As COVID-19 barrels through China, scientists around the world are searching for clues about an outbreak with sprawling consequences — for the health of hundreds of millions of Chinese people, the global economy and the future of the pandemic.

But in the absence of credible information from the Chinese government, it is a big scientific guessing game to determine the size and severity of the surge in the world’s most populous country.

In Hong Kong, one team of researchers pored over passenger data from five Beijing subway lines to determine the potential spread. In Seattle, a group of modelers tried in vain to reverse-engineer an unverified government leak detailing case numbers from Chinese health officials. In Britain, scientists are coming up with their own efficacy estimates of Chinese vaccines.