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Fever and febrile seizures in NZ children following 2010 trivalent inactivated influenza vaccines. Helen Petousis-Harris, Nikki Turner , Tracey Poole, Department of General Practice and Primary Health Care Immunisation Advisory Centre University of A uckland.
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Fever and febrile seizures in NZ children following 2010 trivalent inactivated influenza vaccines Helen Petousis-Harris, Nikki Turner, Tracey Poole, Department of General Practice and Primary Health Care Immunisation Advisory Centre University of Auckland Co-investigators: Robert Booy, Gary Reynolds
Background • April 2010 Western Australia detected increase in spontaneous reporting of febrile convulsions, single brand? • Estimated 1/110 within 4-6 hours in ≤ 5 year olds • April 2010 NZ no signals from CARM • 24th April total of 4 reports • Rapid analysis of ED and admission data for Ak region children hospitals (1.5 million) • No more FC than normally expected (~25 each per week)
Actions taken Australia April 23rd New Zealand April 26th Recommendation not to give Fluvax brand to under 5s as precaution Stocks of Fluvax exhausted anyway • Influenza programme for children under five years suspended • Insufficient data on other brands to support their continued use Collaboration between Australian NCIRS, sanofipasteur and IMAC
Research • NZ in unique position to evaluate the safety of several brands of flu vaccine in young children • TIVs used for 2010: Vaxigrip, Fluvax, Influvac • All A/California/7/2009(H1N1),A/Perth/16/2009 (H3N2), B/Brisbane/60/2008 • (also one monovalent A/California/7/2009(H1N1): Celvapan) OBJECTIVES 1. Assess rate of febrile reactions following Vaxigrip and Fluvax in ≤ 5 years 2. Assess rate of febrile convulsion following Vaxigrip and Fluvax in ≤ 5 years 3. Assess reactogenicity of these vaccines in other age groups
Methodology • Primary care practices (practice nurses) identify consecutive vaccinees and run telephone questionnaire • Administer brief 6 (7) item survey • Vaccine identified by batch number • Three 2010 studies (total of 4142 doses) • 473 x 18 – 55 years (IMAC) • 100 x 6 years – 18 years (CSL) • 3569 x 6mos – 5 years (Sanofi)1 1. Petousis-Harris H, Poole T, Booy R, Turner N. Fever following administration of two inactivated influenza vaccines – A survey of parents of New Zealand infants and children 5 years and under. Vaccine.(2011) 29: 2933-2937.
Definitions • Fever either reported or measured • If measured then defined as ≥38°C • further defined into ≥38°C, ≥39°C and ≥40°C. • Major Febrile Events • Fever + ED/hospital visit • Fever + GI symptoms (vomiting) • Fever + musculoskeletal symptoms • Fever and malaise/lethargy • Fever and neurological symptoms • Rigors • Altered consciousness • Convulsive seizure • Defined as per Brighton Collaboration definitions Bonhoeffer J. Fever as an Adverse Event following Immunisation Case Definition and Guidelines of Data Collection, analysis and Presentation. Vaccine 2003:1 -6. Bonhoeffer J, Menkes J, Gold MS, de Souza-Brito G, Fisher MC, Halsey N, et al. Generalized convulsive seizure as an adverse event following immunization: case definition and guidelines for data collection, analysis, and presentation. Vaccine 2004;22(5-6):557-62.
Verification of cases • Clinical records obtained and/or further information sought via clinician interview for following: • Sought medical attention • Reported any neurological symptoms
Recall bias • Ability of parents to recall events as time between vaccination and survey increased • Logistic regression • Outcome • fever recalled within 24 hours or not • Explanatory variables • Lag time from vaccination to survey • Vaccine • Age and age squared in months • Summer/winter (May-Oct, Nov-Apr)
Results - recruitment There were 3188 children and 2244 parents/caregivers in our sample providing data for 3569 doses of vaccine. There was an average of 1.1 doses given per child.
Major febrile events occurring in Vaxigrip® and Fluvax® recipients *Witnessed loss of consciousness and tonic/clonic seizure.
Comparison of febrile events in children ≤5 years following 3559 doses of 2010 flu vaccine Celvapan, 10 doses, 2 medical advice, one fever and vomiting and one fever. 3 fevers within 24 hours
Youth aged 10 – 17 years • Active surveillance (post vaccine diary) • 69 diaries post Fluvax. 1/69 fever of 38.2°C
Adults aged 18 – 70 years • Active surveillance (post vaccine diary) • 156 diaries. No fevers • Local reactions
Ethnicity a risk for feverChildren 6/12 – under 6 years N=329 Male/Female 19%/26%
Conclusions • Febrile convulsions high following a single brand of flu vaccine 13-38 per 10,000 doses Cf with: wDTP vaccine 6-9 per 100,000 MMR 25-34 per 100,000 • UK enhanced passive surveillance found 2/10,000 and 1.4/10,000 following H1N1 • No excess in reporting • Not all brands/years equivalent • Further attention and resources to support programme design and planning and to maintain public confidence.