 But now with the virus in dairy herds in the U.S., it could be closer to becoming transmissible between humans. One scientist says it's like a pandemic unfolding in slow motion. And while the threat is low, that could change in a heartbeat. The Transportation Security Administration is expecting the next 10 days of summer to be some of the busiest travel days of the year. More than 28 million Americans predicted to take the skies.