Trained sniffer dogs can accurately identify airport passengers infected with coronavirus, new research suggests.
Scientists say this method of detection is likely to be especially valuable, not only in the early stages of a pandemic when other resources might not yet be available, but also to help contain an ongoing pandemic.
They add that their findings highlight the importance of continuous retraining as new Covid-19 variants emerge.
Preliminary data suggested dogs could be trained within weeks to detect samples from patients with Covid-19 infection, with a degree of accuracy comparable to a nose and throat swab test.
But these results needed to be replicated in real-life conditions, so researchers trained four dogs – previously trained to detect drugs or dangerous goods, or cancer – to sniff out the virus in spring 2020.
The animals each sniffed skin samples from 114 people who had tested positive for the virus and from 306 who had tested negative.
According to the study, led by experts at the University of Helsinki, Finland, overall the dogs were able to detect the virus with 92% accuracy.
The four dogs were also put to work sniffing out 303 incoming passengers at Helsinki-Vantaa International Airport between September 2020 and April 2021.
The dogs correctly identified the samples as negative in 296 out of 300 (99%) negative tests and identified three positive cases as negative.
Writing in BMJ Global Health, the researchers suggested “dogs could be used both in sites of high Sars-CoV-2 prevalence, such as hospitals (to prescreen patients and personnel), as well as in low prevalence sites, such as airports or ports (to prescreen passengers).”
A key finding was that the dogs were less successful at correctly identifying the alpha variant as they had been trained to detect the wild type.
The researchers added: “This observation is remarkable as it proves the scent dogs’ robust discriminatory power.
“The obvious implication is that training samples should cover all epidemiologically relevant variants.
“Our preliminary observations suggest that dogs primed with one virus type can in a few hours be retrained to detect its variants.”