Attentive readers might have noticed my absence over the last couple of weeks. I’ve been trying to recover from a bout of illness.

It got me thinking about the immune system, and how little I know about my own immune health. The vast array of cells, proteins, and biomolecules that works to defend us from disease is mind-bogglingly complicated. Immunologists are still getting to grips with how it all works.

Those of us who aren’t immunologists are even more in the dark. I had my flu jab last week and have no idea how my immune system responded. Will it protect me from the flu virus this winter? Is it “stressed” from whatever other bugs it has encountered in the last few months? And since my husband had his shot at the same time, I can’t help wondering how our responses will compare. 

So I was intrigued to hear about a new test that is being developed to measure immune health. One that even gives you a score.

Writer David Ewing Duncan hoped that the test would reveal more about his health than any other he’d ever taken. He described the experience in a piece published jointly by MIT Technology Review and Aventine.

The test David took was developed by John Tsang at Yale University and his colleagues. The team wanted to work out a way of measuring how healthy a person’s immune system might be.

It’s a difficult thing to do, for several reasons. First, there’s the definition of “healthy.” I find it’s a loose concept that becomes more complicated the more you think about it. Yes, we all have a general sense of what it means to be in good health. But is it just the absence of disease? Is it about resilience? Does it have something to do with withstanding the impact of aging?

Tsang and his colleagues wanted to measure “deviation from health.” They looked at blood samples from 228 people who had immune diseases that were caused by single-gene mutations, as well as 42 other people who were free from disease. All those individuals could be considered along a health spectrum.

Another major challenge lies in trying to capture the complexity of the immune system, which involves hundreds of proteins and cells interacting in various ways. (Side note: Last year, MIT Technology Review recognized Ang Cui at Harvard University as one of our Innovators under 35 for her attempts to make sense of it all using machine learning. She created the Immune Dictionary to describe how hundreds of proteins affect immune cells—something she likens to a “periodic table” for the immune system.)

Tsang and his colleagues tackled this by running a series of tests on those blood samples. The vast scope of these tests is what sets them apart from the blood tests you might get during a visit to the doctor. The team looked at how genes were expressed by cells in the blood. They measured a range of immune cells and more than 1,300 proteins.

The team members used machine learning to find correlations between these measurements and health, allowing them to create an immune health score for each of the volunteers. They call it the immune health metric, or IHM.

When they used this approach to find the immune scores of people who had already volunteered in other studies, they found that the IHM seemed to align with other measures of health, such as how people respond to diseases, treatments, and vaccines. The study was published in the journal Nature Medicine last year.

The researchers behind it hope that a test like this could one day help identify people who are at risk of cancer and other diseases, or explain why some people respond differently to treatments or immunizations.

But the test isn’t ready for clinical use. If, like me, you’re finding yourself curious to know your own IHM, you’ll just have to wait.

This article first appeared in The Checkup, MIT Technology Review’s weekly biotech newsletter. To receive it in your inbox every Thursday, and read articles like this first, sign up here.