As flu season returns and vaccines are rolled out, researchers at the Allen Institute are uncovering why vaccines don’t work as well in older adults—and what can be done to improve them.
Their findings may help create better vaccines for everyone, especially those over the age of 65.
In the largest study of its kind, published in the journal Nature, the scientists studied how immune cells, called T cells, change as we age.
T cells are important because they help the body recognize and fight viruses and help other cells make antibodies after vaccination.
The researchers discovered that these T cells go through big changes as people grow older. These changes happen even in healthy adults and are not simply caused by inflammation or chronic illness.
Claire Gustafson, a lead researcher at the Allen Institute, explained that this finding is surprising because it shows that aging itself—not inflammation—is behind the changes in the immune system. This helps explain why older adults often don’t respond as well to vaccines like the flu shot or COVID-19 boosters.
The study showed that memory T cells in older adults switch to what scientists call a “Th2-like” state. This is a change in how their genes behave, and it weakens the way T cells help other immune cells respond to vaccines. So, even if a vaccine includes the right virus particles, the body may still struggle to respond effectively.
These insights open the door to creating better vaccines. With this new understanding, doctors could use a person’s immune profile to predict how well they’ll respond to a vaccine. Vaccines could also be specially designed to work with the aging immune system.
For example, scientists may use new technologies—like CRISPR gene editing—to reprogram older T cells to act more like younger ones. This could improve how well older people respond to vaccines.
The research team worked with 96 healthy adults between the ages of 25 and 65 over two years. They collected data using advanced tools such as single-cell RNA sequencing and flow cytometry to look at each person’s immune system in great detail.
From this, they created a large online database called the Human Immune Health Atlas, which maps 71 different types of immune cells and shows how they change with age.
They then expanded their research to include over 16 million immune cells from people aged 25 to over 90. The result is the most detailed map of the aging immune system ever made—and it’s free for scientists around the world to use.
Jane Buckner from the Benaroya Research Institute said that this research was made possible thanks to the teamwork of researchers, doctors, and volunteers who shared their health information.
The study not only helps explain why aging affects vaccine performance, but it also offers hope for new treatments to keep the immune system strong as we age. It gives researchers around the world a powerful new tool to study how immune function changes over time and how to improve it.
As Gustafson noted, this is just the beginning. The data they collected will continue to help scientists learn more about how the human immune system works—and how to keep it healthier for longer.
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The study is published in Nature.
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