When Lee Lee developed a raspy cough three weeks ago, there were only a handful of coronavirus cases in Australia. No one was talking yet of social distancing, but when Mrs. Lee’s doctor swabbed her for a coronavirus test, she and her husband got to thinking.

If hospitals were to become overwhelmed and their grandchildren or great-grandchildren got sick, doctors would face a terrible choice.

“It occurred to us that if push came to shove, although we are certainly not tired of living, we’ve had a pretty good bite and we’d want the limited resources given to them rather than taking them ourselves,” Mrs. Lee said.

So though her test came back negative, Mrs. Lee, 72, a former human resources consultant, and her husband, Colin Lee, 86, a former police officer, decided to self-isolate. No more volunteering or group lunches, nothing really, beyond the backyard of their home in Geelong, outside Melbourne, where socializing was reduced to a tree filled with rainbow lorikeets.