Hong Kong until recently had an enviable record battling Covid-19, but as an Omicron wave now overwhelms the city, the steps that saved lives are making life unbearable for many of its 7.4 million people.

Like an immune system overreacting and harming the person it is meant to protect, the "dynamic zero-Covid" policies that had crushed the virus in Hong Kong have contributed to current woes, experts say.

Patients lie in beds in...