Finnish researchers have done something new to combat the detection of COVID-19: they’ve hired four dogs to sniff it out. And it seems to be working with a near foolproof accuracy.

Anna Hielm-Björkman of the University of Helsinki, who is overseeing the trial, has noted that the dogs in the trial have had a near-100 percent accuracy rate when detecting COVID-19, even days before a person began displaying symptoms.

Dogs have proven to be surprisingly when trained to sniffing out other diseases, like malaria and breast or lung cancer across all stages of the disease. Dogs are even more accurate when it comes to detecting cancer in a blood sample, or in the breath of someone with lung cancer. No one is exactly sure why dogs are so adept at disease-sniffing, but it’s certainly a pleasant mystery t solve.

It’s a fairly simple process, conducted largely via human sweat and outlined in . International passengers arriving in Helsinki are asked to dab their skin with a wipe. Passengers place their swap into a beaker, which is taken to a different room containing different control scents. Then, the dogs do their thing.

Dogs generally indicate the presence of the COVID-19 virus by yelping, pawing, or laying down. The person whose sample is in question is then advised to take a nasal swap test to see if the dog is accurate. Generally, it seems like they are.

Officials conducting the experiment have noted that it’s a far more practical, time-sensitive, and cost-effective way to screen large volumes of people for a virus as opposed to testing everyone who comes into the country.

It’s important to note that this is still a test, but the results so far have been promising. If the trial proves to maintain this level of success, disease-sniffing dogs could prove a crucial asset when it comes to international travel and further reopening large gathering places.