A proof-of-concept investigation published in PLOS ONE suggests that specially trained detection dogs can sniff out COVID-19-positive samples with 96 percent accuracy.
Source: Vet Practice, April 20, 2021. Link. “Dogs have to be specific about detecting the odor of the infection, but they also have to generalize across the background odors of different people: men and women, adults and children, people of different ethnicities and geographies.”