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TGA presentation: 2016 Australasian Epidemiological Association (AEA) 23rd Annual Scientific Meeting, 15 September 2016

Presentation: Increased reports of allergic adverse events following 2015 influenza immunisation

29 September 2016

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Presentation

  • Presented by: Dr Paul Dutton, Signal Investigation Unit, Pharmacovigilance and Special Access Branch, Therapeutic Goods Administration
  • Presented at: 2016 Australasian Epidemiological Association (AEA) 23rd Annual Scientific Meeting
  • Presentation date: 15 September 2016
  • Presentation summary: This presentation describes a scientific research study undertaken by the TGA to investigate increased reports of allergic adverse events following influenza immunisation in 2015.

Transcript

Increased Reports of Allergic Adverse Events Following 2015 Influenza Immunisation

Dr Paul Dutton
MAE Scholar
Signal Investigation Unit, Pharmacovigilance and Special Access Branch
Medicines Regulation Division, TGA

2016 Australasian Epidemiological Association (AEA) 23rd Annual Scientific Meeting, 15 September 2016

Slide 1 - Background

  • Early in the 2015 influenza season, the Therapeutic Goods Administration (TGA) observed an increase in reports of allergic adverse events following influenza immunisation (AEFII) compared with previous years.
  • In the TGA Adverse Drug Reaction System (ADRS) database, allergic adverse events are included in a broader category known as Immune System Disorders (ISDs).
  • Initial evaluation of the reported cases suggested an increase in the number of ISD AEFII as a percentage of total AEFII from 13% in 2013 and 12% in 2014, to 21% in 2015.
  • This occurred in the context of:
    • two strain changes for the 2015 vaccine (Table 1 on next slide)
    • a month's delay in the commencement of the national influenza vaccination program.

Slide 2 - Background

Table 1: Composition of influenza virus vaccines for use in the southern hemisphere influenza season
Influenza virus vaccines
Trivalent vaccines Quadrivalent Vaccines
Year Vaccine virus 1 Vaccine virus 2 Vaccine virus 3 + Vaccine virus 4
2016 A/California/7/2009 (H1N1)pdm09-like virus A/Hong Kong/4801/2014 (H3N2)-like virus B/Brisbane/60/2008-like virus B/Phuket/3073/2013-like virus
2015 A/California/7/2009 (H1N1)pdm09-like virus A/Switzerland/9715293/2013 (H3N2)-like virus B/Phuket/3073/2013-like virus B/Brisbane/60/2008-like virus
2014 A/California/7/2009 (H1N1)pdm09-like virus A/Texas/50/2012 (H3N2)-like virus B/Massachusetts/2/2012-like virus B/Brisbane/60/2008-like virus *
2013 A/California/7/2009 (H1N1)pdm09-like virus A/Victoria/361/2011 (H3N2)-like virus B/Wisconsin/1/2010-like virus B/Brisbane/60/2008-like virus *
2012 A/California/7/2009 (H1N1)pdm09-like virus A/Perth/16/2009 (H3N2)-like virus B/Brisbane/60/2008-like virus  
2011 A/California/7/2009 (H1N1)-like virus A/Perth/16/2009 (H3N2)-like virus B/Brisbane/60/2008-like virus  

* Quadrivalent influenza vaccines were not marketed in Australia in 2013 and 2014

Slide 3 - Objectives

  • To investigate:
    • whether the increase persisted throughout the season and
    • whether any increase was related to a specific age group, sex, brand of vaccine, or jurisdiction.

Slide 4 - Methods

  • ISD AEFII data from cases reported to the TGA from 1 January 2011 to 31 December 2015 were downloaded into Excel from the TGA ADRS database.
  • Numbers and proportions were tabulated for five selected allergic AEFII:
    • anaphylaxis
    • angioedema
    • asthma/bronchospasm
    • urticaria
    • hypersensitivity*.
  • Total ISD AEFII data were also tabulated.

(All as a proportion of the total AEFII.)

(* includes; hypersensitivity, acute allergic reaction, allergy, allergy not otherwise specified, environmental allergy, systemic allergic reaction, and upper respiratory tract hypersensitivity reaction, site unspecified.)

