Publications

Published: February 2010

Seasonal flu vaccine - summary of spontaneous reporting in New Zealand

Prescriber Update 31(1): 3
February 2010

With the advent of the pandemic flu last year, there has been considerable interest in this year's seasonal flu vaccine. The following is an overview of all the adverse events following immunisation (AEFIs) reported to CARM associated with the seasonal flu vaccine in previous years (whether or not they have been considered by CARM to be causally related).

In the last decade, CARM has received between 91 and 135 reports per year where the seasonal flu vaccine has been suspected by the reporter to have caused an adverse event. These AEFIs can be grouped into various categories to give an overview of the reporting profile. The profile for seasonal flu vaccine is shown in Table 2 below. The table includes all 1509 reports received by CARM since the start of the adverse reactions reporting scheme in New Zealand in 1965 through to the end of September 2009.

Table 2: Profile of reported AEFI by category

Category# Total number of events*
Alimentary 246
Application site 860
Cardiovascular 244
Endocrine/Metabolic 12
Haematological 26
Liver 5
Musculoskeletal 210
Nervous System 515
Other 432
Procedure Related 1
Psychiatric Changes 188
Resistance Mechanism Disorders 14
Respiratory 186
Skin & appendages 326
Special Senses 83
Urinary 3
Total 3351

# CARM classification.

* The number of events is greater than the number of reports as one report may include one or more suspected reactions.

Over the last five years the reporting for most of the categories as a proportion of total reports for that year has been similar. The exceptions are a higher proportion of reports of dizziness in the cardiovascular category in 2006 and of injection site inflammation and pain in 2005 and 2007.

Table 3: The ten most commonly reported AEFIs for seasonal flu vaccine

Adverse event Number Category
Injection site inflammation 456 Application site
Injection site pain 214 Application site
Headache 149 Nervous system
Dizziness 122 Cardiovascular
Fever 118 Nervous system
Myalgia 97 Musculoskeletal
Nausea 95 Alimentary
Urticaria 77 Skin and appendages
Pruritus 71 Skin and appendages
Injection site erythema 66 Application site


There have been previous concerns that immunisation with influenza vaccine may cause rare neurological or immunological effects such as Guillain-Barré syndrome, facial/Bell's palsy or convulsions. Epidemiological studies have not consistently found an association between these types of events and seasonal flu vaccines.1,2 Since 1965 CARM has received 14 reports of Guillain-Barré syndrome, 7 reports of facial palsy, 3 reports of Bells palsy, 5 reports of transverse myelitis and 11 reports of convulsions. The reporting rate for all of these events is lower than the background rate in the general population.3

A review of the reported AEFI by CARM and Medsafe has not altered the benefit risk balance for these vaccines which continues to be favourable.

Healthcare professionals are encouraged to continue to report suspected adverse reactions to all vaccines and medicines to CARM.

References
  1. Haber P, Sejvar j, Mikaeloff et al. 2009. Vaccine and Guillain-Barré Syndrome Drug Safety 32: 309-323.
  2. Stowe J, Andrews N, Wise L et al. 2006. Bell's palsy and parenteral inactivated influenza vaccine. Hum Vaccin 2: 110-2
  3. Black S, Eskola J, Siegrist CA et al. 2009. Importance of background rates of disease in assessment of vaccine safety during mass immunisation with pandemic H1N1 influenza vaccines. Lancet 374: 2115-22