Is it illegal to close the door and quarantine after receiving a text message from the virus stream a week later without any response?

It's not illegal. This is an emergency.

Epidemiological investigation is an important link in epidemic prevention and control. To carry out epidemiological investigation, it is necessary to communicate face to face with patients and related personnel, ask patients about their exposure history, activity track, medical treatment before and after illness, and look for clues related to the source of infection and transmission route, so as to provide basis for judging close contacts, taking isolation measures and determining disinfection scope. According to the relevant laws and regulations, citizens have the legal obligation to cooperate and support this work and provide real and detailed information to the flow-regulating personnel.

In-depth investigation refers to face-to-face investigation with the case, on-site investigation of workplace, residence, activity track and other places related to the case, and big data investigation with the support of the public security department, which is an important part of the investigation.