Despite growing concerns about the side effects of Gardasil -- a new vaccine manufactured by Merck and Co. that targets the human papillomavirus, a sexually transmitted disease -- Dartmouth Medical School professor Diane Harper recommends women take the drug as one of a number of preventative measures against HPV, which has been shown to cause cervical cancer. Harper led HPV vaccine clinical trials for Merck.
A June 30 statement by the U.S. Food and Drug Administration sparked the recent controversy over the vaccine. The FDA's statement highlights the more than 9,700 side effects that have been recorded since the drug's release two years ago. About 94 percent of these adverse effects were "non-serious events," while 6 percent were severe.
Harper said she believes there are side effects, but that major adverse effects are rare. Of the millions women who have already received the vaccine, she said, only a small number of women have experienced serious adverse effects.
"As with any drug, there are side effects, and the side effects are starting to come out with Gardasil, but they rarely happen," she said. "A young woman between the ages of 15 and 26 can say, 'Yes, I think that protection against this virus is an important thing for me and my health and I'm willing to accept any side effects that might happen.'"
In response to uproar from patients, doctors and Merck following its June review of the vaccine, the FDA joined with the Centers for Disease Control and Prevention to issue a statement on July 22 that says Gardasil is safe, despite the prevalence of side effects.
"Based on the review of available information by FDA and CDC, Gardasil continues to be safe and effective, and its benefits continue to outweigh its risks," the statement said.
The FDA and the CDC have stated the 20 deaths originally linked to the vaccine may not have been caused by Gardasil, according to autopsy reports. In addition, vaccinated patients who later developed Guillain-Barre Syndrome, a serious neurological disorder, do not appear to have developed the disease because of Gardasil.
Merck stated most of the adverse events were non-serious and typically consisted of dizziness and fainting, according to a response the company sent to the FDA. The response also states that serious side effects, such as death and paralysis, are not necessarily attributable to the vaccine.
Harper, who helped test the drug before its release in 2006, agreed.
"The biggest reported [side effect] is numbness and tingling in hands and feet," she said. "What is not true is that every single person who gets Gardasil is going to become paralyzed or die from it."
While Gardasil does protect against four strains of HPV -- two of which are responsible for 70 percent of cervical cancer in females -- women may still become infected, according to McGill University professor Abby Lippman, who is not involved in the vaccine studies. There is not enough evidence about the vaccine's effectiveness to advocate for or against receiving it, she said. Unlike sweeping epidemics such as polio, the disease is not spreading at a quick enough rate to require immediate widespread use of the vaccine, she added.
"I wave the yellow flag: I neither say do it or not do it," Lippman said. "We're talking about a very slowly progressive disease for which we have secondary prevention, so that's why I'm saying we need not race to use a primary tool until we have more information on a public health basis."
More testing is needed to explore Gardasil's short- and long-term side effects, Lippman said.
Because overall effectiveness of the vaccine is still unknown, women who receive the drug should continue to get Pap smears, according to Harper. This contradicts Merck's advertisement of Gardasil, she said, which gives the impression that the drug cures all forms of cervical cancer.
"What Gardasil is going to do is give you a reassurance that all the screens you continue to get are going to be closer to normal," Harper said. "The message that people perceive from [Merck's] adds is that if they get this vaccine they will be prevented from getting cervical cancer. That is not true."
