By Roxanne Nelson, staff journalist, Medscape Oncology
January 31, 2012 — Is the policy for the human papillomavirus (HPV) vaccine at odds with evidence-based medicine?
Yes, according to an essay published online December 22, 2011, in the Annals of Medicine.
Canadian researchers Lucija Tomljenovic, PhD, and Christopher Shaw, PhD, from the Neural Dynamics Research Group, University of British Columbia, in Vancouver, point out that there is a major discrepancy in claims regarding the safety and efficacy of Gardasil (Merck & Co) and Cervarix (GlaxoSmithKline) — the 2 HPV vaccines that are currently on the market.
The vaccines have been heavily promoted in the United States by their respective manufacturers, the essayists report. In addition, the vaccines are backed by government agencies in the United States, including the Center for Disease Control and Prevention and the US Food and Drug Administration, and by medical authorities in a number of other countries.
HPV vaccination has been mired in controversy since the first vaccine was approved in the United States in 2006. There have been clashes among politicians, parents, professional and advocacy organizations, and public health officials, with heated exchanges over issues ranging from safety, the premise that vaccination will promote sexual activity in teens, cost, and concerns about aggressive lobbying by Merck to make the vaccine mandatory for girls.
Drs. Tomljenovic and Shaw note that skepticism about the vaccine has been increasing for a number of reasons, despite reassurances from the public-health sector. In their essay, they examine the current evidence to answer a key question: “Is it possible that HPV vaccines have been promoted to women based on inaccurate information?”
Does it Prevent Cancer?
One major issue is the claim made by medical authorities that HPV vaccines are an important tool in preventing cervical cancer. The efficacy of the vaccines in preventing cervical cancer has not been demonstrated because the study periods have been too short, say the essayists.
The longest follow-up from phase 2 trials for Gardasil is 5 years and for Cervarix is 8.4 years, but invasive cervical cancer can take 20 to 40 years to develop from the time of HPV infection.
“We don’t know the duration of the immune response of the vaccines,” Dr. Tomljenovic told Medscape Medical News, “so we don’t know if they are actually preventing cervical cancer or simply postponing it.”