In early January, a Tokyo man in his 80s with diabetes tested positive for COVID-19.

He soon started to have difficulty breathing. But with hospital beds filling up fast, public health authorities couldn’t immediately place him under medical care.

Then he showed moderate signs of recovery, which emboldened officials to decide that he could, after all, remain at home to recuperate — despite the capital’s guidelines saying that those age 70 or older with an underlying condition should in principle be hospitalized.