At present, COVID-19 is not classified as Grade B cold, which will not affect travel. Shenzhen can't check the health code by subway.
How to apply for Shenzhen health code:
1. Open WeChat and click the search icon at the top right.
2. Enter Shenzhen and click the first result.
3. Choose to declare independently.
4. After entering, log in for authorization and click Independent Declaration.
5. Fill in your information.
6. Then click the Health Code menu in the middle of the home page.
7. Finally, you will see your own Shenzhen health code and display it directly when necessary.