Influenza is the greatest contributor to vaccine-preventable burden of disease in Australia, and annual vaccination is our best means for preventing influenza infection.

Typically, research into infectious disease among people who inject drugs (PWID) focuses on disease acquired through injection, like blood-borne viruses (e.g., HIV, hepatitis C) and bacterial infections that result in severe health outcomes (e.g., endocarditis, sepsis).

However, it is likely PWID are susceptible to severe health outcomes after infection with other diseases, like influenza. This is because there is a high prevalence of underlying health conditions among PWID, including chronic respiratory conditions and liver disease.

Additionally, PWID may be less likely to access influenza vaccination due to social determinants of health that are prevalent among this population, for example, low socioeconomic status, low levels of formal education, and homelessness.

However, this is an under-researched area and there is little data on influenza vaccine uptake among PWID. Understanding the characteristics of PWID who do get vaccinated, and the barriers to vaccination among PWID who do not get vaccinated, will help us better deliver interventions that increase vaccine uptake.

To address this knowledge gap, we used data from the Illicit Drug Report System (IDRS) surveys that took place from June to September 2020 to investigate uptake, barriers and correlates of influenza vaccination among PWID.

We found that PWID were less likely to be vaccinated than the general population

Approximately two-fifths of participants reported that they had been vaccinated in the past 12 months. However, influenza requires annual seasonal vaccination, and only one-quarter of participants had been vaccinated for the current influenza season. This is significantly lower than the general Australian population: a national survey that took place a month before our interviews began reported a seasonal vaccination rate of 56 per cent.

Participants who had not been vaccinated in the past year mostly reported barriers relating to motivation and low risk perception of disease

The belief that influenza does not carry serious risk is a key barrier cited in influenza vaccine hesitancy studies, and this was reflected in our sample. Vaccination against a disease considered to be low risk may be a low priority among PWID compared to more immediate concerns relating to substance use, food and housing for some people. This was reflected in the high proportion of participants reporting motivation-related barriers. Importantly, this low motivation may also be the result of broader shortcomings of the health system to address the specific needs of PWID, including lack of access to, and education about, vaccination, as well perceived stigma with identifying as someone who inject drugs.

We found that PWID who had accessed opioid agonist treatment (OAT) in the last six months were significantly more likely to have been vaccinated

This aligns with previous research that has shown OAT (e.g., methadone, buprenorphine) has health benefits beyond the treatment of opioid dependence, for instance increasing hepatitis C treatment adherence and preventing mortality from a variety of causes, including cancer, suicide, and drug and alcohol-related reasons. Higher vaccine uptake among people in OAT may be a result of their engagement with the healthcare system or may reflect concern about health more broadly.

How can we maximise influenza vaccine uptake among PWID?

Our research suggests we could increase uptake by facilitating convenient vaccine uptake at services PWID already intersect with, including needle and syringe programs, emergency departments, prisons, and OAT and other specialised health services for people who use drugs. This removes motivation-related barriers. To achieve optimal uptake, these interventions should also include education on the utility and safety of influenza vaccines.

What does this mean in the context of the COVID-19 pandemic?

Given the high prevalence of comorbid conditions among PWID, they should be prioritised for COVID-19 vaccination. Data from Melbourne IDRS surveys conducted in December 2020 suggest PWID may be more hesitant to receive the COVID-19 vaccination than the general population, with the main barrier being safety concerns. While this barrier differs to those identified for of the influenza vaccine, our study may provide important data that can be used to inform methods to increase COVID-19 vaccination among PWID. Ensuring convenient vaccine access at services PWID already intersect may provide the opportunity to increase awareness of the risk of COVID-19 infection and to provide information regarding vaccine safety and benefit.

Watch this space! The 2021 IDRS surveys are underway and data on COVID-19 vaccine acceptability, barriers and facilitators among PWID will be available soon. To find out more, subscribe to our monthly Drug Trends e-bulletin here.

For further information, see our journal article in Drug and Alcohol Dependence.

To request a copy of the paper, email:

The flu vaccine is available at most GPs and pharmacies. For more information on the flu vaccine and whether you qualify for free vaccination, see here.

Funding: The Illicit Drug Reporting System is funded by the Australian Government Department of Health under the Drug and Alcohol Program.