Here's a story to cheer you up: covid detection dogs

Medical detection dogs have been around for some time. They mostly work in hospitals, sniffing body fluid (e.g. urine) samples and announcing when they can detect a specific odour that indicates cancer or some other disease such as Parkinson's. They are often amazingly accurate. Like drug-detection dogs, they are mostly springer spaniels.

For covid detection, you need a different kind of dog, one that likes being out and about and is not fazed by crowds or heavy traffic. Those are among the characteristics of a good guide dog. But guide dogs also need to be calm, low energy and not overly curious, so some pups in training turn out to be unsuitable. Now three "failed" guide dog pups are being retrained as covid-sniffers.
This article includes some lovely pictures.