Studies probing the role of air conditioners in the spread of covid-19 suggest they are safe as long as the rooms have regular ventilation On 1 February, a passenger on the British cruise liner Diamond Princess, who had disembarked in Hong Kong seven days earlier, was found infected with covid-19.
Within days, the operator, Princess Cruises, cancelled the trip and docked on the Japanese coast. The passengers were asked to self-quarantine in their cabins, with Wi-Fi, meals and other facilities taken care of by the staff.
And yet, two weeks later, 542 of the 2,666 passengers tested positive for the virus. There are several theories about why the virus spread.