Adverse events linked with HPV vaccine appear to be related with media coverage

University of North Carolina's School of Public HealthNov 20 2013

The number of adverse events associated with the HPV vaccine reported to the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) appeared to be related to media coverage and online controversy about the vaccine, finds a study in the Journal of Adolescent Health.

"Vaccines are being met with increased skepticism and criticism in society," said the lead author Jan Eberth, PhD., an assistant professor of epidemiology at the University of South Carolina Arnold School of Public Health.

HPV vaccines prevent infection from certain types of human papillomavirus. A sexually transmitted virus, HPV increases the risk of cervical, oral, anal, vaginal and vulvar cancers in women and of oral, anal and penile cancers in men. The authors noted that because this vaccine concerns sexual activity in young people, public discussion of its use has often been heated.

To determine if there was a connection between media coverage and reported vaccine side effects, the researchers compared the number of adverse effects reported for the HPV vaccine Gardasil® with the number of adverse events reported for Menactra®, a vaccine used to prevent meningitis, a potentially deadly nervous system infection. Menactra is administered to a similar age group as Gardasil and was approved shortly before Gardasil.

The authors compared the amount of print media coverage that the two vaccines received during two and a half years following their FDA approval. The researchers also examined the association between adverse effects reported for each of the two vaccines and the amount of online search activity related to them.

During that time frame, the vaccine adverse event reporting system maintained by the CDC and FDA received a monthly average of 159 adverse reports for Gardasil versus 19 for Menactra. Print media coverage was much heavier for Gardasil, spiking in month nine with 147 media reports. During the preceding 8 months, there was no significant difference in adverse event reports for Gardasil and Menactra.

Adverse event reporting for Gardasil increased nine months after approval. At that time, Texas governor Rick Perry issued an executive order that all girls older than age 11 be vaccinated, an order which the Texas legislature overturned.

The researchers found that the disproportionate number of Gardasil adverse events reported reflected the intense media attention which echoed after the Texas controversy moved online. Though the authors admit they cannot rule out an actual difference in the number of side effects experienced from the two vaccines, they note that the reported risk of serious adverse events for both Gardasil and Menactra were low (.8 percent vs. 1.0 percent).

The sheer volume of media coverage for the HPV vaccine versus the low coverage for the meningitis vaccine may have raised awareness of potential adverse events and the need to report them, said the authors. They suggest that public health communicators who explain vaccines need to pay closer attention to information spread in the media and online forums.