Table 1. Selected wearable initiatives on symptom screening and tracking, as well as contact tracing related to COVID-19.

Method type	Data sources	Platforms	Initiatives	Performance
Screen & track	RHR, sleep times, step count	Consumer-grade wearables & activity trackers	RKI Corona Datenspende, Scripps DETECT,13 Stanford Smartwatch Study10	RHR and step count patterns confirm physician office influenza reports; 80% patient detection rate for sensor and symptom reporting; sensor data provides indicators before symptom reports.
Screen & track	Cough, heart & respiratory rate (accelerometer), body temperature	Custom stretchable patch	Jeong et al.,6	Cough-related motion, heart beat (seismocardiogram), and respiration rate observable in the data.
Tracing	BT	Smartphones, BT beacons	Liu et al.,7 Montanari et al.,11 Bian et al.3	Smartphone-based proximity estimation unreliable in <2m range.
Tracing	Oscillating magnetic field	Custom belt-attached wearable	Bian et al.3	Highly localised proximity estimation up to 2.5 m.
Tracing	Ultra wideband positioning	Bracelet and base stations	www.kpdistance.com	Proximity accuracy down to 0.1 m.
Tracing	BT combined with sound fingerprints	Smartphones	Thiel et al.16 and unpublished work	Up to 20% accuracy increase on social distance detection wrt. BT.
Tracing	Near ultrasound	Smartphones	https://www.novid.org	Sub-meter accuracy.