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Adverse events following vaccination of older people may be under-reported

Hazel J Clothier, Nigel W Crawford, Melissa Russell and Jim P Buttery
Med J Aust 2017; 207 (7): 301-302. || doi: 10.5694/mja16.01371
Published online: 2 October 2017

Adverse events following immunisation (AEFIs) in Australia are monitored by diverse jurisdictional passive surveillance systems that report to the national database, established primarily for detecting safety problems with childhood vaccinations. Supplementary, active AEFI surveillance systems, such as AusVaxSafety (operated by the National Centre for Immunisation Research and Surveillance) request AEFI information by automated SMS and email messages after selected vaccinations. Understanding AEFI reporting patterns for older people is important for identifying safety problems in this group, particularly following the introduction of a zoster vaccine program targeting 70–79-year-old people in November 2016.1

During July 2007 – June 2016, the Victorian enhanced passive AEFI surveillance service, Surveillance of Adverse Events Following Vaccination In the Community (SAEFVIC),2 received 645 reports for people aged 60 or more (6.5% of all reports), a mean of 72 reports per year; 69% concerned women, and pneumococcal or influenza vaccines were the most frequently implicated vaccines (697 of 794 [88%]). The most frequent AEFIs were localised reactions (40.6% of all reactions; 95% confidence interval [CI], 37.6–43.6%); serious AEFIs were reported in 11% of cases (95% CI, 8.7–14%), and 5.4% of reported patients (95% CI, 3.8–7.5%) were hospitalised. Increasing age was not associated with higher frequencies of serious AEFIs or seeking medical attention (Box).

Two deaths were reported, unlikely to have been vaccine-related: a single vehicle accident after an uneventful influenza vaccination, and a post-vaccination diagnosis of acute disseminated encephalomyelitis. As a result of high annual influenza vaccination coverage in this population, coupled with age-related baseline mortality rates, deaths coincident with vaccination are likely to be more frequent in older people; robust investigation and causality assessment are therefore critical.3

Given that each year an estimated 75% of Australians aged 65 or more receive influenza vaccine, and many also receive pneumococcal vaccine, AEFI reporting for older people was less frequent than anticipated. In 2013, fewer AEFIs per influenza vaccine dose were reported for Australians over 65 than for those aged 18–65 years.4 Despite having more comorbidities, older Australians also reported fewer serious AEFIs in an earlier study of all age groups.5 The apparent under-reporting may reflect adverse events being perceived as normal in older people and therefore not linked with recent vaccinations, a higher threshold for reporting, or reduced access to reporting channels.

Analysing hospital admissions may increase case ascertainment, particularly for serious AEFIs. The expansion of AusVaxSafety in 2017 to include all age groups may also increase reporting by prompting associating events with recent vaccination,6 but surveillance via mobile phone messaging in this age group may be unreliable.

Other methods of detection may be needed for AEFIs in older people. Improving case ascertainment and using vaccination data from the Australian Immunisation Register, which has recorded vaccinations for all age groups since 2016, will enable more sensitive and reliable surveillance, maintaining the overall safety of the National Immunisation Program.

As new vaccine programs are introduced for older people, vaccine pharmacovigilance in this age group must be improved. AusVaxSafety active surveillance is an important first step.

Box – Adverse events following immunisation (AEFIs) reported to SAEFVIC, July 2007 – June 2016, by age group

 

Age at vaccination


Total

60–69 years

70–79 years

80–89 years

≥ 90 years


AEFI reports

345

244

51

5

645

Sex (women)

252 (73%)*

158 (65%)

33 (65%)

4 (80%)

447 (69%)

Reactions

 

 

 

 

 

 Localised

240 (70%)

169 (69%)

27 (53%)

3 (60%)

439 (68%)

 Systemic

66 (19%)

28 (11%)

9 (18%)

1 (20%)

104 (16%)

 Fever

53 (15%)

28 (11%)

6 (12%)

0

87 (13%)

 Gastrointestinal

50 (14%)

31 (13%)

5 (10%)

0

86 (13%)

 Musculoskeletal

41 (12%)

33 (14%)

1 (2%)

2 (40%)

76 (12%)

 Allergic

28 (8%)

30 (12%)

2 (4%)

1 (20%)

61 (9%)

 Headache

30 (9%)

15 (6%)

1 (2%)

