The feature analyzes HRV, resting heart rate, and temperature to deliver a daily score on your body's readiness to fight off illness.
The smart ring startup behind the upcoming Circular Ring 2 has announced a new software feature designed to give users a proactive warning when their body is vulnerable to sickness.
Rolling out now via an app update to all Circular ring owners, the ‘Immunity Index’ works by analyzing a user’s key biometric signals each day, including heart rate variability (HRV), resting heart rate, sleep breathing regularity, and temperature stability.
By tracking subtle deviations from your baseline in these metrics—which are often the first physiological signs of your body fighting something off—the feature generates a simple, color-coded score on an 8-point scale. A score of 8/8 means your vitals are optimal, while a score of 2/8 or lower indicates your immunity may be compromised and that you should prioritize rest.
It’s similar to Oura’s Symptom Radar, which first debuted early last year before rolling out in full in December.
However, the key difference of Circular’s Immunity Index (at least from what we know without testing it in regular life) is that it’s a daily score, rather than Oura’s feature, which will only flare up if it spots a specific biometric pattern emerging.
Which approach works better in day-to-day use? We’ll let you know once we’ve tested Circular’s interpretation. However, we’re intrigued by this hyper-focused nature of this one; it’s effectively a readiness score for illness biomarkers.
Catching up with the competition
And it shows Circular is going in the right direction, with a continued focus on proactive health software that builds on the solid hardware package we saw when we went hands-on with the Circular Ring 2 at CES earlier this year.
The upcoming second-generation smart ring—which will begin shipping before the end of September, the company says—features eight-day battery life, and, crucially, ECG and FDA-cleared AFib detection.
But, as we say, while the hardware is essential, it’s genuinely helpful features like Immunity Index that can create a compelling reason for users to choose one ecosystem over another—especially with rivals like the Oura Ring 4 and Samsung Galaxy Ring vying for customers’ fingers.
