I quarantined in Beijing, Tokyo and Hong Kong. Here's what I learned.

About two weeks after I visited, Beijing authorities announced an outbreak linked to the wholesale market, marking the capital’s second coronavirus wave. Shortly after that time, high government officials also declared “wartime mode” to quash the outbreak.

Authorities used geo-spatial data from people’s mobile phones to send text messages to many who visited the market, asking them to quarantine. Restrictions varied, depending on the neighborhood and building.

The friend who was with me at the market even had a sensor attached to her front door that notified her building whenever she opened it.

I was required to quarantine for at least 14 days and get two Covid tests. My apartment management made sure I never left my room, not even to enter spaces like my building’s elevator or lobby.