HELSINKI (Reuters) — Dogs trained to detect the novel coronavirus began sniffing passenger samples at Finland’s Helsinki-Vantaa airport this week, authorities said, in a pilot project running alongside more usual testing at the airport.

The dogs’ efficiency has not been proven in comparative scientific studies so passengers who volunteer to be tested and are suspected as carrying the virus are instructed to also take a swab to confirm the result.

A team of 15 dogs and 10 instructors are being trained for the job in Finland by volunteers, sponsored by a private veterinary clinic. Among them is Kossi, a rescue dog from Spain, who was trained as a sniffer dog in Finland and who has worked before detecting cancers.

“What we’ve seen in our research is that the dogs will find (the disease) five days before they (patients) get any clinical symptoms,” Anna Hielm-Bjorkman, who is Adjunct Professor at the University of Helsinki and specialized in clinical research for companion animals, told Reuters.

“They are very good (at it). We come close to 100-percent sensitivity,” she said, referring to the dogs’ ability to detect cases of the virus.

In the canine test, a passenger swipes their neck with a gauze, places it in a can which is then handed over to another room for a dog to sniff and to deliver an immediate result.

A few months ago, authorities in the United Arab Emirates embarked on similar canine testing at Dubai International Airport using police dogs.

“In the future, it’s also possible… that these dogs go around passengers in a similar way to customs dogs,” Vantaa deputy mayor Timo Aronkyto, said.