The articles elaborate. In Japan and Singapore contract tracing is much easier,
Japan
> Less than two weeks later, she tested positive for the virus, and the authorities swiftly alerted others who had been at the club. As more infections soon emerged from three other music venues in the city, officials tested concertgoers and their close contacts, and urged others to stay home. All told, 106 cases were linked to the clubs, and nine people are still hospitalized.
Singapore
> Singapore's biggest cluster of Covid-19 patients, traced to a restaurant in Jurong, had more than just a dinner in common, said Ministry of Health director of medical services Kenneth Mak yesterday.
> "We've recognised that many of the individuals linked to this particular group of people getting infected had many common social activities," said Associate Professor Mak, pointing to other gatherings such as singing classes that infected individuals had taken part in together.
> "So, in fact, their social interactions went well beyond the dinner in that particular location, and as a result of those close activities... that's where the spread is actually occurring," he said.
Washington was at a choir, where everyone would have known each other
> Health officials said all 28 choir members who were tested for COVID-19 were found to be infected. The other 17 with symptoms never got tested, either because tests were not available or — like Comstock and Owen — the singers were under the impression that only people in dire condition were eligible.