“There’s the distinct possibility that things will get out of control in China,” John Swartzberg, a professor emeritus of infectious diseases and vaccinology at the University of California-Berkeley’s School of Public Health, told The Daily Beast. “If that happens,” Swartzberg added, “there will be a remarkable amount of viral reproduction occurring in people and this will increase the possibility of problematic variants being produced.”

Experts disagree just how likely it is that the next major variant—“lineage” is the scientific term—might emerge in China. Ben Cowling, a professor of epidemiology at The University of Hong Kong, said the next major lineage may come from countries where the virus has already swept through the population. Somewhere in Europe, or the U.S.

But there are unique dynamics that boost the chances of a new SARS-CoV-2 lineage appearing in China. The Chinese population is huge—and might be way less protected against infection and thus viral mutation than, say, Americans or Europeans.