WebMD Medical News
Louise Chang, MD
July 8, 2008 -- The vaccine Gardasil is making headlines -- but this time,
it's about reported side effects and safety concerns.
The CDC and FDA have gotten 7,802 reports of adverse events in people who
were vaccinated with Gardasil, the first cervical cancer vaccine,
between June 8, 2006, and April 30, 2008. And two lawsuits have been filed,
according to media reports, over Gardasil's safety.
Gardasil hasn't been proven responsible for any reported adverse events.
Is Gardasil safe? And what should parents do if they're concerned about
letting their daughter get vaccinated with Gardasil?
WebMD contacted the CDC, Merck (the drug company that makes Gardasil), and an
independent expert who's closely following Gardasil for their answers. But
first, here's a quick recap of Gardasil's history.
(Have you considered giving your daughters the HPV vaccine? We're
discussing it on WebMD's Parenting:
Preteens and Teenagers board.)
June 2006, Gardasil hit the market as the first cervical cancer vaccine.
Gardasil targets four strains of human papillomavirus (HPV) linked to many, but
not all, cervical cancers and to genital warts.
Safety data reviewed by the FDA in approving Gardasil was based on about
11,000 people. Most side effects were mild or moderate reactions, such as pain or tenderness at the
January 2007, the CDC added Gardasil to its routine childhood immunization schedule. The CDC
recommended Gardasil, given in three doses, for all girls aged 11-12 and even
for girls as young as 9, with catch-up doses for girls and women aged 13-26 who
hadn't been vaccinated earlier.
More than 26 million doses of Gardasil have been distributed worldwide,
including nearly 16 million in the U.S., according to Merck, which estimates
that at least 8 million females in the U.S. have received their first dose of
The CDC and FDA monitor adverse events reported in people who get any
vaccine, including Gardasil. All those reports go into the Vaccine Adverse
Events Reporting System (VAERS).
The 7,802 adverse events reported to VAERS for Gardasil include 15 deaths
and 31 reports of Guillain-Barre syndrome, a potentially paralyzing,
life-threatening condition in which the body's immune system attacks part of
the nervous system.
But the VAERS data doesn't tell the whole story, notes John Iskander, MD,
MPH, the CDC's acting director of immunization safety.
"VAERS receives unconfirmed reports of possible side effects" that may
require further study, Iskander tells WebMD. That is, the reports don't show
whether Gardasil caused the reported problems. Publicity tends to increase
VAERS reports, and Gardasil has gotten a lot of publicity, says Iskander.
The serious reported events are about half of what's average for vaccines
overall, according to the CDC.
The CDC hasn't been able to establish Gardasil's role in 10 of the deaths
reported to VAERS; patient information wasn't available for the other five
"Nonserious events" such as pain at the injection site and fainting made up
93% of the reported Gardasil adverse events in the VAERS database, says
He notes that teens are particularly likely
to faint after any vaccination, not just with Gardasil. The CDC recommends that
health care providers
observe patients for 15 minutes after vaccination with any vaccine. As for the pain reports, Gardasil "does
seem to cause a bit more discomfort to some people, compared to some of the
other vaccines given to teenagers," says Iskander.
Merck, which continues to monitor Gardasil's adverse events, stresses the
fact that adverse event reports don't amount to proof of cause and effect.
Karen Smith-McCune, MD, PhD, associate professor of the department of
obstetrics, gynecology, and reproductive science at the University of
California, San Francisco, agrees that the VAERS data don't amount to
But Smith-McCune, who has daughters in the age range for Gardasil
vaccination, says she's waiting to see the final, published results from
Gardasil's phase III clinical trials before she decides whether to let her
daughters get vaccinated.
Merck presented those results to the CDC's Advisory Committee on
Immunization Practices (ACIP) in February and plans to publish the findings
later this year, Merck spokeswoman Amy Rose tells WebMD by email.
"That's great," says Smith-McCune. "Until we see the published,
peer-reviewed final results from phase III trials, we don't have the gold
standard of evidence for safety and efficacy."
Smith-McCune co-wrote an editorial in The New England Journal of
Medicine in May 2008 recommending a cautious approach to the promising and
apparently safe vaccine.
Iskander recommends that parents review the CDC's vaccine
information statement on Gardasil and then make their decision about their
"I think two years of post-licensure safety monitoring is really a good
track record," says Iskander, who says he gives Gardasil in his clinical
practice and abides by what patients decide about Gardasil vaccination.
"Neither providers nor patients should be making decisions based on unfounded
SOURCES:CDC: "Gardasil Vaccine Reports to VAERS."News release, FDA.John Iskander, MD, MPH, acting director for immunization safety, CDC.Merck.WebMD Public Information from the U.S. National Institutes of Health: "What
is Guillain-Barre Syndrome?"Karen Smith-McCune, MD, PhD, associate professor of the department of
obstetrics, gynecology, and reproductive science, University of California, San
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