According to a study published in the journal BMJ Global Health, sniffer dogs can accurately detect airport passengers infected with covid.

In 2020, researchers from Finland’s University of Helsinki and Helsinki University Hospital trained four dogs to detect SARS-CoV-2. Each dog had been previously taught to detect illegal narcotics.

To put the dogs’ detection skills to the test, 420 volunteers each provided four skin swab samples.

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The four dogs sniffed skin samples from 114 volunteers who tested positive for SARS-CoV-2 on a PCR swab test and 306 volunteers who tested negative.

The samples were given to each dog at random throughout seven trial sessions.

The combined sensitivity accuracy of detecting those with the infection was 92%, and the combined specificity was 91%.

The researchers claim that 28 of the positive samples came from people who had no symptoms. The samples were correctly identified in 89 per cent of the cases. The absence of symptoms did not affect the dogs’ performance.

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Between September 2020 and April 2021, the four dogs were put to work sniffing out 303 incoming passengers at Helsinki-Vantaa International Airport in Finland.

Each passenger also went through a PCR swab test.

In 296 out of 303 (98%) of the real-life samples, the PCR and sniffer results matched.

The dogs correctly identified the samples as negative in 296 out of 300 (99%) PCR negative swab tests and three PCR positive cases as negative, according to the researchers.

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Similarly, the dogs identified four PCR negative cases as positive.

All of these were found to be SARS-CoV-2 negative.

Based on these findings, they calculated the proportion of positive predictive value (PPV) and the proportion of negative predictive value (NPV) in two hypothetical scenarios with SARS-CoV-2 population prevalences of 40% and 1%, respectively.

They calculated a PPV of 88% and an NPV of 94.55% for a 40% prevalence.

This means that the dog’s information increases the likelihood of detection to around 90%.

For a population prevalence of 1%, they estimated a PPV of just under 10% and an NPV of just under 100%.

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According to the researchers, the high NPV in both scenarios supports the use of sniffer dogs for screening to exclude people who do not require a PCR swab test.

This form of detection, according to the researchers, is likely to be effective in the early phases of a pandemic when other resources are not yet available.

Dogs are thought to be capable of detecting certain volatile organic chemicals produced by bacterial, viral, and parasite infections, as well as other metabolic processes in the body.