A new cluster of Covid-19 cases in New Zealand prompted a widespread investigation to identify where they’re coming from. The New Zealand Herald reports: Nearly 90 new cases of Covid-19 have now been linked back to the new cluster, which itself stemmed from an “index case” — a 50-year-old man working at Mt Wellington’s Americold coolstore, with no history or link to overseas travel. Contact tracers have been trying to work backwards from that index case, who tested positive on August 11, in hopes of finding the “primary case” — or the person who brought the virus into the country in the first place. Friday — more than a week and 175,000 tests since the start of the outbreak — Prime Minister Jacinda Ardern shared some details on how exhaustive that process had been. Virtually all of the country’s border and managed isolation staff have been tested in the past 10 days, and so far there had been no additional cases, outside the mystery infection of a maintenance worker at Auckland’s Rydges hotel… University of Auckland microbiologist Associate Professor Siouxsie Wiles says it’s quite possible we’ll never get any further. “Is that a big deal? From the testing we’ve done so far, it looks like this is a pretty tight cluster — so I would say, no,” she said. “What we have lost is the opportunity to know how it happened, or what gaps need plugging. But at the same time, we have to remember that nothing is 100 per cent guaranteed to work all of the time.” Read more of this story at Slashdot.