You can't take the train without the health code during the epidemic, but in some places, such as Shanghai and Jiangsu, paper health certificates can be issued by communities or designated hospitals, which is equivalent to the health code. People who don't have smart phones can pass the local community audit, build official seals and issue health passes, valid for 14 days. But it is better to prepare the health code in advance to avoid unnecessary trouble.
Health codes in various places basically have the function of collection, which is convenient for the elderly, children and other users without smart phones to travel. You can consult the local community for specific use, and the family will help the elderly and children to handle the health code.