【明報專訊】Provinces and cities in mainland China have established their respective ''health code'' systems one after another, a way of categorising people into different health statuses. Some regions use a two-tiered system that includes a green pass, meaning ''healthy'', and a red alert, meaning ''infected''. A three-tiered system is also used in a number of areas, adding to their system a yellow alert which means ''on examination''. Hong Kong's ''health code'' system is also ready to launch. However, some suspect that the variously designed systems would cause confusion and inconvenience when linked with each other.