Chilean police officers and trainers work with two dogs, named Keylin and Clifford, at Carabineros de Chile Dog Training School in the Parque Metropolitano in Santiago, Chile, on July 17, 2020, where dogs are being trained to detect COVID-19. #

Rob Harris, a Medical Detection Dogs trainer standing behind the screen, runs a training exercise with Florin. Harris is looking into whether dogs could play a role in preventing the spread of COVID-19, in Milton Keynes, England, on March 31, 2020. #

A trainer from the canine service of Russia's Aeroflot carrier trains a sniffer dog to detect coronavirus in biomaterial from infected people, during a training exercise at Moscow's Sheremetyevo International Airport on October 9, 2020. #

A police handler and his COVID-19 sniffer dog give a demonstration at the Arturo Merino Benítez International Airport in Santiago, Chile, on December 21, 2020. Coronavirus sniffer dogs were set to start working at the airport the following day, according to the interior minister’s office. #

A trainer from the canine service of Aeroflot airline trains a sniffer dog to detect the coronavirus near Sheremetyevo International Airport, outside Moscow, Russia, on October 9, 2020. #

Floki, an English Springer Spaniel, is one of two South Australian dogs taking part in the COVID-19 detection training at the University of Adelaide in Adelaide, Australia, on September 18, 2020. Researchers from the School of Animal and Veterinary Sciences are working to train sniffer dogs to detect COVID-19 in people. #

A dog looks on as it is taught to find a piece of fabric with COVID-19 during a training session on May 13, 2020, in Maison-Alfort, on the outskirts of Paris, France. #

A dog is trained to detect COVID-19 in people as part of a 23-day program carried out by six instructors and nearly 20 staff members, in coordination with the Iranian health minister and the army, at the SK-9 Dog Training Center outside of Tehran, Iran, on May 29, 2020. #

Robert Zacharz and three-year-old Erec Junior rest in the grass with Giulia Gausemann and five-year-old Vine at the training site for sniffing dogs of the German Army, in Daun, Germany, on July 24, 2020. The dogs wear protection goggles against the sun and dust. #

A member of the fire brigade's Cynotechnical Unit trains a dog to sniff out COVID-19 at the national veterinary school of Alfort on October 15, 2020, in Paris, France. #

The sniffer dogs Valo and E.T., who are trained to detect COVID-19 in arriving passengers' samples, sit next to their trainers at Helsinki Airport in Vantaa, Finland, on September 22, 2020. #

A trainer from the canine service of Russia's Aeroflot carrier trains a sniffer dog to detect COVID-19 near Moscow's Sheremetyevo International Airport on October 9, 2020. #

Freya correctly detects a sample of malaria from a row of sample pots at the Medical Detection Dogs charity headquarters on March 27, 2020, in Milton Keynes, England. The charity was working with the London School of Hygiene and Tropical Medicine to test whether the dogs can be re-trained to provide a rapid, non-invasive diagnosis of COVID-19. #

A member of the fire brigade's Cynotechnical Unit works with a dog he is training to sniff out COVID-19 at the national veterinary school of Alfort on October 15, 2020 in Paris, France. #