Published: 7 March 2019


Influenza vaccine: Healthcare worker vaccination, and adverse reaction reports 2018

Prescriber Update 40(1): 16–18
March 2019

Key Messages

  • One out of four New Zealanders is infected with influenza each year, and around 80 percent of those infected are asymptomatic but still contagious.
  • The Ministry of Health’s goal is for 80 percent of all healthcare workers to be immunised annually against influenza.
  • The most commonly reported suspected adverse reactions to influenza vaccine in 2018 were injection site inflammation, arm pain, nausea, headache and pruritus.
  • Nurses submitted the majority of influenza vaccine adverse reaction reports in 2018, followed by GPs and pharmacists.

Influenza is a significant public health issue in New Zealand, with up to a quarter of the population infected each year.

Annual influenza vaccination of healthcare workers

Healthcare workers are at increased risk of exposure to influenza1 and may transmit infection without knowing they are infected2. A recent serosurvey showed that 1 out of 4 New Zealanders is infected with influenza each year, and that around 80 percent of those infected are asymptomatic3. An asymptomatic carrier can unknowingly expose their family, co-workers and patients to the influenza virus.

In 2018, the Ministry of Health introduced a goal of 80 percent of all healthcare workers to be immunised annually against influenza2. Achieving influenza immunisation coverage of 80 percent of the population is sufficient to establish herd immunity against most influenza viruses4. Annual influenza vaccination of healthcare workers is likely to reduce illness among the patients they care for1,5,6.

National district health board (DHB) healthcare worker influenza coverage in 2018 was 68 percent, with individual DHBs ranging from 57 percent to 88 percent7. (Note that this coverage figure only includes healthcare workers employed by DHBs.)

Influenza vaccine adverse reaction reports

Quadrivalent influenza vaccines were funded for the first time in 2018 (Influvac Tetra for individuals aged 3 years and older; Fluarix Tetra for children aged under 3 years). The vaccines contained two influenza A strains and two influenza B strains.

The Centre for Adverse Reactions Monitoring (CARM) received 232 reports of adverse reactions to influenza vaccine in 2018 (Table 1); as expected, based on the higher usage, the majority (73%) were associated with Influvac Tetra. There were a total of 582 suspected adverse reactions to the vaccines described in these reports.

Table 1: Number of reports of adverse events following influenza vaccination received by CARM and number of influenza vaccine doses distributed, 2013–2018

  2013 2014 2015 2016 2017 2018
Number of adverse event reports following influenza vaccination 290 253 241 212 191 232
Influenza vaccine doses distributeda 1,253,600 1,206,573 1,211,152 1,245,934 1,217,169b 1,317,197
Estimated reporting rate per 100,000 doses 23.1 21.0 19.9 17.0 15.7 17.6
  1. The number of doses distributed is not equal to the number of people who received the vaccine.
  2. The 2017 influenza vaccine distribution figures were updated in 2018 and differ slightly from those previously published in Prescriber Update ( The estimated reporting rate is unchanged.

The most commonly reported suspected adverse reactions were injection site inflammation, arm pain, nausea, headache and pruritus (Table 2).

Table 2: Top five reported suspected adverse reactions for the seasonal influenza vaccines, 2018

Adverse reaction Number Percentage of total reactions
Percentage of total reports
Injection site inflammation 42 7.2 18.1
Arm pain 23 3.9 9.9
Nausea 23 3.9 9.9
Headache 21 3.6 9.1
Pruritus 19 3.3 8.2

Six of the influenza vaccine-related reports were considered serious. A serious adverse event is determined by CARM according to internationally agreed criteria (ie, results in death or is life-threatening, causes or prolongs hospitalisation, results in persistent or significant disability/incapacity or is a congenital abnormality).

One death with a temporal association to the 2018 influenza vaccine was reported to CARM. A patient with a history of severe coronary artery disease and underlying flu-like illness was reported to have died after receiving influenza and zoster vaccines. The death was considered to be due to cardiac arrest and the patient’s associated background history, and not related to the vaccines.

The majority of reports in 2018 were submitted by nurses (72.4%), followed by GPs (16.8%) and pharmacists (3.9%). This reporter pattern is similar to previous years.

  1. Dolan G, Harris R, Clarkson M, et al. 2013. Vaccination of healthcare workers to protect patients at increased risk of acute respiratory disease: summary of a systematic review. Influenza and Other Respiratory Viruses 7(Suppl 2): 93-6. URL: (accessed 18 January 2019).
  2. Ministry of Health. 2018. Ministry of Health position statement: addressing influenza immunisation of healthcare workers March 2018. URL: (accessed 10 January 2019).
  3. Huang S (on behalf of the SHIVERS investigation team). 2016. Key findings – SHIVERS. Presented at the 2016 New Zealand Influenza Symposium, 2 November 2016 (updated January 2017). URL: (accessed 14 January 2019).
  4. Plans-Rubió P. 2012. The vaccination coverage required to establish herd immunity against influenza viruses. Preventive Medicine 55(1): 72–7. DOI: 10.1016/j.ypmed.2012.02.015 (accessed 14 January 2019).
  5. Ahmed F, Lindley M, Allred N, et al. 2014. Effect of influenza vaccination of healthcare personnel on morbidity and mortality among patients: systematic review and grading of evidence. Clinical Infectious Diseases 58(1): 50–7. DOI: 10.1093/cid/cit580 (accessed 14 January 2019).
  6. Riphagen-Dalhuisen J, Burgerhof J, Frijstein G, et al. 2013. Hospital-based cluster randomised controlled trial to assess effects of a multi-faceted programme on influenza vaccine coverage among hospital healthcare workers and nosocomial influenza in the Netherlands, 2009 to 2011. Eurosurveillance 18(26): pii=20512. URL: (accessed 18 January 2019).
  7. Ministry of Health. 2018. 2018 DHB Health Care Worker Influenza Immunisation Coverage December 2018. URL: (accessed 10 January 2019).
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