Qiang Yang, a professor at the Hong Kong University of Science and Technology, was looking forward to AAAI, one of the big artificial intelligence conferences, which takes place in New York this week.

Yang was due to present an award-winning paper describing a way for an AI algorithm to perform image recognition by drawing from different data sets without ever revealing their contents. He decided to cancel his trip due to the global health emergency triggered by the coronavirus in China. Yang estimates that around 800 attendees from mainland China, about a fifth of the 4,000 registered for the conference, will miss the event due to a travel ban imposed by the US on Monday.

“It’s a big pity,” Yang says via WeChat from his home in Hong Kong. “In a way it shows how AI advancement depends on the efforts from both the US and China, among others. AI is truly a global effort.”

The World Health Organization declared the coronavirus a global health emergency last week. The deadly and contagious virus has infected more than 24,000 people, killing 490, with more than 3,000 in a critical condition, according to the latest information from the China’s National Health Commission.

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With the virus still spreading rapidly from its epicenter of Wuhan, much of China has effectively ground to a halt as businesses suspend operations and people remain indoors. But the global nature of modern supply chains, research operations, and academic work means that ripple effects are spreading across business and technology even more rapidly.

A spokesperson for the American Association for Artificial Intelligence, which organizes the event, was unable to say precisely how many researchers from China were due to attend this year. Yang says that many of the Chinese researchers who will miss the event have chosen to stay up all night in order to present via video call instead.

The effect of the outbreak on the AAAI conference shows the strength that China has built up in fundamental AI research in recent years. China already produces more scientific papers on AI than the US, and research published last March by the Allen Institute for Artificial Intelligence suggests that the quality of those papers is rising rapidly.

The absence of many Chinese researchers is undoubtedly bad for progress in AI and the industry this drives. As one of the year’s most prominent and popular gatherings, AAAI is an important place to discuss important ideas, hatch startup plans, and hire hotshot students.

The situation points to a close relationship that still exists between US and Chinese academia, despite the competitive tension felt by the governments in Washington and Beijing. Few areas of technology are not somehow tied to China. The country is a major hub of manufacturing and business but increasingly also an epicenter of research.

At a photonics industry event held in San Francisco this week, for instance, some Chinese companies were in attendance, having arrived before travel restrictions went into effect. But the show floor also had to be hastily rearranged, with plants and seats replacing booths, to hide the fact that other Chinese companies were unable to come.

Prolonged travel restrictions will affect many technologies that rely on international collaboration and competition. Both LG and ZTE announced this week that due to the coronavirus they will be absent from another global tech and business gathering, Mobile World Congress. Held at the end of this month in Barcelona, the event is a major showcase for advanced smartphones and communications technologies, including the next-generation wireless technology known as 5G.

The situation has also upset automotive manufacturing and supply chains. GM, Toyota, Tesla, and the world’s largest automotive company, VW, have closed factories in China. Hyundai was also forced to suspend manufacturing in South Korea due to a shortage of components coming from China.