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Young women in Australia who got a vaccine to prevent cervical
cancer were five to 20 times more likely to have a rare but severe
allergic reaction than girls who got other vaccines in comparable
school-based vaccination programs, researchers said.
They said the severe allergic reactions to the human papillomavirus
or HPV vaccine were unusual and manageable and that the vaccine
remained safe.
The team of Australian researchers led by Dr Julia Brotherton of
The Children's Hospital at Westmead studied 114,000 young women
vaccinated with Merck & Co's Gardasil vaccine as part of a 2007
vaccination program in New South Wales.
Of these, 12 had suspected cases of anaphylaxis, a potentially
life-threatening allergic reaction that can cause difficulty
breathing, nausea and rashes, they reported in the Canadian Medical
Association Journal.
Eight out of the 12 young women had confirmed anaphylactic
reactions after getting the vaccine, for an estimated rate of
reaction of 2.6 per 100,000 doses administered. That compared with
a rate of 0.1 per 100,000 doses in a 2003 school-based meningitis
vaccination program.
Brotherton and colleagues suspect the higher rates of allergic
reaction could be due to better surveillance programs to watch for
such reactions, the higher tendency for young women to have such
reactions compared with men and an apparent overall rise in the
incidence of anaphylaxis in Australia.
Nevertheless, they said that the rates remain rare and should not
discourage use of the vaccine, which targets four strains of the
human papillomavirus, a common sexually transmitted virus that
causes genital warts and most cases of cervical cancer.
"It's just a reminder that there are rare adverse effects," said Dr
Neal Halsey of Johns Hopkins University in Baltimore, who wrote a
commentary on the study.
"It doesn't change the strong recommendations for all adolescent
girls to get this vaccine but we just have to watch them to make
sure they don't have this allergic reaction," he said in a
telephone interview.
Last May, the US Centers for Disease Control and Prevention said
Gardasil has been associated with a higher risk of fainting, in
some cases resulting in injury.
In the United States, Merck has distributed more than 16 million
doses of Gardasil, which is approved for women and girls ages 9 to
26.
