Developments over the past week may push the World Health Organization to issue a global alert over the coronavirus, after the agency last week stopped short of calling it a health emergency, according to a public health specialist.

Evidence that the disease can be transmitted before a person shows any signs of illness could make a difference as WHO’s emergency committee meets later Thursday to determine whether or not the outbreak constitutes a so-called public health event of international concern, said Raina MacIntyre, a professor of global biosecurity at the University of New South Wales in Sydney.

“They may come out and declare a public health emergency particularly because of the new findings that pre-symptomatic transmission can occur,” McIntyre said in a phone interview Thursday. “That brings a more complex issue to disease control. It becomes much harder to control infection where you have got transmission without symptoms.”

While the majority of cases are occurring in mainland China, the increase of infections in other regions around the globe might also factor into the WHO committee’s discussions, she said.

An emergency declaration by the WHO would allow the agency to begin coordinating government responses. It also could recommend travel and trade restrictions to stop the spread of the infection. But MacIntyre pointed out that the regulations aren’t enforceable.