When he got there, local officials directed him to a cluster of stalls selling wild animals for meat or traditional medicine. There were carcasses and caged live specimens, including snakes, dogs, rabbits and badgers, he said.

As his team started to spray disinfectant, the officials began taking samples from the stalls, sewers and goods, Mr. Lu says. They got his team to help with the dead animals, picking out feces and fur with tweezers, and sealing them in plastic bags.

More than four months later, Chinese officials have yet to share with the world any data from the animals Mr. Lu and others say were sampled.

The question this raises is: Why won’t China share the data it has? It seems especially perplexing given the major role the origin of the virus has played in the back and forth between China and the United States for several months.

Chinese propaganda began spreading the idea that the origin of the virus was unknown and then conspiracy theories took hold which blamed the entire global pandemic on an American woman named Maatje Benassi. President Trump pushed back on some of the Chinese propaganda by referring to it as the “Chinese virus” but that was quickly deemed “xenophobic” by the American media.

Then there was a very public debate about whether the virus had originated in the Wuhan wet market or was released accidentally from a local laboratory which was studying bat corona-viruses. China has firmly denied the lab release scenario but has also clamped down on all research into the origins of the virus.

Given all that has happened, you would think China would be eager to release data proving that the virus originated in the market. But thus far it hasn’t released the data to anyone.

China has only made public the genetic sequences of “environmental samples” from the market’s sewers, stalls and a garbage truck—not material directly from any animals—Chinese and foreign researchers say. Some say they’ve been told by Chinese officials that animals taken from the market were destroyed. Several Huanan market vendors said they had not done tests to establish how many of them were infected.

Although Chinese officials said they were tracing the suppliers of wild meat in the market, they have not published any information on those people or animals they handled.

The World Health Organization has taken China’s word as gospel throughout the crisis but when WHO offered to join to investigation into the origin of the virus, China said no. Plans to map the origin of the virus based on samples have yet to bear any fruit.

However, the WSJ says there are indications what the results of China’s wet market tests were, even if China won’t release the information. A Columbia University virologist said his counterparts in China told him the examination of samples from animals at the market didn’t reveal a clear origin:

Dr. Lipkin, who also helped tackle SARS, said that George Gao, the China CDC chief, was initially convinced that the culprit was a bamboo rat, a rodent often sold as meat in China.

“After they went through and did this exhaustive search of the live and the dead and the frozen animals in various freezers, and they didn’t come up with anything, they had to revise their model,” said Dr. Lipkin.

He said Dr. Gao had told him that Chinese scientists had found the virus in the environmental samples but had been unable to identify which animal they likely came from.

That conclusion is backed up by meeting minutes from a Paris-based group called the World Organization for Animal Health, of which China is a member. The group met on Jan. 31 and, according to minutes of the meeting, learned that animal samples from the market had been tested but that none had tested positive for the virus.

This could explain why China won’t release the data it has. In the current context, if China revealed that animal samples taken from the market on the day it was closed were negative for the virus, that would be taken as evidence that the market was perhaps not the origin point of the virus. It might even be taken as strengthening the case for an accidental lab release, something China has strenuously denied. So you can see why they might prefer to sit on this information at the moment.

China either knows where the virus originated and doesn’t want us to know or it doesn’t know where the virus originated and doesn’t want us to know that it botched the investigation back in December. Either way, the bottom line is that revealing the data would make China look bad. That would be a major negative at a moment when the communist government is a) determined to look like a world leader and b) very worried about the backlash to its initial failures surrounding the virus. Right now, Xi Jinping would rather China’s actions look suspicious than confirm that its actions were incompetent.