandating vaccination of girls entering the sixth grade. Gov. Perry’s order had come under heavy criticism because he received campaign contributions from Merck and one of Merck’s lobbyists in Texas was the governor’s former chief of staff.
In their NEJM editorial, George F. Sawaya and Karen Smith-McCune, members of the department of obstetrics and gynecology at the University of California, San Francisco, wrote that “a cautious approach” toward vaccination “may be warranted in light of important unanswered questions about overall vaccine effectiveness, duration of protection, and adverse effects that may emerge over time.”
The authors called the vaccine’s overall efficacy against precancerous lesions of the cervix “modest” and theorized that one reason for this limited efficacy might be that other cancer-causing HPV types fill “the biological niche left behind after the elimination of HPV types 16 and 18.” HPV has more than 100 different types, roughly 17 of which are thought to cause cancer.
Eliav Barr, who heads Merck’s HPV vaccine program, has said this phenomenon, known as replacement, is unlikely based on other analyses the company has conducted. Dr. Barr has also defended Gardasil as a “lifesaving” vaccine whose widespread adoption will result in “a substantial decline in the rate of cervical cancer.”
