As the coronavirus pandemic worsens and cases rise in separate parts of the world owing to fresh waves, a new detector has come around — sniffer dogs. A new study shows that sniffer dogs can be trained to identify people with the SARS-CoV2 virus by their odour.

Researchers at the London School of Tropical Medicine, who presented a new study, said that these dogs could soon be used at airports or mass gathering venues to pick up the “corona odour” of Covid-19 infected people. Working in teams of two, the Covid-trained dogs could screen a line of several hundred people coming off a plane within half an hour and detect with up to 94.3 per cent sensitivity those infected, Reuters reported.

The study involved 3,500 odour samples donated in the form of unwashed socks or T-shirts worn by the public and healthcare workers. Researchers said that the dogs were even able to sniff out asymptomatic or mild Covid-19 cases, as well as cases caused by a mutant variant that emerged in the UK. The samples of the socks were arranged in lab tests for six dogs that had been trained to indicate either a presence or absence of the chemical compound.

According to reports, dogs have previously shown that they can sniff out diseases such as cancer, malaria and epilepsy. The dogs use their remarkable sense of smell which can pick up the equivalent of half a teaspoon of sugar in an Olympic-sized swimming pool.

“Dogs could be a great way to screen a large number of people quickly and prevent Covid-19 from being re-introduced into the UK,” Reuters quoted Steve Lindsay, a professor at Durham University’s department of biosciences who worked on the study as saying. Led by James Logan, a disease control specialist, the researchers said that a major advantage of sniffer dogs over other screening methods is their “incredible speed and good accuracy among large groups of people.”

Similar pilot projects involving dogs are underway in Finland, Germany, and Chile. “The highest-performing dogs in the trial detected coronavirus odour in the samples with up to 94.3% sensitivity, meaning a low risk of false-negative results, and up to 92% specificity,” researchers added.

As part of K9 units, Indian Army dogs have also sniffed out Covid-19 positive patients, detecting 22 out of a total sample of 3,800 last year. The Indian Army had trained dogs for detecting Covid-19 cases by smelling urine and sweat samples since September last year after a surge in Covid cases in the force. The dogs are being used to augment the testing capabilities to identify the positive cases early and isolate them before the usual RT-PCR test results come.