Fever following administration of two inactivated influenza vaccines—A survey of parents of New Zealand infants and children 5 years of age and under

Due to a dramatic increase in reported febrile convulsions in Western Australia following a routine pediatric influenza vaccination programme we evaluated parental recall of fever in their child following 2010 trivalent influenza vaccine manufactured by either Sanofi Pasteur (Vaxigrip®) or CSL Biotherapies (Fluvax®) to determine if the rates of febrile events in infants and children 5 years and under following administration of either Vaxigrip® or Fluvax® were significantly different.MethodA convenience sample of New Zealand General practices who had received stocks of the vaccines of interest consecutively contacted parents of infants and children under 5 years of age who received at least one dose of 2010 influenza vaccine. A brief questionnaire was administered with the main outcome parental recall of fever within 24 h of vaccination.ResultsResponse rate was 99%. There were 327 parents of children aged 6 months to 5 years attending one of 23 primary care practices who had received a dose of either the Vaxigrip® or Fluvax® vaccine between 4th March and 28th June 2010 surveyed. A total of 422 doses were given of which 267 were Vaxigrip®, 133 were Fluvax® and 22 another vaccine. Fever occurred significantly more frequently within 24 h following administration of Fluvax® compared with Vaxigrip® RR 4.33 (2.44–7.70). When fevers were measured they were, on average, higher in the Fluvax® vaccines (38 °C compared with 39 °C). Additionally, recipients were more likely to seek medical advice for fever following Fluvax® RR 23.11 (2.96–180.12).ConclusionsThere is considerable variation in reactogenicity between two 2010 seasonal vaccines in infants and young children. Vaxigrip® is significantly less reactogenic when compared to Fluvax® in this population in which Fluvax® is associated with unacceptably high rates of febrile reactions. There has been insufficient safety evaluation of seasonal influenza vaccine safety in this population.