We don't have a secure border in a time of war. I doubt we are gonna get one now.
Naturally we need copious amounts of infected foreign nationals flooding our country.
Surely the U.S. military is capable of defending our own border with Mexico. There would be other benefits to closing down the border, such as demonstrating our will and our ability to stop illegal immigration. The world would take note. I don’t suggest a permanent closure.
Obama of course is not about to take strong action to defend our border, so it’s all academic.