FILE PHOTO: Passengers wearing masks, amid the health threat of novel coronavirus, arrive on a direct flight from China at…
FILE - Passengers wearing masks, amid the health threat of a novel coronavirus, arrive on a direct flight from China at Chicago's O'Hare Airport, Jan. 24, 2020.

The Trump administration's unprecedented move to bar entry to foreigners coming from China won't stop the new coronavirus from entering the United States, experts say, and it may do more harm than good. 

While the United States is following several countries in trying to wall itself off from the virus that has killed more than 400 people, scientists say travel bans are unlikely to work and impose serious logistical and economic problems. 

"You quickly see that we are on a slope that we're not sure how to get off," said epidemiologist Jennifer Nuzzo with the Johns Hopkins Center for Health Security, "the benefits of which are very much uncertain. Whereas the known harms are potentially quite certain." 

The presidential proclamation issued January 31 suspends entry for foreign nationals who have visited China in the 14 days before arriving in the United States. 

"We made an aggressive decision in front of an unprecedented threat," said Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases at the U.S. Centers for Disease Control and Prevention, at a press briefing Monday. 

Messonnier noted that the case count had shot up from 41 to 17,000 in a matter of weeks. 

"That is 17,000 cases with a novel coronavirus that the population doesn't have immunity to," she added, and for which health officials don't have all the information they want. 

Passengers on a tram wear facemasks in hopes of preventing the spreading coronavirus in Hong Kong, Feb, 3, 2020.

The virus is spreading rapidly across China, she added. Cases outside China are increasing, including person-to-person spread to patients who have not traveled to Wuhan, where the outbreak was first reported. 

"Strong measures now may blunt the impact of this virus on the United States," Messonnier said. 

‘No reason’ for ban 

But the World Health Organization disapproves. 

"There is no reason for measures that unnecessarily interfere with international travel and trade," WHO Director-General Tedros Adhanom Ghebreyesus told the organization's executive board on January 30, the day before the Trump administration announced the travel ban. 

China criticized the United States for having "unceasingly manufactured and spread panic," and for "imposing excessive restrictions contrary to WHO recommendations," said Foreign Ministry spokeswoman Hua Chunying. 

It's not an easy balance for health officials to strike, said University of North Carolina-Chapel Hill epidemiology professor Lisa Gralinski. 

"Are we having a reasoned response that's justified by the data? Are we also protecting our population from, in this case, a virus that we still know fairly little about?" she said. 

However, she added, "we don't have a lot of great data saying that these measures are very effective." 

Restrictions that some countries imposed during the severe acute respiratory syndrome outbreak in 2003 and the H1N1 influenza pandemic in 2009 did little to slow the spread of those diseases.

And China's severe restrictions on travel within and out of Wuhan and several other cities have not stopped the new coronavirus outbreak from spreading across the country. 

Already here 

Stopping a contagious respiratory virus at the border is just very hard to do, experts say. 

Travelers arrive at LAX Tom Bradley International Terminal wearing medical masks for protection against the novel coronavirus outbreak, Feb. 2, 2020, in Los Angeles.

“It is true that the fewer people who potentially carry the virus who come into an area, the less likelihood of further spread," said Emory University public health and law professor Polly Price, "but, of course, we already know it's in the United States." 

Health officials have identified 11 cases so far, and the CDC expects more. 

And barring foreigners from entering the United States won't stop the virus because U.S. citizens are no less likely to carry it, she noted. 

Though China has the most cases by far, it is just one of 24 countries that have reported infections, and scientists say the virus had likely been spreading for weeks before the Wuhan outbreak was reported. 

"There's still the very real possibility that there are many more cases out there, and we don't have a great sense of where they are in the world," Nuzzo at Johns Hopkins said. 

"It makes it difficult to prevent the introduction of cases if you don't have a great sense of where all the cases are," she added. 

As the number of infected countries increases, she added, "will we then prevent travelers from those other countries that are reporting cases?" 

Afghan health workers wearing protective gear speak with passengers who arrived from China during a screening process for coronavirus, at the Hamid Karzai International Airport in Kabul, Afghanistan, Feb. 3, 2020.

Negative consequences 

The travel ban can ultimately hurt the effort to fight the disease, experts say. 

If reporting infections means a country's citizens will be locked out of the United States, that country may decide not to report infections, making it much harder to contain the outbreak. 

"There's concern that punitive measures send a bad signal to the rest of the world that may have a chilling effect on transparency," Nuzzo said. 

Scientists need all the data they can get from China to better understand how the virus spreads and how likely patients are to die from it, she added. That information affects how public health officials work to contain it and limit the impact on the most vulnerable. 

Not to mention the fact that China manufactures many of the medicines and protective gear that the world needs to combat the outbreak. 

"We can't isolate ourselves from China without doing harm to ourselves," she said. 

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