How bad is the Covid outbreak in China? It's a scientific guessing game.

In the absence of credible information from the Chinese government, researchers around the world are looking for clues to determine the scale and severity of the push.

As Covid sweeps through China, scientists around the world are searching for clues to an outbreak with sprawling consequences - for the health of hundreds of millions of Chinese, the global economy and the future of the pandemic.

But in the absence of credible information from the Chinese government, it's a big scientific guessing game to determine the scale and severity of the outbreak in the world's most populous country.

In Hong Kong, a team of researchers looked at data from passengers on five Beijing subway lines to determine the potential spread. In Seattle, a group of modellers unsuccessfully tried to reverse engineer an unverified government leak detailing case numbers from Chinese health authorities. In Britain, scientists are offering their own estimates of the effectiveness of Chinese vaccines.

Any personal anecdotes or social media reports from China - rare drugs, Overwhelmed hospitals, overwhelmed crematoria - is possible fodder for researchers' models.

They are all trying to figure out the same things: how fast the virus he in the country? How many people die? Could China be the source of a dangerous new variant?

The ImageCovid-19 patients in the hall of the Chongqing No. 5 People's Hospital in the southwest city of Chongqing in December. through various sources of fragile information, they prepare for potentially catastrophic outcomes. Barring new precautionary measures, some worst-case estimates suggest that Covid could kill as many people in China over the next four months as Americans during the entire three-year pandemic.

Without satisfactory answers, some countries are imposing limits on Chinese travelers, albeit based in part on unfounded fears or political motivations. The United States, Italy and Japan have said they will require a negative Covid test for those coming from China, fearing that rising cases in China could produce new, more threatening variants.

< p class="css- at9mc1 evys1bk0">While researchers and virologists have said the new measures are unlikely to do much, if anything, to mitigate the spread, the policies reflect the limited visibility of the outbreak. The scientists' models generally point to an explosive spread and high death rate, given the number of people in China who have little or no immunity to Omicron subvariants. But even their estimates are everywhere.

In the darkest of several scenarios of what the end of China's "zero Covid" policy could mean, nearly one million people could die in the first months of reopening, Hong Kong researchers reported this month in a study partly funded by the Chinese Center for Disease Control and Prevention.