The challenge was first raised by Dutch microbiologist Elizabeth Bik on Twitter, where she pointed to duplications on the computer-scanned images from the papers.

“Reported to @ASMicrobiology (The American Society for Microbiology) [and] @JVirology (The Journal of Virology) in 2017, but the editors did not answer, nor did they take action,” Bik tweeted on August 1.

Speaking to the media on Wednesday, Yuen admitted he received an email earlier, in which he was informed that the similarity of the protein tracking exceeded their predicted levels in seven research articles.

He added he later spoke to the research team and believed the team mixed up or duplicated the samples when scanning the protein tracking to the computers.

He continued the incident didn’t involve patients’ treatments, but affected studies in the future. As the experiments could not be performed again, the university decided to retract the five articles.

The articles were published between 2010 and 2014 and most of them were about studies on the coronavirus, including the Middle East Respiratory Syndrome. One of the articles published in 2014 was about the coronavirus found in dolphins.

Apart from Yuen, authors of those articles included Woo Chiu-yat, the former chair of HKU’s Department of Microbiology.