Does Seasonal Influenza Vaccination Affect the Incidence of pH1N1 Influenza?
Condition: Influenza
MeSH terms: Influenza, Human
Study type: Interventional
Phase: Phase 3

Summary: 
      Since the onset of the 2009 pandemic, several observational public health investigations in
      Canada have identified evidence that suggests that adults, particularly younger adults, who
      have previously received seasonal influenza vaccine are at increased risk of infection with
      the 2009 pandemic strain of H1N1 (pH1N1). Investigations in Australia, the United States and
      the United Kingdom have not identified this effect. While it is not possible to have an
      answer to whether this affect is real prior to the second wave of the 2009 pandemic, it
      remains vital to future influenza vaccination programs that the hypothesis that, in 2009,
      seasonal vaccine increases or decreases the risk of pH1N1 infection be confirmed or refuted.

      The objective of this study is to determine whether Ontario adults aged 18-60 years who
      receive the 2009 seasonal influenza vaccine will be at a 2 fold or greater increased risk of
      infection with influenza pH1N1 during the second or third wave of the 2009 pandemic.
    

Detailed description: 
      This study will be an observer -blind randomized controlled trial.

      This study will primarily recruit patients from an existing cohort of adult health care and
      other workers in Toronto, as of September 15, 2009, almost 1000 adults are participating in
      this cohort; with approximately 75 new cohort members being recruited weekly (target is
      1300). Recruitment will be supplemented by enrollment at Hamilton Health Sciences Centre
      (N~3920 employees plus physicians & midwives) and Queen Elizabeth II Health Centre in Halifax
      (N~6000 employees plus physicians & midwives).

      To date, health care workers in the Toronto cohort have been recruited at the Mount Sinai
      Hospital, Toronto East General Hospital, and North York General Hospital. Recruitment is just
      beginning at Sunnybrook Health Sciences Centre, and the University Health Network.

      Non-health care workers are being recruited from several large Toronto employers of primarily
      office workers. These include the Ontario Agency for Health Protection and Promotion, the
      head offices of the Ontario Power Generation Corporation, the Art Gallery of Ontario, and the
      head offices of Scotia Bank. Non-health care workers should meet inclusion criteria and
      should not work primarily with children or from a home office.

      Participants in the study are completing web-based diaries weekly, and, whenever they develop
      symptoms possibly compatible with influenza, are submitting nasal swabs, and completing
      symptom diaries daily while ill. Nasal swabs are tested by polymerase chain reaction (PCR) on
      a same or next day basis with antivirals prescribed to participants who develop influenza.
    

Intervention name(s): Fluviral influenza vaccine, 2009-2010; Normal saline
Intervention type(s): Biological; Biological
Intervention description(s): 0.5 mL intramuscular; 0.5 mL intramuscular
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Health Services Research
Keywords: influenza; vaccine; observer blind