What if I don't show my health code in the subway?

Yuekang code application. Health code is a personal two-dimensional code based on actual real data, which is declared by citizens or people who have returned to work through their own online. Generated after background audit. The code is not displayed in the subway, and peers can apply and display it through "Yuekang Code" or "Suikang Code". Subway is a kind of fast, large-capacity and electric traction rail transit built in cities.