Sniffer dogs are a familiar sight at airports all over the world, where border agents use them to detect illegal substances and contraband.
Now some dogs are using their noses for a different purpose - coronavirus.
Dogs specially trained to detect Covid-19 have this week started sniffing passengers as part of a trial at Finland's Helsinki-Vantaa airport.
Volunteers are training a team of 15 dogs and 10 instructors for the research programme.
The dogs can detect coronavirus in humans five days before they develop symptoms, Anna Hielm-Bjorkman, the University of Helsinki professor who is running the trial, told Reuters news agency.
"They are very good [at detecting coronavirus]. We come close to 100% sensitivity," she said.
Passengers wipe their necks with cloths, which are then placed in a can and put in front of dogs to sniff. A canine test can deliver a result within minutes.
But while the trial has shown early promise, more research needs to be done to prove the efficiency of canine testing. At the moment, passengers who take part in the trial are also instructed to take a swab to confirm the result.
Vantaa Deputy Mayor Timo Aronkyto said it was possible that the dogs could in future "go around passengers in a similar way to customs dogs".