However , because they do not have social security ( because of the hukou system ) , many of them do not have health insurance .
During this time , more and more migrant workers from rural areas have moved to cities such as Shanghai to find jobs .
Because they do not have social security ( because of the hukou system ) , many of them do not have health insurance .
During this time , more and more migrant workers from rural areas have moved to cities such as Shanghai to find jobs .