Dogs are said to be man’s best friend and there are certainly studies to back it up: they reduce stress levels, keep their older owners active and help them socialise. Now these animals add another task in favor of humanity: prevent the spread of covid-19 thanks to its sense of smell.
A study carried out by researchers from the University Hospital (HUS) and the University of Helsinki (HU) ensures that sniffer dogs can accurately detect airport passengers infected with SARS-CoV-2. The research was published in the open access journal BMJ Global Health.
Preliminary data suggest that the dogs, trained for a few weeks, detect the virus with an accuracy comparable to that of a PCR, the most popular technique to date to find infected people.
Previous articles already pointed out how dogs are capable of detecting different volatile organic compounds released during metabolic processes in the body, including those generated by bacterial, viral and parasitic infections.
Experts suggest their help might be especially useful both for monitoring patients in the early stages of future epidemics – in the absence of other resources – to contain pandemics that are already in progress.
How did they do the study?
researchers trained four dogs to track SARS-CoV-2 in the spring of 2020 in real situations. Each of them had previously been trained to look for illicit drugs, dangerous goods, or even cancer.
First, to test your detection skills 420 volunteers provided skin samples. After performing a PCR, 114 tested positive for SARS-CoV-2 and the rest negative. Samples were randomly presented to each animal during seven testing sessions.
Usually, the diagnostic accuracy of all sniffed samples was 92%, both to detect those who had the infection (sensitivity) and those who did not (specificity).
In the second phase of the study, the dogs were tested at the Helsinki-Vantaa International Airport (Finland), between September 2020 and April 2021. PCR and tracer results agreed 98% of the samples taken at the airport.
Those responsible for the study suggest that “these trained animals might be used both in places with a high prevalence of SARS-CoV-2, such as hospitals, low prevalence sites, airports or ports to save time and resources.
Study limitations
Researchers warn that dogs trained to sniff out other substances they may be confused with SARS-CoV-2. Likewise, “the required storage period of the volunteer samples for the initial training may also have affected the viability of the volatile organic compounds”, they comment.
On the other hand, a key finding was that dogs were less successful in identifying the alpha variant of the virus, since they were trained to detect the primary variant. For the authors, “this observation is significant, since it demonstrates the discriminatory power of the trackers.”
“Our preliminary observations suggest that these animals taught with a particular variant of the virus can retrain in a few hours to detect the rest”, they conclude.
