The government's chief information officer, Victor Lam, unveiled the e-tag at a press briefing this afternoon, saying that any Hong Kong residents who have been to Hubei in the past 14 days must undergo home quarantine of 14 days, a measure the new electronic bracelets are meant to ensure.

The tag is paired to a person's smartphone — using Bluetooth Low Energy, or BLE, technology — and is plugged into the mains at the wearer's home.

If the person wearing the tag unplugs the phone and leaves the quarantine zone with it, or if the distance between the tag and the phone exceeds 20 meters, an alert will be sent to the Department of Health and the police.

The authorities will also get an alert if the tag is broken or removed. Anyone who violates the home quarantine order faces up to six months in jail and a fine of HK$5,000 (US$644).