As the threat of the coronavirus in the US grew and markets reeled amid growing uncertainty, Donald Trump on Tuesday promoted one of his signature policy proposals. “We need the Wall more than ever!” he tweeted.

Trump has sought to downplay the severity of the public health crisis. And he has capitalized on the panic and disruption in some American communities to push for many of his longstanding campaign promises, including stricter border security, travel bans, tax cuts and lower interest rates.

Trump’s response to the coronavirus threat has been consistent with his reaction to everything else, said Max Skidmore, a professor of political science at the University of Missouri-Kansas City and author of Presidents, Politics, and Pandemics. “He has a certain agenda and is adapting reality to confirm to that,” Skidmore told the Guardian.

In past weeks, Trump has repeatedly offered a fortified border wall as a solution to contain the disease. “The Democrat policy of open borders is a direct threat to the health and wellbeing of all Americans,” he said at a rally in South Carolina. “Now, you see it with the coronavirus.”

But the number of reported cases in Mexico is far lower than the number of cases in the US and there is no evidence that migrants traveling across the border have transmitted coronavirus to anyone in the US. Testifying before House lawmakers, Robert Redfield, the director of the Centers for Disease Control and Prevention (CDC), denied that structural barriers at the border would help mitigate the spread of Covid-19. And public health experts have warned that a focus on the border wall is not only futile but also counterproductive.

“People always find a way around walls,” said Amy Fairchild, dean of the college of public health at Ohio State University. And harsher enforcement at the border would keep migrants who might be infected from getting tested and seeking treatment, according to Fairchild.

Trump, who has long fought to restrict travel from a number of countries, many with large Muslim populations, has also leaned into the idea of travel bans as a response to the coronavirus threat.

The administration has expanded its travel restrictions on Iran and issued “do not travel” warnings to areas in Italy and South Korea, in addition to temporarily denying entry to foreign nationals who have visited China in the 14 days prior to their arrival to the US.

But public health officials and experts have warned there are downsides to that approach. Limiting movement between the US and areas where many people have been infected can slow the spread of disease. But severe restrictions “can have the effect of increasing fear and stigma, with little public health benefit”, said the World Health Organization (WHO) director, Tedros Adhanom Ghebreyesus, during a briefing to the United Nations executive board this week. “We reiterate our call to all countries not to impose restrictions that unnecessarily interfere with international travel and trade.”

But Trump has favored isolationist policies despite the warnings, boasting at a Fox News town hall last week that he had “closed down the borders” to China and other affected countries. It made sense, Skidmore said, considering that “President Trump is not comfortable with alliances and international cooperation”.

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The president and his surrogates have also taken the opportunity to promote his campaign promises to boost manufacturing in the US. “The coronavirus shows the importance of bringing all of that manufacturing back to America, and we will have that started,” he said as he met with representatives from pharmaceutical companies last week.

In January, Trump’s commerce secretary, Wilbur Ross, went as far as saying that coronavirus in China would “help to accelerate the return of jobs to North America”.

But Trump’s isolationist tendencies and his resistance to working with the WHO and other countries could slow down the US’s ability to develop a vaccine and treatment for Covid-19, Skidmore noted. One reason widespread testing for coronavirus was delayed was that federal agencies rejected the WHO’s test guidelines and instead set out to create a more complicated test that was ultimately faulty, according to an investigation by ProPublica.

Trump’s preoccupation with tax cuts and rate cuts in order to steady the reeling stock market was another example of the president focusing on his own political agenda, and in the process missing the forest for the trees, according to Skidmore. As the markets became volatile, Trump finally got what he had long been pushing for: lower interest rates.

The Federal Reserve made emergency interest rate cuts, and Trump has been pressuring the Fed to cut them down further. The president also met with Republican senators today to pitch them on a payroll tax cut which would benefit mostly affluent workers, and have the effect of undermining Medicare and social security – institutions that Trump has long sought to cut back.

And while some sort of stimulus package could help rally the markets, it doesn’t address the issues of disrupted supply chains and quarantined workers, canceled classes and conferences and slumping travel and tourism. “At the moment, there’s no real consideration given to pay for the people who are quarantined [and keep them from] from suffering financially,” Skidmore said. Moreover, it’s unclear how, exactly, the administration plans to coordinate access to free testing, and eventually a free vaccine.

Trump has ratified an $8.3bn emergency coronavirus funding package, “which, yes, is going to help in terms of vaccine development”, said Fairchild. But the president’s proposed 10-year budget, which signals huge cuts to the CDC, National Institutes of Health and other agencies, doesn’t bode well for the containment of coronavirus or other disease threats in the future. “With these policies, we’re going to continue to be susceptible to outbreaks,” she said.