New Delhi, Jan. 21 -- Last month a friend called to say that she had forgotten to renew her health insurance. With the break, the insurer refused to renew her cover because she had previously had cancer. A decade ago, I often urged people to buy health insurance. Some felt that medical costs were manageable. Others opined that claims would not be paid. That worldview has changed because medical inflation is in plain sight and millions have benefited from insurance.

Today, people worry most about how to get insured if they have been diagnosed with a health condition. They shouldn't. Insurers are now good at understanding and insuring people with adverse health. These are recorded in the policy as 'pre-existing health conditions'. But what...