Merck & Co. (MRK:US)’s Gardasil, the human papillomavirus vaccine to prevent cervical cancer, was shown to be safe in the second large-scale study in the past year of side effects since the drug was approved six years ago.
Fainting and infection were among short-term side effects in a U.S. government-required study of 190,000 females in Kaiser Permanente’s California insurance system who were tracked for 60 days after receiving the HPV vaccine. The study today in the Archives of Pediatric & Adolescent Medicine showed patients were six times more likely to have fainted the day of the shot than in the following weeks and 1.8 times more likely to report a skin and subcutaneous tissue infection in the two weeks after.
Gardasil sparked debate in 2007 as 24 states introduced legislation to mandate HPV shots for school girls, despite the lack of long-term safety studies. U.S. Representative Michele Bachmann of Minnesota brought the issue back to light last year at a Republican presidential debate, when she chastised Texas Governor Rick Perry for requiring girls in his state to be vaccinated. Today’s report is the second to be published in the past year to show no significant side effects.
“The take-home message is this is a very reassuring finding,” said Nicola Klein, the study’s lead author and co- director of the Kaiser Permanente Vaccine Study Center in Oakland, California. “Patients and providers should be aware to follow the Centers for Disease Control and Prevention guidelines for 15 minutes after this vaccine.”
The CDC recommends, and Gardasil’s prescribing information suggests, patients be monitored for 15 minutes after they receive the vaccine.
Merck had committed to studying the short-term safety of the HPV vaccine when the Food and Drug Administration approved Gardasil in 2006. Kaiser conducted the study in today’s report with the input of Whitehouse Station, New Jersey-based Merck.
Gardasil and GlaxoSmithKline Plc (GSK)’s Cervarix are the only two U.S.-approved vaccines to combat HPV. Merck’s Gardasil generated $1.2 billion in revenue last year, while Cervarix brought in $812 million for London-based Glaxo.
Gardasil, initially approved for females ages 9 to 26, had its use expanded by the FDA to boys and men in 2009 for the prevention of genital warts caused by certain types of HPV. The shot is supposed to be given in three doses over six months. Merck warns about possible pain, swelling, itching, bruising and redness at the injection site as well as fainting.
A study of records from seven large managed care organizations by the Centers for Disease Control and Prevention and Kaiser published a year ago didn’t find a significant increased risk of fainting associated with Gardasil.
Of the 190,000 females in the Kaiser study published today, 44,000 received all three recommended doses.
Some of the criticism of Gardasil has to do with the potential for long-term side effects that haven’t been examined as thoroughly. Government watchdog Judicial Watch said a review of adverse events reported to the FDA found the vaccine was associated with 26 deaths in the year ending Sept. 15, 2011, as well as seizures, paralysis and blindness.
The Kaiser review board determined that increases during its study in the likelihood of experiencing epilepsy or convulsions after the injection weren’t associated with Gardasil, Klein said. The review board also analyzed 14 deaths and determined they weren’t associated with the vaccine, Klein said. The shots were given between August 2006 and March 2008.
“I think they truncated their conclusions,” said Diane Harper, a University of Missouri-Kansas City professor who worked on Gardasil trials. “The biggest concern of all of these is neurologic that are most rare and most hard to define.”
She singled out a rare condition known as Guillain-Barre Syndrome, in which the immune system attacks the nerves leading to paralysis.
“It doesn’t rule out that any of these effects could still be coming,” Harper said in a telephone interview.
Kaiser said its study “may have had insufficient power to detect very rare conditions.”
Merck is required to conduct a long-term effectiveness study in males and a short-term safety study with another managed care organization, according to an FDA database of post- market commitments. Merck also must collaborate with cancer registries in Sweden, Norway, Iceland and Denmark to assess long-term outcomes following Gardasil use.
Human papillomavirus is the most common sexually transmitted infection. About 20 million Americans have the virus, according to the CDC. The types of the virus that can cause cancer are not the same types that can cause genital warts. About 12,000 women get cervical cancer each year in the U.S. and about 1 percent of sexually active adults have genital warts, according to the CDC.
“Cervical cancer is not a health crisis in any developed country in the world,” said Norma Erickson, president of SaneVax, an advocacy group that highlights the risks associated with the HPV vaccine and has asked the FDA to rescind Gardasil’s approval. “It’s preventable with noninvasive PAP smears. For some reason we’re promoting universal vaccination of girls and boys for something that is already preventable.”
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