The human papillomavirus vaccine is not linked to an increased risk of autoimmune disorders, according to new Canadian research published on Monday.
Of the nearly 181,000 girls who were vaccinated between 2007 and 2013 in Ontario, only 681 were later diagnosed with an autoimmune disorder, such as rheumatoid arthritis, Bell’s palsy, multiple sclerosis or Guillain-Barré syndrome. The rate of autoimmune-disorder diagnosis among vaccinated girls was similar to the diagnosis rate in the larger population of adolescent girls, the study’s authors said.
“Parents forget that these [diagnoses] can happen, even in girls that aren’t vaccinated,” said Linda Lévesque, a senior study author, an HPV vaccine researcher and a scientist with Ontario’s Institute for Clinical Evaluative Sciences. “When they happen soon after vaccination, I think it’s a natural intuition for parents to blame the vaccination.”
The HPV vaccine, which protects against strains of a virus that can cause cervical cancer, has been given to elementary-school-aged girls for more than a decade. Many provinces have also expanded their vaccine programs to include boys.
The study, published on Monday in the Canadian Medical Association Journal, should provide parents with reassurance the vaccine is safe for their children, Dr. Lévesque said. It’s important to keep demonstrating the safety of vaccines in these types of studies because there are those who continue to stoke fears and claim that vaccines are dangerous, she said. It’s become easier to question vaccinations because this generation hasn’t seen what life without vaccines can be like, Dr. Lévesque added.
“I think the fear comes out of uncertainty,” she said. “If you ask our parents or grandparents, they had no concerns about vaccines because they [lived] the reality of the burden of those diseases. Their children died of these things.”
Parents were “concerned about the safety of the HPV vaccine,” said Erin Liu, a lead author who started the research while doing her master’s in epidemiology at Queen’s University and is now a PhD candidate at McGill University. “This is why we need rigorous scientific studies, to answer those important research questions.”
The study, which used Ontario health data provided by the Institute for Clinical Evaluative Sciences, found the overall incidence of autoimmune disorders among vaccinated girls to be very low. The most commonly diagnosed autoimmune condition in the group was rheumatoid arthritis, followed by immune thrombocytopenia purpura, which is a bleeding disorder, and Bell’s palsy, which can cause facial paralysis. Of the 681 vaccinated girls who were later diagnosed with an autoimmune disorder, just more than 11 per cent were diagnosed within seven to 60 days after vaccination.
The study focused on the quadrivalent HPV vaccine, known as Gardasil and sold by Merck, as it has been available the longest. But there’s no reason to believe other versions of the vaccine have a different risk level, Dr. Lévesque said.
The research was funded by grants from the Ontario Health Ministry’s drug-innovation fund and the Canadian Institutes of Health Research.