ABC News reported about 35,000 Americans have contracted the flu, according to the US Centers for Disease Control and Prevention.
Some 800,000 people are expected to travel to Washington, DC to attend Monday's presidential inauguration, ABC News said.
"Our advice for the inauguration is the same advice for a day-to-day basis," said Health and Human Services spokeswoman Elleen Kane. "Make sure you get the flu shot; if you cough or sneeze, do it into your elbow; wash your hands frequently and keep them away from your nose and mouth; and if you feel sick, stay home."
Organizers fear the flu might spread quickly since so many people from around the country and the world are traveling to the district and will descend on a small area.
CBS News reported that neither former President George H.W. Bush nor former President George W. Bush will attend President Barack Obama's second inauguration.
George H.W. Bush is currently recovering from bronchitis and was recently in the hospital.
Former Democratic Presidents Jimmy Carter and Bill Clinton will attend, CBS News confirmed.