Covid-19: “detector” dogs tested at an airport

A French study has already shown that dogs are well able to identify people affected by Covid-19. In a new scientific article published on May 16, 2022 in BMJ Global HealthFinnish researchers and the Frenchman Loic Desquilbet from the Department of Biostatistics and Clinical Epidemiology (National Veterinary School of Alfort) show that dogs can be used successfully at an international airport to combat the spread of coronavirus.

A solid triple-blind study

Humans infected with coronavirus can be asymptomatic but still contagious, and therefore it is necessary to implement fast and cheap means to detect them, unlike the PCR test. “Dogs are thought to detect different volatile organic compounds (VOCs) released by their hosts’ metabolic processes under different conditions“, especially during infections, this study is reminiscent of. Detection can take place when a person is affected by Covid-19, a discovery underlined by French work.

The Finnish researchers wanted to provide new, extremely solid data to finally determine dogs’ olfactory ability in the fight against the coronavirus pandemic. For this, they performed a randomized, triple-blind study (the driver of the dog, the experimenter and the researcher responsible for data processing do not know which test is positive) and a full-scale test at Helsinki-Vantaa airport. with four dogs.

The triple-blind protocol included four identical sets (for each animal) of 420 skin samples (gauze was washed on the neck, forehead and wrists) from 114 positive and 306 negative individuals (tested by PCR), presented randomly to dogs during seven work sessions. In addition, 303 travelers from Helsinki-Vantaa Airport were indirectly “scanned” by the dogs from the end of September 2020 to the end of April 2021. “The survey was conducted in a specially designed and built cabin at the arrival terminal“. It included three separate sampling rooms and the canines were not in contact with the travelers who performed a PCR test at the same time.

Dogs disturbed by the alpha variant

Overall, the diagnostic accuracy of all sniffed samples was 92% for the triple-blind study. Regarding the test at the airport, the results obtained by PCR and by the dogs were identical in 98% of the cases. The dogs correctly detected 296 of the 300 negative samples. Regarding the seven errors: Three positive samples were ignored by the animals. And they also “marked” four samples that were actually negative.

The only variable strongly associated with the inability to identify Covid-19 positive samples was the alpha variant. In fact, according to the epidemiological situation in our country, the virus variants only started to appear at the end of our validation sample collection period.“, emphasize the Finnish researchers. The dogs had only been trained to detect samples from patients infected with the original virus. But the authors of this new study also see there the dogs’ incredible odor ability.

This observation is remarkable because it proves the strong discriminatory power of dogs. The obvious implication is that training samples must cover all epidemiologically relevant variants. Our preliminary observations suggest that dogs ‘primed’ with one type of virus can be retrained within a few hours to detect its variants«, They assure.

They indicate that dogs can eventually be used both in places with a high incidence of coronavirus (eg hospitals) and places with a low incidence (airports, ports).

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