Dogs successfully trained to sniff out COVID could prevent the spread of the virus at airports and travel hubs

Man’s best friend has an amazing sense of smell. Dogs are respected olfactory connoisseurs, with up to 300 million olfactory receptors in their snouts (compared to a meager five to six million in humans) and 40 percent more brain space for analyzing smells. Fido can detect the slightest smell better than any artificial instrument. It’s a super canine ability that we’ve used to find missing people (call Lassie), locate illegal drugs and dangerous compounds like explosives, and catch smuggled contraband. And now we’re using it to eradicate COVID-19.

In a new study published Monday in the British Medical JournalA group of Finnish researchers found that dogs trained to sniff out the coronavirus can spot it with near 100 percent accuracy in airport travelers, raising hopes that our furry friends aren’t just catching COVID infections in crowded public spaces or at transport hubs – places with a higher risk of virus transmission – but also hospitals and even schools.

“This is a very important study showing that COVID-19 detection dogs can achieve greater than 90 percent accuracy and sensitivity, which is comparable to current testing methods but much faster,” said Kenneth Furton, a biochemist at Florida International University, which was not involved in the study but has previously investigated the use of dogs to detect COVID infection, The Daily Beast said in an email. “COVID-19 sniffer dogs provide results in seconds rather than minutes or hours, enabling large numbers of people to be screened without delay.”

The idea of ​​using smell to diagnose diseases dates back to ancient times. A human’s sense of smell alone isn’t strong enough – but a dog’s might be. Studies have shown that our four-legged friends can smell volatile organic compounds (VOCs), which are specific chemicals produced by the human body and end up in our blood, urine, faeces, skin or breath.

Dogs have been trained to recognize VOCs specific to diseases like epilepsy, cancer, diabetes and infections caused by pathogens like malaria. When the pandemic struck, scientists hypothesized that the dog’s sensitive nose would also be able to smell COVID. And that seemed to be the case – several preliminary studies from France, Britain, Germany and the United Arab Emirates found that people infected with the virus had a particular smell of sweat that the uninfected lacked and that dogs could detect .

In the new study, Finnish researchers took already-trained sniffer dogs and had them learn the smell of sweat from the coronavirus. The four dogs then had to sniff more than 420 skin swabs — a quarter from volunteers who tested positive for COVID and the rest from those who tested negative. The results were impressive: The trained sniffers had a combined diagnostic accuracy of 92 percent in detecting which samples were infected and which were not.

The dog noses were then used again, this time when screening passengers at Finland’s Helsinki-Vantaa International Airport. During an approximately four-month pilot program in fall 2020, the dogs’ sniff tests were compared to 303 COVID-PCRs from inbound travelers. All 296 swabs identified as negative by PCR testing were also identified as negative by the dogs, meaning their accuracy was nearly 98 percent. There were three positive cases that the dogs missed — one due to the alpha variant, which the dogs weren’t trained to smell.

There are still important questions that still need to be answered. For one, scientists still don’t know the specific VOCs associated with COVID. Another is what these results mean for populations with a high Prevalence of COVID-19 as there was not much of the virus among the airport passengers studied. The Finnish researchers estimate that in hypothetical high-prevalence scenarios, such as you might see in a hospital or assisted-living facility during the peak of an outbreak, the dogs still have a fairly high accuracy, with 88 percent for positive cases and almost 95 Percent for negative cases have cases. However, further studies with much larger datasets are needed to see if this is true.

There’s also the practicality of training large packs of COVID-19 detection dogs around the world and for different variants. For example, the dogs in the Finnish study could not detect a single positive case causing the alpha variant because they were used to the original coronavirus variant with no major mutations.

“We didn’t think dogs would distinguish different variants,” said Dr. Anna Hielm-Björkman, a veterinarian at the University of Helsinki and lead author of the study, told The Daily Beast in an email. “But with this information, we now know that even the smallest changes in pathogens require retraining with these new variants. This new information is crucial for the next epidemic. At the same time, there’s no need to worry because we know it’s quick and easy to retrain dogs that can already sniff out human diseases.”

Tracker dogs could still be a promising avenue for rapid, effective and potentially life-saving detection, especially if COVID is here to stay. In the US, Furton and colleagues from Florida International University ran two pilot programs testing COVID-19 sniffer dogs at Miami International Airport with promising results. Already trained dogs are being used in some schools in Massachusetts to detect COVID on surfaces. And some made their cute, albeit celebratory, appearance during a Miami Heat basketball game in February 2021. And while COVID-19 can spread to pets that are in close contact with humans, dogs appear largely safe from infection. Man’s best friend could become our best tool in the fight against COVID.