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No association of HPV vaccination with serious adverse events

      Arnheim-Dahlström L, Pasternak B, Svanström H, Sparén P, Hviid A. Autoimmune, neurological, and venous thromboembolic adverse events after immunisation of adolescent girls with quadrivalent human papillomavirus vaccine in Denmark and Sweden: cohort study. BMJ. 2013;347:f5906.

      Question

      Among adolescent girls, what is the rate of adverse events in those who received, compared with those who did not receive, the quadrivalent human papillomavirus vaccine (qHPV)?

      Design

      Register-based cohort study.

      Setting

      Denmark and Sweden, October 2006, to December 2010.

      Participants

      997 585 girls aged 10-17 years.

      Intervention

      qHPV.

      Outcomes

      Incident hospital diagnosed autoimmune, neurologic, and venous thromboembolic events. For outcomes where the rate ratio was significantly increased, three criteria were regarded as signal strengthening: (1) analysis based on 20 or more vaccine exposed cases; (2) rate ratio 3.0 or more; and (3) significantly increased rate ratio in country specific analyses.

      Main Results

      Exposure to qHPV was significantly associated with an increase only in Behcet syndrome, Raynaud disease, and type 1 diabetes. Each of these three outcomes fulfilled only one of three predefined signal strengthening criteria. Furthermore, the pattern of distribution in time after vaccination was random for all three.

      Conclusions

      This study found no evidence supporting associations between exposure to qHPV and autoimmune, neurologic, and venous thromboembolic adverse events.

      Commentary

      Despite the recommendation for universal qHPV of adolescent girls in 2007 (and males in 2011), qHPV rates remain substantially lower than other adolescent vaccines (meningococcal and tetanus, diphtheria, and pertussis vaccines) in the US.
      • Centers for Disease Control and Prevention
      National and state vaccination coverage among adolescents aged 13–17 years — United States, 2012.
      Concerns about vaccine safety by parents is a well-known barrier to vaccination in general, but such fear is often heightened for newer vaccines as parents question the extent to which a new vaccine has been tested.
      • Freed G.L.
      • Clark S.J.
      • Butchart A.T.
      • Singer D.C.
      • Davis M.M.
      Parental vaccine safety concerns in 2009.
      This study examines an important issue—the risk of serious adverse events after qHPV among adolescent girls. The setting of the study (Denmark and Sweden) allows for a more robust analysis than previous studies have been able to accomplish by using the national database in each country. The authors used rigorous methods to measure rates of qHPV vaccination and potential adverse events. As the authors note, data on the date of diagnosis of disease or onset of symptoms were not included in this study, but such information would improve our understanding of how many potential adverse events had symptoms prior to vaccination.
      Though many ‘new’ medical interventions draw a healthy dose of skepticism by the public, vaccines suffer a disproportionately high burden of distrust. The study by Arnheim-Dalström et al is an important contribution to the growing literature about the safety of qHPV.However, because fear sits much deeper than logic in hearts of parents, we will undoubtedly have to continue to study the safety of this vaccine for years to come.

      References

        • Centers for Disease Control and Prevention
        National and state vaccination coverage among adolescents aged 13–17 years — United States, 2012.
        MMWR. 2013; 62: 685-693
        • Freed G.L.
        • Clark S.J.
        • Butchart A.T.
        • Singer D.C.
        • Davis M.M.
        Parental vaccine safety concerns in 2009.
        Pediatrics. 2010; 125: 654-659