Safety profile of quadrivalent human papillomavirus vaccine: Canadian experiences

Purpose: Health Canada approved the use of a quadrivalent vaccine against human papillomavirus (qHPV) in 2006, and by 2010 all Canadian jurisdictions had school-based immunization programs targeting girls. Opponents to these efforts have raised various concerns, particularly around the safety of the vaccine. This paper describes the safety profile of qHPV based on 6 years of reporting to the Canadian Adverse Event Following Immunization Surveillance System (CAEFISS). Data used: Reported adverse events following immunization (AEFIs) following qHPV administration from June 2006 to December 2011 and available in CAEFISS as of December 31, 2012.

Methods: Related CAEFISS AEFI reports were coded using standard terms from the Medical Dictionary for Regulatory Activities (MedDRA) and classified by reason for reporting, time to onset, and severity. Using SAS, descriptive analyses examined key trends and patterns.

Results: By December 2011, with over 3 million doses of qHPV distributed, 1389 AEFI reports involved qHPV. Most commonly reported AEFIs were rash, vaccine site pain and swelling, and non-anaphylactic allergic reactions. 51 AEFIs (3.7 %) met the criteria for serious (≥ 1 outcomes of: hospitalization, prolongation of existing hospitalization, permanent disability, or death). Of these the majority had alternate explanations for the reported event (29) or insufficient information to assess the role of vaccine (18). Events related to vaccination (4) were: post-syncopal head injury, anaphylaxis, myalgia and prolonged injection site pain.

Implications: Post-market experiences with qHPV in Canada are consistent with pre-market clinical trial observations, and match other national experiences and World Health Organization conclusions. Healthcare providers and public health authorities should promote its continued use.