430,000 People Have Traveled From China to U.S. Since Coronavirus Surfaced

Since Chinese officials disclosed the outbreak of a mysterious pneumonialike illness to international health officials on New Year’s Eve, at least 430,000 people have arrived in the United States on direct flights from China, including nearly 40,000 in the two months after President Trump imposed restrictions on such travel, according to an analysis of data collected in both countries.

The bulk of the passengers, who were of multiple nationalities, arrived in January, at airports in Los Angeles, San Francisco, New York, Chicago, Seattle, Newark and Detroit. Thousands of them flew directly from Wuhan, the center of the coronavirus outbreak, as American public health officials were only beginning to assess the risks to the United States.

Flights continued this past week, the data show, with passengers traveling from Beijing to Los Angeles, San Francisco and New York, under rules that exempt Americans and some others from the clampdown that took effect on Feb. 2. In all, 279 flights from China have arrived in the United States since then, and screening procedures have been uneven, interviews show.

Mr. Trump has repeatedly suggested that his travel measures impeded the virus’s spread in the United States. “I do think we were very early, but I also think that we were very smart, because we stopped China,” he said at a briefing on Tuesday, adding, “That was probably the biggest decision we made so far.” Last month, he said, “We’re the ones that kept China out of here.”

But the analysis of the flight and other data by The New York Times shows the travel measures, however effective, may have come too late to have “kept China out,” particularly in light of recent statements from health officials that as many as 25 percent of people infected with the virus may never show symptoms. Many infectious-disease experts suspect that the virus had been spreading undetected for weeks after the first American case was confirmed, in Washington State, on Jan. 20, and that it had continued to be introduced. In fact, no one knows when the virus first arrived in the United States.

During the first half of January, when Chinese officials were underplaying the severity of the outbreak, no travelers from China were screened for potential exposure to the virus. Health screening began in mid-January, but only for a number of travelers who had been in Wuhan and only at the airports in Los Angeles, San Francisco and New York. By that time, about 4,000 people had already entered the United States directly from Wuhan, according to VariFlight, an aviation data company based in China. The measures were expanded to all passengers from China two weeks later.

In a statement on Friday, Hogan Gidley, a White House spokesman, described Mr. Trump’s travel restrictions as a “bold decisive action which medical professionals say will prove to have saved countless lives.” The policy took effect, he said, at a time when the global health community did not yet “know the level of transmission or asymptomatic spread.”

Trump administration officials have also said they received significant pushback about imposing the restrictions even when they did. At the time, the World Health Organization was not recommending travel restrictions, Chinese officials rebuffed them and some scientists questioned whether curtailing travel would do any good. Some Democrats in Congress said they could lead to discrimination.

In interviews, multiple travelers who arrived after the screening was expanded said they received only passing scrutiny, with minimal follow-up.

“I was surprised at how lax the whole process was,” said Andrew Wu, 31, who landed at Los Angeles International Airport on a flight from Beijing on March 10. “The guy I spoke to read down a list of questions, and he didn’t seem interested in checking out anything.”