By Kathryn Doyle
NEW YORK (Reuters Health) - In a large study of nearly a million girls in Denmark and Sweden, the human papillomavirus vaccine was not linked to short- or long-term health problems.
The HPV vaccine, given in three doses over a period of six months to boys and girls around age 12, protects against infection by a virus that can cause cervical cancer.
"There were not really any concerns before our study and no new ones after," Lisen Arnheim-Dahlström said. She led the study at the Karolinska Institutet in Stockholm.
The new study used national data from both countries to investigate how many girls ages 10 to 17 were diagnosed with any of 53 autoimmune or neurological problems, including celiac disease, pancreatitis, rheumatoid arthritis, psoriasis and narcolepsy. It also looked at whether girls developed blood clots shortly after vaccination.
More than 997,000 girls were diagnosed with the conditions on the list between 2006 and 2010 and more than 296,000 of them had received at least one HPV vaccine dose. Some 160,000 girls had received all three doses.
According to the results published in BMJ, there was no link between the type or timing of the girls' health problems and whether they had gotten the vaccine within the previous six months or had ever received the vaccine.
Previously, isolated incidents of blood clots or other problems had been pegged to the vaccine, but this large new study did not find any negative health consequences, researchers said.
The responsibility for safety is highest when you're giving a drug to people who are well, said Dr. Mark Schiffman, a senior investigator at the National Cancer Institute who was not involved in the new study.
Though his research centers on cervical cancer, Schiffman himself was a "late adopter" of the HPV vaccine. He told Reuters Health he did not have his young daughter vaccinated when the shots were first approved.
Drug approval trials are often too small to detect whether a dose given to millions of people might negatively affect one or two, he said. Those kinds of small associations can only be found after the drug has been used in a large population.
More than 100 million doses have been administered worldwide since the first HPV vaccine was approved in 2006.
"I'm now convinced," Schiffman said. "I recommend to other near and dear friends and family that the vaccine is, to my mind, safe."
He has now vaccinated his daughter and would recommend that every girl get the vaccine.
"Here in Australia physicians (and the community) have been very supportive of the vaccine right from the beginning," Dr. Julia Brotherton wrote to Reuters Health in an email. "There were certainly parents who were hesitant at the beginning because it was a new vaccine, but it is no longer a new vaccine and the impacts of the vaccine in Australia are already significant."
Brotherton is Medical Director of the National HPV Vaccination Program Register in Australia, where there have been very few cases of genital warts in young women since the vaccine was introduced and a reduction in precancerous cervical lesions, she said.
She was not involved in the new study but wrote an accompanying editorial in BMJ.
A general fear of what is new and unknown is not a good reason to skip vaccinations, Brotherton said.
There isn't as much evidence to call on for side effects or health consequences for boys, but the side effect profile is in all likelihood the same, she said.
"Vaccination is always an individual decision," she said. "But as clinicians and public health physicians we can confidently advocate for using the vaccine to prevent people from being infected with this cancer causing virus."
"This opportunity to prevent disease and death from infectious disease that in the past killed or injured millions of people using the vaccines we have available today is truly the best gift you can give your kids."
SOURCE: http://bit.ly/1gpPgDb BMJ, online October 9, 2013.