Do Chengdu basic medical insurance and serious illness medical insurance have to be purchased together?

Do Chengdu basic medical insurance and serious illness medical insurance have to be purchased together? Hello! In the process of social security payment, in fact, the payment of basic medical insurance has been bound with serious illness medical insurance. 202 1 basic medical insurance and critical illness insurance are not merged, but they are still paid in two types of insurance, but generally speaking, these two types of insurance should be paid together. People who are not retired are not allowed to pay a separate insurance policy. Retirees who have paid enough basic medical insurance can pay serious illness insurance separately. Serious illness insurance is a supplement to basic medical insurance, which has stronger guarantee ability and is generally paid.