MILWAUKEE (AP) — Travel restrictions and business closures aimed at stopping the spread of a new virus that has killed more than 300 people in China could end up causing ripple effects that harm the global economy, experts say.

“When you stop planes and ships, trains and and motor vehicles from moving, it starts to shut down the economy — and that can have a cascading effect throughout society,” Dr. Eric Toner, senior scholar at the Johns Hopkins Center for Health Security, said Saturday, after multiple airlines announced that they would suspend or cut back on flights to and from China, and several countries, including the U.S., imposed travel restrictions. “And it’s not just airline pilots who get out of work, I mean, it’s you know, it’s everybody that they depend on.”

It’s not just airlines that have cut back on business in China. Apple Inc. announced Saturday that it was temporarily close all of its offices and its 42 stores in mainland China. Google, Amazon and Microsoft previously announced plans to temporarily shutter offices, and Starbucks and McDonald’s have closed some chains.

Apple said it was acting “out of an abundance of caution and based on the latest advice from leading health experts.” Its stores will be closed until Feb. 9.

Toner said Apple’s decision could also be harmful to the economy and Apple itself, though he noted that many companies, including airlines, are trying to protect their employees.

Toner led a summit in October with World Economic Forum and the Bill and Melinda Gates Foundation to discuss the negative impacts of trade and travel restrictions during a pandemic. In a paper that came out of that meeting, the Johns Hopkins Center for Health Security concluded that “fear and uncertainty experienced during past outbreaks, even those limited to a national or regional level, have sometimes led to unjustified border measures.”

The U.S., Australia, Singapore and Japan have imposed travel restrictions and Vietnam suspended all flights to China. U.S. officials pointed to how quickly the virus has spread around the globe as justification, although world health officials have warned against such measures.

At least 24 countries have reported cases of the new virus, which is from the coronavirus family.

“Travel restrictions can cause more harm than good by hindering info-sharing, medical supply chains and harming economies,” World Health Organization Secretary-General Tedros Adhanom Ghebreyesus said.

Toner said governments are ultimately “trying to do something that has very little benefit but very real harm.”

“It’s been shown over and over again that putting up barriers to travel doesn’t stop contagious infectious diseases,” he said, pointing to past outbreaks of Ebola, Zika and even influenza.

Instead, he said, governments should educate people about the virus and urge people who may have been exposed to isolate themselves.