The Taiwanese official was getting nervous.

It was Jan. 13, and Chuang Yin-ching, an infectious-disease specialist with the Taiwan Centers for Disease Control, was sitting in a conference room in Wuhan, China, listening to local health officials describe a mysterious new virus.

Chinese health officials had linked the outbreak to a seafood market in Wuhan, and claimed it was not spreading between people. Now the local officials were describing clusters of cases that seemed to suggest human-to-human transmission — but were hesitant to say so.

By the time Chuang returned to Taiwan two days later, he was convinced that China was hiding critical information. The next day, he held a news conference to warn the world.

Taiwan took immediate action. The United States did not.

The United States’ top health official, Health and Human Services Secretary Alex Azar, is in Taiwan this week for the highest-level visit by a U.S. Cabinet secretary since 1979, when the United States cut formal ties with Taiwan to establish diplomatic relations with China.

The trip is meant to signal Washington’s support for Taiwan at a time when the United States and China are at odds over nearly everything. It’s also a chance for the United States and Taiwan to compare notes on the pandemic.

The gap between the democracies is stark: Taiwan, population 23 million, has reported fewer than 500 novel coronavirus cases and seven deaths as of Sunday. The United States, population 328 million, has reported 5 million cases and more than 162,000 deaths.

In an interview with The Washington Post, Chuang described learning of the virus that in less than nine months has infected more than 19.7 million people worldwide and killed more than 729,000.

Much of Taiwan’s coronavirus strategy — masks, contact tracing, testing, quarantine — has been well documented. But Chuang’s testimony about the earliest days of the outbreak offers additional lessons about how Taiwan was able to stop the coronavirus in its tracks — while the United States was overrun.

Taiwan is pushing hard to join the World Health Organization, against objections from China, arguing that it has much to offer the international community on global public health. It’s a campaign the United States has supported, even as the White House seeks to sever ties with the U.N. health agency.

Chuang’s account is a timely reminder that Taiwan warned the world about the coronavirus’s deadly potential early, but few listened. “I was disappointed,” Chuang said.

Like many infectious-disease specialists, Chuang first heard about a mysterious pneumonia in Wuhan in late December. He recalled seeing reports online that Wuhan health officials were ordering hospitals to report all cases — a potentially worrying sign.

On Dec. 31 — days before the first warning from the WHO — Taiwan started inspecting flights from the central Chinese city. The Taiwan Centers for Disease Control formed a task force.

In early January, China linked the mysterious pneumonia to a seafood market and promptly shut it down. Chinese officials said the virus was not spreading between people. The WHO repeated this claim.

But many infectious-disease specialists, particularly those who were veterans of the 2003 SARS epidemic, were not convinced. Taiwan pushed to visit China. By Jan. 12, Chuang was en route to Wuhan, where he would spend two days with a group of experts from Hong Kong and Macao.

The group met with local officials the next day. The first red flag, Chuang recalled, was that their hosts briefed them verbally, without showing them epidemiological curves, or “epi curves,” that are essential to understanding outbreaks.

“They did not provide a PowerPoint, they did not provide any curves, so I knew they were reluctant to show us everything,” he said.

Then there were the cases. What the Chinese officials described were clusters in which not every case was directly linked to the market. This suggested that people were spreading the virus elsewhere.

The group pressed the officials for more epidemiological detail. “Most of the visitors tried to ask about human-to-human transmission, each one from a different angle,” Chuang said.

The Chinese officials kept saying there was no evidence of human-to-human transmission, Chuang said. Then a national official interjected, saying limited human-to-human transmission could not be excluded. “So, this is the real situation,” Chuang thought.

His suspicions were deepened the next day at Wuhan’s Jinyintan Hospital, where the group was taken to a “clean room” and shown patients on a monitor. The measures suggested that doctors were worried about visitors getting infected.

Chuang and the others pressed for case details, but the doctors were tight-lipped. He realized he would be going home without all the information he expected. “Probably they were not allowed to tell the truth,” he said.

Chuang returned to Taiwan and updated health officials. The next day, he outlined his findings to the press. Taiwan immediately upped its travel advisory, warning travelers to Wuhan to avoid crowded places and urging those returning from the city to inform their doctors if they developed symptoms.

It wasn’t until three days later, on Jan. 19, that the head of a Chinese government team confirmed human-to-human transmission. Also at that time, a regional WHO office tweeted that there was evidence of limited human-to-human transmission.

Taiwan was ready. On Jan. 20, a Taiwanese woman returned from Wuhan with a fever, cough and shortness of breath. Health officials knew exactly what to do: She was taken from the airport to a designated hospital by a quarantine officer and treated in an isolation room.

Her test came back positive. Health officials alerted the public and contacted 46 people from her flight, Taiwan’s CDC said in a detailed news release.

Later that day, the United States reported its first case — but did not raise the same alarm. In a Jan. 22 interview at the World Economic Forum in Davos, Switzerland, President Trump said everything was “totally under control.”

“It’s one person coming in from China. We have it under control,” he said. “It’s going to be just fine.”