In this type of low-prevalence environment, you want dogs to be able to screen passengers with a high “negative predictive value”. That is, you want the dogs to be able to identify people who are not carrying the virus to differentiate them from those who may be carrying it. Then you would carry out confirmatory PCR testing on that last group.
In an environment where the prevalence of COVID-19 is around 1 per cent, such as an airport, the researchers estimated the “negative predictive value” for dogs screening for COVID to be 99.9 per cent. That is, the dogs would be expected to correctly exclude 99.9 per cent of passengers as having COVID-19. This is another fantastic result.
ACCURATE AND INSTANT RESULTS ARE VALUABLE
In a world where we rely on expensive technological solutions, there is something reassuring about finding a low-tech option for screening COVID-19.
Importantly, however, the study highlights dogs are quick to train for this task and are ideal for screening in high-throughput settings, such as airports, given how accurate they are and the fact they give instant results.
Although nothing should surprise us about our closest friend, another incredible outcome from this study was the suggestion the dogs may have been able to distinguish between the variants of SARS-CoV-2, the virus that causes COVID-19.
While other possible explanations cannot be excluded, the performance of the dogs seemed to drop with the emergence of the Alpha variant. This was attributed to the dogs being able to identify a difference between this variant and the wild-type virus on which they were originally trained.
These studies confirm nothing could be further from the truth when we say you can’t teach an old dog new tricks.
Hassan Vally is an Associate Professor in Epidemiology at Deakin University. This commentary first appeared in The Conversation.