New research indicates that Gardasil, the human papillomavirus vaccine is more likely to trigger reportable adverse effects in younger girls than in adult women.
The side effects are non-serious and similar to those associated with other vaccines, according to a new study funded by the Centers for Disease Control and Prevention and published in the Journal of Women's Health
As part of an ongoing study and evaluation of this relatively new vaccine, researchers surveyed 899 girls and young women (ages 11-26) within two weeks after they received the Gardasil vaccine injection in the upper arm. The survey, which took place in 2008, also found that while most girls and young women did know that the vaccine can prevent cervical cancer, and that three doses are recommended, many didn't know that the vaccine can also prevent genital warts and abnormal pap smears.
"Gardasil is an important cancer prevention vaccine, but too few girls are getting it. Our study found that young girls do have some knowledge about the vaccine, but they need to know more. If these girls and their parents know what to expect, they will likely be less afraid of getting the vaccine," said study lead author Allison Naleway, PhD, a senior investigator with the Kaiser Permanente Center for Health Research in Portland, Ore.
Since 2006, the CDC has recommended Gardasil for girls ages 11-12, and for older girls and women (ages 13-26) who did not receive the vaccine when they were younger. The CDC also recently recommended Gardasil for boys ages 11-12, and for older boys and men (ages 13-21) who did not receive the vaccine when they were younger.
Information about side effects has been reported by the manufacturer, the CDC, and by the federal government's Vaccine Adverse Event Reporting System, but this study is one of the first to survey girls themselves shortly after they received the vaccine. Many other studies have relied on information reported by health care providers and parents.
For this study, researchers used electronic health records to identify 3,490 Oregon and Washington girls and young women (ages 11-26) who received their first dose of HPV vaccine between February and September of 2008. Within a week of vaccination, researchers sent out surveys to young women ages 18-26. For girls under 18, researchers notified parents that their daughters would be receiving the surveys the following week, and gave the parents a choice to opt out. The survey included 50 questions about vaccine side effects, about girls' knowledge of the vaccine and the HPV virus, and about what kind of information their doctors shared with them before vaccine administration.
Of the 899 girls and women who responded to the survey, 78 percent reported pain when receiving the vaccine. Seventeen percent reported bruising or discoloration, 14 percent said they had swelling at the injection site, 15 percent reported dizziness, and 1 percent of the girls reported fainting.
Younger girls were more likely to have received other vaccines such as tetanus, meningitis, and hepatitis A at the same time they received the HPV vaccine, and they were also more likely to report side effects. For example, 84 percent of girls aged 11-12 reported pain with the injection vs. 74 percent of women aged 18-26. Nineteen percent of girls aged 11-12 reported feeling dizzy after receiving the vaccine, but fewer than half that many (8%) of women aged 18-26 reported dizziness.
"These side effects are non-serious and very manageable," said Mike Wilmington, MD, a Kaiser Permanente pediatrician in Vancouver, Wash., who was not involved in the study. "The main complaint I hear about is pain with the injection, but there are ways to lessen the pain. Some girls will feel dizzy after this and other vaccines, so I follow CDC guidelines and have them sit or lie down for a few minutes after receiving the vaccine."
Eighty-four percent of girls and young women said they knew that the HPV virus can cause cervical cancer, but only half reported knowing that it can also cause genital warts and abnormal pap smears. Most respondents said their providers told them they needed three doses of the vaccine, and most also said their providers talked with them about the vaccine's benefits, possible side effects, and about HPV infection. Most girls, however, said their providers did not discuss genital warts or abnormal pap smears, and only one fifth of girls said their provider asked them to sit and rest after receiving the vaccination.
Study authors include Allison Naleway, PhD; Rachel Gold, PhD, MPH; Lois Drew; Karen Riedlinger, MPH; and Michelle Henninger, PhD from the Kaiser Permanente Center for Health Research in Portland, Ore., and Julianne Gee, MPH, from the Centers for Disease Control and Prevention in Atlanta.
This study is part of Kaiser Permanente's ongoing research to understand the safety and efficacy of Gardasil. A study of 189,629 girls, teenage girls and young women, published earlier this year in the Journal of Internal Medicine
, found that Gardasil does not trigger autoimmune conditions such as lupus, rheumatoid arthritis, type 1 diabetes or multiple sclerosis after vaccination in young women.