On July 31, two days before Brantly was due to be evacuated (and almost a year before Trump began his campaign by descending down a gold escalator), Trump tweeted, “Ebola patient will be brought to the U.S. in a few days—now I know for sure that our leaders are incompetent. KEEP THEM OUT OF HERE!”

A day later he added, “Stop the EBOLA patients from entering the U.S. Treat them, at the highest level, over there. THE UNITED STATES HAS ENOUGH PROBLEMS!” And later that evening, “The U.S. cannot allow EBOLA infected people back. People that go to far away places to help out are great—but must suffer the consequences!”

The next day: “The fact that we are taking the Ebola patients, while others from the area are fleeing to the United States, is absolutely CRAZY—Stupid pols.” And also: “The U.S. must immediately stop all flights from EBOLA infected countries or the plague will start and spread inside our ‘borders.’ Act fast!”

Those tweets encapsulate many of the themes that have come to define Trump’s presidency: barriers and exclusion; fear of the “other”; cruelty toward those in need; and division between “us” and “them,” even when both are American citizens. And much like his later campaign rhetoric and rally speeches, these messages worked. “It was that tweet that created a level of anxiety in the country,” said Amy Pope, a White House counterterrorism official, in an interview with the journalist Reid Wilson. “That was a crystallizing moment.”

Needless to say, global health experts disagree with Trump’s sentiments. While travel bans might seem like a rational way of dealing with outbreaks, the evidence is very clear that they don’t work. Determined people always find a way to get across borders and health screenings are imperfect, especially in cases where symptoms appear only after a certain incubation period. Instead of stopping transmission, travel bans more likely force people to deliberately hide their symptoms or lie about their history. And most importantly, they stanch the flow of aid that is necessary for controlling an outbreak in a resource-poor location. Why would doctors travel to an epidemic zone if, as Trump demanded, they would be forbidden from returning if their health was in danger?

To be clear, if Trump had wielded presidential power at the time and had acted on his sentiments, Brantly and Writebol would be dead. Hence the gross hypocrisy of retweeting a celebration of Brantly’s successful return and treatment when he tried to oppose it.

Trump continued to opine on Ebola for the rest of 2015. When the Liberian man Thomas Eric Duncan was diagnosed with Ebola in Dallas, Trump tweeted that “IT WILL ONLY GET WORSE.” He repeatedly called for stopping all air traffic to and from the outbreak zone. He called Barack Obama a “psycho” for not enacting such a ban and “dumb” for deploying thousands of troops—a move that was important in stemming the outbreak. He spread misinformation about how contagious Ebola is and stoked fears that it could easily spread.