People with chronic health conditions like diabetes and heart disease can still build robust immunity from flu vaccines, according to new research from Australia. A study of over 300 Australian First Nations and non-Indigenous adults found that despite having more inflammation in their bodies before vaccination, individuals with long-term health conditions developed similar numbers of protective B cells and antibodies after receiving the flu shot as those without chronic illness.

Why Does This Matter for People With Chronic Conditions?

First Nations people globally face disproportionate risks from severe influenza infection during seasonal outbreaks and pandemics. At the same time, they experience significantly higher rates of chronic conditions including diabetes, kidney disease, and heart disease. Until now, researchers had little understanding of how these pre-existing health problems affect the immune system's ability to respond to flu vaccination.

The research team, led by scientists at the Doherty Institute in partnership with the Menzies School of Health Research in Darwin, recruited participants with and without long-term health conditions to measure their immune responses before and after flu vaccination. The findings, published in Nature Communications, offer reassuring evidence that vaccination remains an effective protection strategy for this vulnerable population.

What Did the Study Actually Find About Immune Responses?

Before vaccination, people with chronic health conditions showed measurable differences in their immune systems. They had more signs of inflammation circulating in their blood and immune cells that were more active compared to people without chronic conditions. This raised an important question: would their immune systems still respond effectively to the vaccine ?

The answer was encouraging. After vaccination, both groups developed more B cells and antibodies targeting the influenza virus. B cells are white blood cells that produce antibodies, which are proteins that recognize and fight off specific viruses. Crucially, these B cells can remember parts of the virus after vaccination and respond faster if someone encounters the flu later.

However, researchers did notice one difference. While people with chronic health conditions produced similar numbers of B cells as those without chronic illness, some of their B cells had different characteristics that were linked to inflammatory conditions. Despite this distinction, the overall immune protection remained strong.

How to Protect Yourself if You Have Chronic Health Conditions

• Get vaccinated annually: The study supports flu vaccination for all individuals with long-term health conditions, making it especially relevant for First Nations people globally who face higher rates of chronic disease and increased susceptibility to severe influenza.
• Discuss timing with your doctor: If you have diabetes, kidney disease, heart disease, or other chronic conditions, talk with your healthcare provider about the best time to receive your annual flu vaccine.
• Monitor for symptoms: Even vaccinated individuals can contract the flu, so remain alert for symptoms like fever, cough, and body aches, and seek medical care promptly if they develop.

"Our study supports influenza vaccination for individuals with long-term health conditions, which is especially relevant to First Nations people globally with a higher rate of long-term health conditions and increased susceptibility to influenza severity," stated Dr. Louise Rowntree, Group Leader in the Kedzierska Laboratory at the Doherty Institute.

Dr. Louise Rowntree, Group Leader in the Kedzierska Laboratory, Doherty Institute

The research involved collaboration across multiple institutions, including the University of New South Wales, the WHO Collaborating Centre for Reference and Research on Influenza, CQUniversity, and the Center for Influenza Disease and Emergence Response. Funding came from the National Health and Medical Research Council (NHMRC) and the National Institutes of Health (NIH) in the United States.

This study addresses a critical gap in immunology research. While scientists have long known that chronic inflammation can complicate immune function, understanding how it specifically affects vaccine responses in real-world populations has been limited. By examining both First Nations and non-Indigenous participants, the research provides insights relevant to diverse populations facing similar health challenges.

The findings come as influenza season is well underway in Australia, making the timing particularly relevant for public health messaging. For First Nations communities and others managing chronic health conditions, the message is clear: flu vaccination remains a valuable tool for protection, even when your body is already dealing with other health challenges.