The risk of fever following one dose of trivalent inactivated influenza vaccine in children aged ≥6 months to <36 months: a comparison of published and unpublished studies.
There are limited summary data published on the risk of fever and febrile seizures in children following influenza vaccination. We performed a review of the risk of fever and febrile seizures following receipt of trivalent inactivated influenza vaccine (TIV) in children aged ≥6 months to <36 months, searching PubMED and Google Scholar for English language articles from 2000 onwards, and initiated or ongoing unpublished studies since September 2007 using Clinicaltrials.gov. Exclusions included other vaccine co-administration, missing ages or participant numbers, or unmeasured fever. We reviewed articles and collated results using a standard data extraction template. We identified a total of 909 published papers and unpublished trials from a search conducted on 23 January 2013, 669 from Google Scholar, 114 from PubMed and 126 from the Clinicaltrials.gov online database. After excluding 890 published papers or unpublished trials, 5 published papers and 14 unpublished trials were included in this review. Extracted data on number of events, children at risk and time of follow-up were converted to the risk of fever, which was averaged per week of follow-up (referred to as 'averaged weekly risk'). Following one dose of TIV, the median averaged weekly risk of any fever (≥37.5°C) was 26.0% (range 10.3-70.0%) in unpublished trials compared to 8.2% (range 5.3-28.3%) in published papers (p=0.04). The median averaged weekly risk of severe fever (≥39.0°C) was 3.2% (range 0-10.0%) and 2.0% (range 0.6-17.0%), respectively (p=0.91). Variation in the reporting of fever by participant age groups, time since vaccination and the definition or measurement of fever resulted in a wide range of risk estimates. Reporting of febrile reactions should be standardised to allow comparison between manufacturers and influenza seasons.
Queensland Children's Medical Research Institute, The University of Queensland, and Children's Health Service, Queensland Health, Brisbane, Queensland, Australia; School of Population Health, The University of Queensland, Brisbane, Queensland, Australia; Epidemiology Unit, Victorian Infectious Diseases Reference Laboratory, Melbourne, Victoria, Australia. Electronic address: Marlena.kaczmarek@mh.org.au.
Marlena C
MC
Kaczmarek
Uyen T
UT
Duong
Robert S
RS
Ware
Stephen B
SB
Lambert
Heath A
HA
Kelly
D002675:Child, Preschool; D005334:Fever / Q000139:chemically induced* / Q000150:complications / Q000453:epidemiology*; D006801:Humans; D007223:Infant; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects*; D007251:Influenza, Human; D018570:Risk Assessment; D012640:Seizures / Q000139:chemically induced* / Q000453:epidemiology*; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000276:immunology
D007252:Influenza Vaccines; D015164:Vaccines, Inactivated
Adverse effects; Febrile; Fever; Influenza vaccines; Review; Seizures