Medical personnel collect throat swabs from local residents in Tianjin Binhai New Area. Photo: AFP

A local Tianjin health official who has been dubbed China's Sherlock Holmes has cracked the mysterious case of the latest COVID-19 infections in North China's Tianjin, and helped clear up suspicions over German pork knuckles, which were previously believed to be the source of the recent infections. 

Zhang Ying, deputy director at the Tianjin Centers for Disease Control and Prevention, outlined the epidemiological investigation at Tuesday's media briefing and said the recent infections were caused after pig heads from North America infected pork knuckles from Germany. 

Zhang noted that they received reports from Dezhou, Shandong Province, that a batch of pork knuckles imported from Germany via a port in Tianjin was coronavirus-positive. Tianjin then screened Hailian cold storage and found two confirmed cases. 

Many people then believed that the pork knuckles from Germany must have been the source of the recent infections, while the German Ministry for Food and Agriculture said that the chances of German pork knuckles triggering a coronavirus case in China is unlikely.

However, following investigations showed that the two confirmed patients had no direct contact with one worker who loaded pork knuckles from No.4 storage or the other who transported pig heads from No.6 storage. 

Zhang's team traced the date of when the pig heads from North America and German pork knuckles arrived in the Hailian cold storage and found that one batch of pig heads had been transported to No.2 storage, while the other batch was transported to No.5 storage via the platform of No.4 storage, where the pork knuckles were stored. 

One confirmed patient, a loading worker at the Hailian cold storage, carried in both pork knuckles and pig heads that had been transported to No.2 storage on November 4, Zhang said. The same worker wearing the same pair of gloves and clothes then carried the pork knuckles the next day, which resulted in the positive result for the pork knuckle packaging in Dezhou, Zhang said. 

However, the worker did not transport pig heads that were stored in No.5 storage. This batch of pig heads, although stored there, was carried out from the door of No.6 storage. The other patient was a truck driver, who became infected after he picked up one pig head that fell to the ground. 

This means that the source for the other patient was pig heads from North America, Zhang said. 

The sources of the recent infections in Tianjin was pig heads imported from North America, which infected the German pork knuckles while they were in the same platform in No.4 storage, resulting in a positive result on the pork knuckle packaging, Zhang said. 

Zhang and her team were assigned a new role of looking for clues in each imported case ever since such cases appeared in China several months ago. She has led her team to trace and visit the sites the patients have been to, collected information on them, carried out in-depth surveys and analysis, and issued public warnings based on their analysis.  

She has successfully located the sources of several imported cases through thorough investigations, earning her the nickname of China's Sherlock Holmes. Several of her news conferences, in which she explains in great detail how cases were detected, were widely followed on social media. 

Global Times