On March 30 (local time), The World Health Organization (WHO) released a report on the global tracing of COVID-19 origins in Geneva. According to the report, COVID-19 introduction through a laboratory incident is "extremely unlikely". Nonetheless, it is important to investigate potential early events in other countries.

A total of 34 experts from the WHO and 10 countries, including China, jointly conducted a 28-day study from January 14 to February 10 in Wuhan, China, aiming to conducted the research in the areas of: epidemiology, animals and the environment, and molecular epidemiology and bioinformatics.

The joint team assessed the relative likelihood of these four pathways and the assessment of likelihood of each possible pathway was as follows: introduction through a laboratory incident was considered to be “an extremely unlikely” pathway; direct zoonotic spillover is considered to be “a possible-to-likely” pathway; introduction through an intermediate host is considered to be “a likely to very likely” pathway; introduction through cold/ food chain products is considered “a possible pathway”;

The report also finds that “transmission within the wider community in December could account for cases not associated with the Huanan market which, together with the presence of early cases not associated with that market, could suggest that the Huanan market was not the original source of the outbreak”. In addition, “no firm conclusion therefore about the role of the Huanan Market can be drawn.”

Besides, evidence from surveys and targeted studies so far have found “most highly related viruses in bats and pangolins, suggesting they may be the reservoir of the novel coronavirus” according to the high sequence similarity between the sampled viruses and the novel coronavirus. However, “viruses identified so far from neither bats nor pangolins are sufficiently similar” to the novel coronavirus to “serve as the direct progenitor” of the novel coronavirus”. In addition to these findings, “the high susceptibility of mink and cats suggests the potential of additional species of animals (belonging to the mustelid or felid family, as well as other species) as potential reservoirs”.

The report says that the novel coronavirus has been found to “persist in conditions found in frozen food, packaging and cold-chain products. Index cases in recent outbreaks in China have been linked to the cold chain; the virus has been found on packages and products from other countries that supply China with cold-chain products, indicating that it can be carried long distances on cold-chain products”.

Finally, the team reviewed data from published studies from different countries suggesting early circulation of the novel coronavirus. The findings suggest that circulation of the novel coronavirus “preceded the initial detection of cases by several weeks. Some of the suspected positive samples were detected even earlier than the first case in Wuhan, suggesting the possibility of missed circulation in other countries”. So far, however, “the quality of the studies is limited”. Nonetheless, “it is important to investigate these potential early events”.

The joint international team also made several recommendations, including establishing a unified global database, tracing earlier cases continuously in a broader sense around the globe, searching for animal species that could be possible hosts for the novel coronavirus in multiple sites and multiple countries by scientists around the world, and further exploring the function of cold chain and frozen food in the transmission process of the virus.

After receiving the report, the WHO Director-General Dr. Tedros Adhanom Ghebreyesus expressed his gratitude to the joint team, including Chinese scientists, and said that “we have not yet found the source of the virus, and we must continue to follow the science and leave no stone unturned as we do”.

At 4 o’clock p.m. March 30 (local time), the WHO hosted an online press conference and invited experts to answer questions regarding the report. The reporter from Science and Technology Daily raised a question: “How do you evaluate the work of the Chinese team?”

Dr. Peter Daszak, member of the the WHO expert group, responded that “by looking at the volume of the data collected, the rigor of the methods used, the quality of the teams working on them, and their ability to discuss and interpret the findings at a very high international scientific standard”.