0

46 (7%)

 Inflammatory/immune

21 (6%)

8 (3%)

1 (2%)

1 (20%)

31 (5%)

 Respiratory

14 (4%)

3 (1%)

3 (6%)

1 (20%)

21 (3%)

 Cardiac

9 (3%)

7 (3%)

0

0

16 (2%)

 Neurological

8 (2%)

4 (2%)

1 (2%)

0

13 (2%)

 Other§

54 (16%)

36 (15%)

13 (25%)

1 (20%)

104 (16%)

 Total

614

386

74

8

1082

Serious AEFIs, number

38

28

5

0

71

 Proportion (95% CI)

11.0%
(7.9–15%)

11.5%
(7.7–16%)

9.8%
(3.2–21%)

 

11.0%
(8.7–14%)

Visited emergency department

18

16

0

0

34

 Proportion (95% CI)

5.2%
(3.1–8.1%)

6.6%
(3.8–10%)

5.3%
(3.8–7.3%)

Admitted to hospital, number

14

18

3

0

35

 Proportion (95% CI)

4.1%
(2.2–6.7%)

7.4%
(4.4–11%)

5.9%
(1.2–16%)

5.4%
(3.8–7.5%)

Attended clinic, number

12

5

0

0

17

 Proportion (95% CI)

3.5%
(1.8–6.0%)

2.0%
(0.7–4.7%)

2.6%
(1.5–4.2%)

Vaccines

 

 

 

 

 

 Influenza

210 (61%)

121

31 (61%)

3 (60%)

365 (57%)

 Pneumococcal

166 (48%)

145

18 (35%)

3 (60%)

332 (51%)

 Diphtheria/tetanus/pertussis booster

45 (13%)

21

3 (6%)

0

69 (11%)

 Zoster

0

0

1 (2%)

0

1 (2%)

 Other

16 (5%)

10

1 (2%)

0

27 (4%)

 Total

437

297

54

6

794


SAEFVIC = Surveillance of Adverse Events Following Vaccination In the Community. * In one case, sex was not reported. † Multiple responses possible. ‡ Includes lethargy and malaise. § Includes drug administration errors (21 cases).

Received 30 November 2016, accepted 5 April 2017

  • Hazel J Clothier1,2
  • Nigel W Crawford1,2
  • Melissa Russell2
  • Jim P Buttery1,3,4

  • 1 SAEFVIC, Murdoch Children's Research Institute, Melbourne, VIC
  • 2 University of Melbourne, Melbourne, VIC
  • 3 Monash Children's Hospital, Melbourne, VIC
  • 4 Monash Centre for Health Research and Implementation, Monash University, Melbourne, VIC


Acknowledgements: 

We thank the immunisation nurses and staff of SAEFVIC who receive and review the AEFI reports, and Heath Kelly for his editorial guidance. SAEFVIC is funded by the Department of Health and Human Services, Victoria. Hazel Clothier receives an Australian Government Research Training Program Scholarship.

Competing interests:

No relevant disclosures.

  • 1. National Centre for Immunisation Research & Surveillance. Zoster vaccine for Australian adults: information for immunisation providers [factsheet]. Oct 2016. http://www.ncirs.edu.au/assets/provider_resources/fact-sheets/zoster-vaccine-fact-sheet.pdf (accessed Jan 2017).
  • 2. Clothier HJ, Crawford NW, Kempe A, Buttery JP. Surveillance of adverse events following immunisation: the model of SAEFVIC, Victoria. Commun Dis Intell Q Rep 2011; 35: 294-298.
  • 3. Gold MS, Balakrishnan MR, Amarasinghe A, MacDonald NE. An approach to death as an adverse event following immunization. Vaccine 2016; 34: 212-217.
  • 4. Dey A, Wang H, Quinn HE, et al. Surveillance of adverse events following immunisation in Australia annual report, 2014. Commun Dis Intell Q Rep 2016; 40: E377-E390.
  • 5. Clothier HJ, Selvaraj G, Easton ML, et al. Consumer reporting of adverse events following immunization. Hum Vacc Immunother 2014; 10: 3726-3730.
  • 6. National Centre for Immunisation Research and Surveillance. AusVaxSafety [webpage]. Updated May 2017. http://www.ncirs.edu.au/vaccine-safety/ausvaxsafety/ (accessed July 2017).

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