A special type of blood test could give vital clues as to how an isolation hotel maintenance worker got Covid-19 from an infected guest he had never met.
Health officials are stumped and are being urged to use serology testing which can reveal if a person has had the disease even if they haven't had a positive Covid-19 test.
It could show if a third person is the missing link between the worker and the infected woman isolating in the hotel.
Charlotte Cook reports.