The quadrivalent vaccine against human papillomavirus (HPV) is associated with an increased risk of fainting on the day of the shot and of skin infections in the 2 weeks afterward.
Aside from that, a large retrospective study of nearly 190,000 girls and young women "did not detect any evidence of serious safety concerns" associated with the vaccine, according to Nicola Klein, MD, PhD, of the Kaiser Permanente Vaccine Study Center in Oakland, and colleagues.
Action Points
- Explain that a Kaiser Permanente study found that only fainting on the day of vaccination and skin infections within 14 days of vaccination were safety outcomes of interest following administration of the quadrivalent human papillomavirus (HPV) vaccine to a large cohort of young women.
- Note that this was a post-licensing study for adverse events resulting in an emergency department visit or hospitalization for those receiving at least one dose of the vaccine.
The study, sponsored by the vaccine's maker, was conducted as part of post-licensing requirements, they reported online in Archives of Pediatrics & Adolescent Medicine.
The findings "support the general safety" of the vaccine in routine clinical care, the researchers concluded.
For the analysis, Klein and colleagues looked at medical records of 189,629 females, ages 9 to 26, who were enrolled in the healthcare systems of Northern and Southern California Kaiser Permanente and got at least one dose of the vaccine between August 2006 and March 2008.
The study began just after the vaccine was approved and continued until 44,000 participants got three doses on the recommended schedule – the so-called "3-dose population."
They were a subset of the larger "any-dose" population of women who had at least one dose, including some who got two doses and some who got three but not on the recommended schedule.
Klein and colleagues used the medical records of the vaccinated women and girls to examine the risk of emergency department visits and hospital admissions that occurred on the day of the shot, within 14 days, or within 60 days.
Using diagnostic codes, they compared rates of events within those periods to rates in subsequent periods separated by 180 days for the 3-dose population and by at least 60 days and as much as 180 days for those in the any-dose group.
Overall, they found, 50 diagnostic categories had significantly elevated odds ratios but medical record review revealed that most were either present before vaccination or that the diagnostic workups began at the vaccine visit.
An independent safety committee determined that only skin infections during days 1 to 14 and syncope on the day of vaccination were likely to be associated with the vaccine.
The odds ratio for skin infections was 1.8, (95% CI 1.3 to 2.4), while the odds ratio for fainting was 6.0 (95% CI 3.9 to 9.2).
The researchers noted that some of the skin infections might have been site reactions to the vaccine.
They also noted that an earlier study did not find an elevated risk of fainting after HPV vaccination compared with vaccination for other reasons, suggesting that in some cases syncope might be a result of receiving a shot, not the vaccine itself.
Indeed, they commented, the association "was not unexpected (because) immunization and injections in general have a known association with syncope (particularly in this age group)."
Klein and colleagues cautioned that the study was designed to look only at new safety signals that made their appearance within 60 days of the vaccination and might have missed longer-term issues as well as events that did not result in an emergency department visit or hospitalization.
And, although the study was large, it might still not have had the power to detect very rare outcomes, they added.
Disclosures
The study was funded by Merck. Klein reported financial links with Merck, GlaxoSmithKline, Pfizer, Novartis, and sanofi pasteur. Several other authors reported financial links with Merck, including two who are employees.
Primary Source
Archives of Pediatrics & Adolescent Medicine
Klein NP, et al "Safety of quadrivalent human papillomavirus vaccine administered routinely to females" Arch Pediatr Adolesc Med 2012; 166(10): 1-9.