Dogs can be trained to detect up to 94 percent of Covid-19 infections – even in asymptomatic patients. This is based on UK research released over the weekend suggesting they could be used to screen passengers at airports and other entry points.
The study tested the known ability of dogs to act as biosensors that can detect odors related to human health – such as the presence of Plasmodium, which causes malaria – as well as drugs, explosives, and food.
Overall, the dogs were able to successfully identify between 82 and 94 percent of the samples of Sars-CoV-2, the virus that causes Covid-19.
Researchers at the London School of Hygiene and Tropical Medicine wanted to know if dogs can smell a characteristic odor caused by chemical compounds associated with someone who is Covid-19 positive but does not show symptoms.
They collected samples of clothing and face masks from people.
In one test, the socks of 200 Covid-19 cases were collected and placed in laboratory tests for six dogs that had been trained to indicate either the presence or absence of the chemical compound.
A dog trained to sniff Covid-19 examines a sweat sample at Chulalongkorn University in Bangkok © Reuters
The team at LSHTM, Medical Detection Dogs and Durham University said the study showed that Covid-19 infection “has a distinct odor that dogs can detect with incredible accuracy”.
“To the best of our knowledge, this study is the first that can assess in a randomized double-blind study in which the trainer and monitor were unaware of whether trained dogs can differentiate between the smell of Sars-CoV-2 infected and non-infected people.” The study group for each sample and with a sufficient number of dogs and individuals donating samples, ”the researchers wrote.
The dogs had to be trained not to identify “false positive” results in order to receive treats, even if there were no Covid-19 samples in a particular test.
The results have not yet been reviewed by experts.
On Friday, Thailand deployed dogs trained to detect coronavirus infections by sniffing samples of human sweat as the country grapples with a surge in infections, including many asymptomatic cases.
Three out of six trained Labrador Retrievers had shown a success rate of around 95 percent, similar to the UK study results.