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Questions have emerged in the United States and Australia about the effectiveness and possibly dangerous side effects of Gardasil, Merck's newly licensed vaccine for human papillomavirus.
In the US, three deaths closely time related to immunisation with the vaccine were among 1637 adverse reactions reported by Judicial Watch, a public interest watchdog. Judicial Watch obtained the reports from the Food and Drug Administration using the Freedom of Information Act. The reports were filed through the FDA's vaccine adverse event reporting system.
In Australia, 25 girls at a Catholic high school in Melbourne who had just received their first injection of the vaccine on 22 May experienced headache, nausea, and dizziness, the Age reported. Four were sent to hospital and two were admitted overnight. All were discharged. One expert called it mass hysteria. Shares of the vaccine's Australian developer, CSL, fell after news reports of the incident (www.theage.com.au, 25 May, “Why are we experimenting with drugs on girls?”).
The FDA approved the vaccine in June 2006, and an advisory committee of the Centers for Disease Control and Prevention unanimously voted to recommend it for girls aged 11 and 12 years. It is effective against human papillomavirus types 6, 11, 16, and 18, which cause most cervical cancers and genital warts.
The vaccine has been controversial because some parents objected to state mandates to give it to young girls, preferring to encourage their daughters to abstain from sexual activity until marriage (BMJ 2007;334:721-3 doi: 10.1136/bmj.39164.510127.AD).
Judicial Watch reported on 23 May that the three deaths included one poorly documented death from a blood clot three hours after receiving the vaccine and two deaths in young women with existing heart or clotting problems.
Some 371 of the other adverse reactions reported were serious, including paralysis, Bell's palsy, and Guillain-BarrÃ© syndrome. Among 42 pregnant women who were vaccinated, 18 had side effects, ranging from spontaneous abortion to fetal abnormalities. Most of the adverse effects were typical, such as pain, fever, nausea, dizziness, and itching. Merck warns about such side effects in its prescribing information.
Last month the New England Journal of Medicine published two studies showing that the vaccine was effective (2007;356:1915-27, 1991-93). It reduced the risk of lesions caused by the most dangerous strains, 16 and 18, by 44% but reduced the number of lesions caused by all strains by only 17%. An editorial commented that the modest reduction might be because some women had previously been exposed to the virus or because other strains of virus might have caused lesions when infection with the more dangerous strains was prevented.
The BMJ twice asked Merck to comment on the Judicial Watch report but had not received a response before going to press.