Chongqing- November 4. Teams of medical workers have been working around the clock ever since Chongqing was suddenly caught amidst the latest outbreak. A 90's generation epidemiology investigator, Luo Lin, sleeps in the cold with her back leaned against a wall following a whole night on duty.

"I'm sorry. I just couldn't help it." She reacted with a touch of embarrassment before the journalist's camera. She had caught up on a few minutes' sleep during her break before immersing herself back into her duties as an investigator.

Luo Lin (Left) is a member of an epidemiological investigation team dispatched from the Chongqing Center for Disease Control. In the above photograph, they have arrived at a location nearby 53 Hucai Road.

Where does the confirmed patient come from? Where has he visited? Where did he go after? These are questions team members habitually ask during their thorough investigations.

"This restaurant was visited by patient number three, so according to the principle of tracing close and secondary contacts…." Investigation teams explain as they complete their questions, environmental sampling, and disinfection work.

"The second table on the left." Once the position has been ascertained, no stone is left unturned as they identify all possible articles touched by the patient, including the table surface, chairs, and tissue boxes.

Not only are environmental samples taken from the scene. Since all staff are potential close and secondary contacts of the patient, they also need samples taken for nucleic acid testing on site.

"How many people were inside at the time? Do you have camera footage? Which customers were still dining around 11 o'clock?" Thorough questioning means that possible contacts of the patient can be traced more accurately.

While they await the results of sampling and investigations, every nook and cranny is targeted for thorough disinfection, from small items like tissue boxes to whole public spaces within the restaurant.

Environmental samples in the living quarters of primary and secondary contacts are taken once they have been identified. In the photograph above, investigators walk towards the home of close contact.

Environmental samples taken from the living quarters of primary contacts allow them to quickly trace the chain of transmission and identify more potential contacts, which in turn means they can issue prompt deployments in the next step to pre-empt further infections.

"Door handles. Switches. The bathroom….." All the environmental samples taken correspond to a barcode listed on a clipboard so that no object goes unattended.

Team members completed their investigation at the current site after two hours, while people assessed to be primary contacts were moved to centralized quarantine facilities for observation. The coordinators must now hurry back to their headquarters, where they will trace more clues in the race to prevent further transmission.

(Wang Wei, Shi Tao, CQ News)