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hpr3822 :: A tale of wonder, angst and woe

Dissecting a COVID watch issued by Hong Kong Department of Health

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Hosted by Bookewyrmm on 2023-03-28 is flagged as Clean and is released under a CC-BY-SA license.
device discovery, curiosity. 2.

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Duration: 00:08:46


In December of 2022, I traveled to Hong Kong, at some point en-route or in-country, I contracted covid.

Backing up a step in preparation for the trip I was required to have a negative PCR before I could board the plane from the US as well as proof of vaccination and at least one booster shot.

HKSAR Department of Health - Health Declaration Form (

Upon arrival, I was required to quarantine for 3 days as well as take a home test (referred to as RAT: Rapid Antigen Test, by the locals) every day for the first 7 days

On the 2nd full day in HK, I was required to take another clinical PCR provided at a health center, free of charge.

On the third day I received my PCR and RAT tests as Covid Positive.

By law I was now required to quarantine in my hotel until I tested negative on 2 consecutive days. Since my symptoms were very mild, a sniffle and low grade temp, merely 2-3 deg above normal, I could stay in the hotel and was not required to transfer to a public health center.

I was also required to register the positive results with a government website. This registration kicked off a series of events, including a visit from a health representative. (he stood in the hall, I was not permitted to leave the room) I was Required to install an app on my phone called "Stay Home Safe'' and to wear a wristband that I presume was a GPS and possibly temp/pulse tracking device that connected to my phone by bluetooth. The agent installed the app, and synced the watch to it.

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Comment #1 posted on 2023-03-31 22:47:45 by Windigo

Wrist device

I've worked with some GPS tracking hardware, and they're usually much bulkier and require much larger batteries than a 2050 cell. If I had to guess, I would say your wrist device had one purpose: to make sure your wrist was inside it. Your phone app probably took care of any and all tracking required. That wrist device simply detected when you cut through that copper band, breaking the circuit, and alerted your phone via bluetooth. Your phone has all of the requisite tracking hardware, but it's not physically connected to you. Leave it behind, and you'd be out of quarantine! ...But not if they had a device attached to your body, which could detect if it's band had been disconnected.
Comment #2 posted on 2023-04-17 15:54:25 by Bookewyrmm

small update

A coworker found this link to an article explaining the functionality of the watch.

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