The yellow code of health code is not necessarily infected with COVID-19 virus. The yellow code is a warning color. As long as it is proved that COVID-19 is not infected, it is generally unnecessary to isolate people whose health codes show yellow codes, but it will restrict their travel to some extent. For example, people with yellow health code are not allowed to enter shopping malls, hotels, supermarkets, stations, airports, cinemas, KTV, bars and other public places.