"It's pretty hard to protect yourself from the flu when you are in a crowd," said ABC News' chief health and medical editor Dr. Richard Besser. "Sure, you can use hand sanitizer to clean your hands. But when the person next to you lets go with a big sneeze or a cough, you are sunk."
And it's not just the crowded events, according to Schaffner. "It's the travel to and from the events," he said, describing how packed airplanes and busy airports can teem with germs. "There's only so much you can do when you're in 13C and someone's sneezing in 13B. It's an unlucky row."
So while the weekend will be big, it's not worth risking the health of those around you, according to Besser.
"If you have a fever or you are just getting over the flu, stay home," he said. "I know it's hard to do when it's an event you've really been waiting for, but it's the right thing to do."