(CNN) -- Though the United States has not issued any travel warnings related to the swine flu outbreak in Mexico, major U.S. airlines are waiving fees for passengers who want to change their tickets to Mexico.
Continental Airlines said Sunday that it will allow passengers to reschedule or reroute their travel without charging them a fee -- if they are scheduled to fly to Mexico through May 6.
American Airlines is allowing customers to change their flights without penalty if they are flying to Mexico through May 6.
United Airlines is issuing a travel waiver to customers traveling to Mexico City through April 30.
And Delta Air Lines is waiving the change fee for customers traveling to Mexico through May 4.
On Saturday, US Airways said it would allow passengers to change plans if they wanted to because of the outbreak.
US Airways is not asking people to avoid Mexico, but wants to offer them flexibility if "they don't feel comfortable," spokeswoman Michelle Mohr said.
The U.S. Air Transport Association is in regular contact with the Centers for Disease Control and Prevention, said Katherine Andrus, an attorney for the airline trade association.
Airlines are following their own procedures in watching for sick passengers and crews have standard procedures for dealing with them, Andrus said. Any onboard communicable disease incidents must be reported to the CDC, she said.
"This is a time for appropriate precautions but not panic," she said.