A tourist from New York at the Tijuana-San Diego border where thousands cross daily, told Agence France Presse that he debated whether to cross into Mexico.
"I'm from New York, came to California for holidays and I wanted to cross to Mexico. But 10 minutes ago, I received a call from my cousin trying to alert me not to cross," the man told AFP. "I'm not sure now. I don't know what the flu is. But in any case, I can go and come back."
But those who did travel across the borders gave reasons that defied the travel advisory in logic and in actions.
"The business owners near the bridges in South El Paso tell me a lot of people from Juarez are coming over to El Paso, although not necessarily to shop," Alonso Flores, operations director at the El Paso Central Business Association told The El Paso Times. "They feel safe here, and they can take off the [medical] masks. They're not allowed to mill around over there, so they're coming here to do that, hang out."
"This describes an interesting behavior that the CDC is worried about," said Schaffner. "Some experts think that by wearing the mask people will do things they otherwise wouldn't that would put them at risk."
Schaffner hopes people still wash their hands, avoid public places if they're sick and keep away from sick people, whether wearing a face mask or not.
Egypt officials slaughtered hundreds of thousands of pigs Wednesday in response to the news of a swine flu outbreak, although the country has yet to report a single case of swine flu, according to the Associated Press.
The World Health Organization specified that the swine flu virus cannot be transferred by the consumption of pork, but many abroad and in the United States continue to confuse that point.
Egypt is the only country in the world so far to order a mass pig slaughter in light of the swine flu and quickly fell under criticism for the decision.
Although pork is banned in several predominately Islamic countries, pigs in Egypt largely are owned by the 10 percent Coptic Christian minority population living amid a Muslim majority that does not eat pork for religious reasons.
At one large pig farming center just north of Cairo, scores of angry farmers blocked the street to prevent health ministry workers in trucks and bulldozers from coming in to slaughter the animals, according to the Associated Press. Some pelted the vehicles with rocks, and shattered windshields -- and the workers left without killing any pigs.
Schaffner says the association between pigs and the swine flu (H1N1-09) virus has more to do with a "laboratory anomaly" of the virus and how it developed than anything to do with what's happening between humans and pigs.
"There's no suggestion that there's active transmission from pigs to people at this time," he said.