A new study points to the power of wearables to predict even presymptomatic infections, suggesting use one day against Covid-19

A new study that infected willing participants with common cold and flu viruses provides the most rigorous evidence yet that wearable health monitors could predict infections, even before a person starts experiencing symptoms. If the wearables can similarly predict infections in real-world conditions, the technology could add to existing disease surveillance and testing methods. But unresolved issues with standardizing wearables and testing them on diverse populations raise questions about their immediate utility. The new study, published Wednesday in JAMA Network Open, took aim at a research problem that has plagued other efforts to study wearables as infection detectors: small sample size. In two previous studies that looked at wearable devices like Apple Watches and Fitbits, tens of thousands of enrolled individuals corresponded to around 50 cases of Covid-19. In these studies and similar ones, it wasn’t clear when infected people first contracted the virus, further constraining the possibility of making predictions.