Slide 5 - Methods

  • To consider young adults and women of child bearing age separately, ages were analysed in the following groups:
    • 0-4 years
    • 5-14 years
    • 15-44 years
    • 45-64 years
    • 65+ years.
  • Each group was also analysed by sex.
  • Odds ratios (OR) were calculated for the 2015 proportions compared with the average of the preceding four years.

Slide 6 - Results

  • The total number of case reports of AEFII for 2015 was 594*

    (*includes the small number of reports from quadrivalent vaccines, which were not available through the 2015 National Immunisation Program).

  • The percentage of ISD reports as a proportion of total AEFII:
    • at initial review in May 2015 this was 21%
    • at the end of 2015 the percentage had dropped to 18%
    • this remained significantly above the previous four year average of 12% (OR 1.55, 95%CI 1.21 – 1.99; p 0.001) (Figure 1 on next slide).

Slide 7 - Results

Figure 1: Number of Immune System Disorder adverse events (ISDs) and ISDs as a percentage of total AEFII, by year 2011-2015

Number of Immune System Disorder adverse events (ISDs) and ISDs as a percentage of total AEFII, by year 2011-2015

Table 1: Number of Immune System Disorder adverse events (ISDs) and ISDs as a percentage of total AEFII, by year 2011-2015
Year of vaccination Total Immune System Disorders
(n, %)
All adverse events following influenza vaccine
(n)
2015 104 (17.5) 594
2014 69 (12.2) 565
2013 74 (13.0) 570
2012 59 (13.5) 438
2011 53 (9.0) 587
2011-2014
Total (n, %)
Average (n)
255 (11.8)
63.8
2160
540

Slide 8 - Results

  • For total ISD cases as a proportion of total AEFII compared to the average of the previous 4 years, a significant increase was seen in:
    • males in the 5-14 year age group (n/N=6/22, OR 3.54, 95%CI 1.11-11.33; p 0.033) and in
    • females in the 45-64 year age group (n/N=35/157, OR 1.88, 95%CI 1.19-2.98; p 0.007)
    • but not in females in the child bearing age group (15-44 years) (n/N=27/140, OR 1.46, 95%CI 0.90-2.37; p 0.127).
  • No specific vaccine brand was identified as having disproportionally more adverse events in 2015.
  • About a month's delay was noted in the peak reporting of adverse events
    • consistent with the delay in the start of influenza vaccination through the National Immunisation Program.

Slide 9 - Results

  • Of the selected allergic AEFII analysed, statistically significant increases were seen in the proportions of anaphylaxis (OR 1.99, 95%CI 1.01 - 3.94; p 0.047) and hypersensitivity (OR 2.92, 95%CI 1.72 - 4.97; p <0.005) compared with the average of the previous four years.
  • The overall number of case reports of anaphylaxis and hypersensitivity were low (13 and 25 respectively).
  • The rate of anaphylaxis per 100,000 doses of influenza vaccine distributed was 0.2.
  • Anaphylaxis cases were reported by; Vic (6), WA (3), ACT (1), NT (1), SA (1) and unknown (1).
    • The relatively higher numbers reported from Victoria and Western Australia may be a result of enhanced ascertainment of cases in these states.

Slide 10 - Conclusions

  • No cause has been identified for the observed increase in the proportion of ISD AEFII:
    • there was no indication that particular vaccine brands were the cause
    • ISD adverse events were observed across vaccine brands, sex/age groups and jurisdictions
    • there were no abnormalities identified by the TGA batch release program and no clusters to indicate a possible batch problem
    • given the wide variation from year to year, the 2015 ISD AEFII levels may simply be at the high end of a natural variation.

Slide 11 - Conclusions

  • There has been no change to the risk/benefit of influenza vaccines in use in Australia to warrant regulatory or programmatic action.
  • Allergic AEFII have continued to be monitored during 2016
    • to date, the proportion of ISDs to the total AEFII is similar to the 2011-2014 average.

Slide 12 - Acknowledgements

  • Dr Bronwen Harvey MBBS BA MPH(Hons) GCHE FAFPHM, Director, Signal Investigation Unit, Pharmacovigilance and Special Access Branch, Therapeutic Goods Administration
  • Dr Stephanie Davis MBBS, M.App.Epid, FAFPHM, National Centre for Epidemiology and Population Health, Australian National University

Slide 13 - References

  1. WHO. Influenza: vaccines: WHO recommendations on the composition of influenza virus vaccines. 2016. World Health Organization. [2016; cited 2016 September 05];

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