https://www.vice.com/en_us/article/4aykpp/the-uks-covid-19-contact-tracing-app-is-a-mess-again

Just a few days after downloading “NHS Covid-19”—the UK government’s recently released contact-tracing app—Abbie received a notification informing them that they had potentially been exposed to the virus. But, when they actually went to open the notification, it simply disappeared. Abbie, who comes into contact with strangers daily through their job working in a restaurant, was spooked. 

“I have asthma, so I have been very vigilant and careful about social distancing and wearing my mask at all times at work. This notification struck panic into my heart,” Abbie, who asked we didn't use their last name, told Motherboard.