Is insurance covered by social security or not?

No, but if you buy the medical reimbursement model, you may have been cheated, because some medical insurance will be cheaper if you have medical insurance, but it will be more expensive if you don't. Of course, if they have medical insurance, they must report the case to the insurance company first, and then settle the claim, otherwise the claim will be discounted.

Further reading: How to buy insurance, which is good, and teach you how to avoid these "pits" of insurance.