I used to pay social security in Suzhou, but now I pay social security in Changshu. It turns out that the citizen card in Suzhou is medical insurance.

Social security card is citizen card. The citizen card needs to be collected in person, and the way of mailing is very unsafe, because the medical insurance has no password. Your citizenship certificate has come down. You can't do it anymore. You'd better get it. If you can't get it, report the loss and reissue a new card. As long as the previous social security is paid, it will be in it and will not be lost. However, the social security of Suzhou City, Suzhou Park and Wujiang has not yet been interoperable. I don't know if the citizen card you mentioned is from Wujiang or Suzhou, but it's basically the same.

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