Biden and Dr. Richard Besser, acting director of the Centers for Disease Control and Prevention, reinforced the government's stance on a border amid confirmation that the virus now has penetrated 11 states and there have been roughly a hundred school system closings.
President Barack Obama ruled out a border closing during his prime time televised news conference Wednesday night, likening such a move to "closing the barn door after the horses are out."
Biden told interviewers on the morning network news shows he sympathizes with parents worried about the spread of the disease in this country, but said that shutting down America's borders would be far more complicated - and would carry potentially great consequences - than simpler steps like closing schools and canceling or postponing public meetings.
The vice president said that in addition to stressing personal hygiene, people should focus prevention efforts on confined places, settings for opportunistic infection such as airplane cabins, malls and classrooms.
Biden also reiterated on Thursday the advice the administration has been eagerly dispensing: "A parent whose child's school is closed out of a precaution or because there's been a confirmed case of flu should not take child then to a day care center. They're going to have to take them home."
"And the hope is that the employers will be generous in terms of how they treat that employee's necessary action of taking that child home and not being at work," he said.
Besser earlier reported confirmed swine flu cases in 10 states, including 51 in New York, 16 in Texas and 14 in California. The CDC counted scattered cases in Kansas, Massachusetts, Michigan, Arizona, Indiana, Nevada and Ohio. State officials in Maine said laboratory tests had confirmed three cases in that state, not yet included in the CDC count.
"It is time for people to pay attention, for people to do planning and to understand what they can do to prevent the infection," he said.
"This is a period of great uncertainty," he acknowledged. "It's a situation that is evolving rapidly and we are trying to study the impact of school closures on control of this as they're taking place." Besser said officials want to ensure that "school closure is in fact decreasing risk of spread in a community and not taking children who would have been at school and sending them out to malls and other places."
Asked why the administration has not turned to thermal sensors to detect people with the fever, Besser said officials don't consider them effective, "especially for an inspection where you are able to transmit if you're infected the day before you have symptoms."
Biden was asked whether he would advise his own family against flying to Mexico and back on a commercial airliner.
"I would tell members of my family - and I have - that I wouldn't go anywhere in confined places now," he said. "It's not just going into Mexico. If you're any place in a confined aircraft and one person sneezes, it goes all the way through the aircraft."
Asked if the government was including this in its official health guidelines, Dr. Anthony Fauci, an infectious disease specialist with the National Institutes of Health, said no. He said the CDC "is not really at that point."
Fauci also said that U.S. public health experts would not be surprised if the World Health Organization soon declares a swine flu pandemic, saying "it's moving in that direction."
Schools aren't the only focus. In California, dozens of Marines were under quarantine to see if they'll develop illness after contact with a comrade confirmed to have the new flu.
U.S. scientists are racing to develop the key vaccine ingredient - a strain of the virus engineered to trigger the immune system. But they cautioned Wednesday that it would take several months before enough doses could roll off assembly lines for the necessary testing in human volunteers.
The U.S. has reported the only death outside Mexico - a Mexican toddler who visited Texas with his family.
Biden was interviewed on ABC's "Good Morning America," CBS's "The Early Show" and NBC's "Today" show and Besser appeared on ABC and CBS. Fauci was on the "Today" show.