Newshub in New Zealand reported on March 9, 2020:
Scientists in Singapore may have found a clue as to how so many people aboard cruise ship the Diamond Princess ended up getting infected with COVID-19.
It appears the virus might be able to spread through air conditioning systems.
[...]
The third room however had samples taken before cleaning, and it tested positive. Thirteen out of 15 spots in the room had positive test results for the virus - including air outlet fans.
If true, this would appear to increase the risk in many public buildings.
Can COVID-19 be caught through air-conditioning systems?