Faster than PCR and more accurate than lateral flow tests, the latest weapons against Covid-19 have four legs and a wet nose.
A study published on Monday found that people who are infected with coronavirus give off a distinct odour, which these highly trained dogs can detect with pinpoint precision.
Tala, a golden labrador in a red work jacket, greets me with a cursory sniff, before returning to his handler. I’m relieved to have passed the test, but feel a wet train of mucus on my hand where I petted him. This mucus fulfils an important purpose: dissolving odour molecules from the air and transporting them to olfactory receptors in the top of their nose, where the magic happens. Whereas humans have about 5m of these receptors, dogs have up to 300m.
Dr Claire Guest has always been fascinated by dogs, and humans’ relationship with them. After studying psychology, she worked for Hearing Dogs for Deaf People, where she met a woman who said her pet dalmatian had diagnosed a malignant melanoma on her calf. “She kept saying, ‘The dog sniffed it,’” Guest recalled. In 2002, Guest joined forces with an orthopaedic surgeon, John Church, to test whether dogs could be trained to distinguish between urine from healthy people and those with bladder cancer. The research, published in the BMJ, showed that they could.