ATLANTA, May 6 (Reuters) - The U.S. public could become more vulnerable to a flu pandemic if complacency about the need for heightened vigilance sets in, health experts said on Wednesday.
Those concerns would escalate if the H1N1 virus that has killed two people in the United States and made 642 others sick mutates into a more virulent form by the start of the traditional flu season in the fall.
In all, there are 1,516 confirmed cases of the swine flu virus in 22 countries, according to the U.N. World Health Organization.
But in the United States fear about flu appears to have subsided since the epidemic came to public attention more than two weeks ago because many cases appear to be mild.
"The risk of complacency, or a sense that we have weathered this, is a serious one," said Stephen Redd, director of Influenza Coordination at the U.S. Centers for Disease Control and Prevention in Atlanta.
"What we are going to be looking very hard at over the months to come is what's happening in other parts of the world and really trying to understand whether we would be at risk for a resurgence in the fall," Redd said.
CDC officials say they walk a fine line between ramping up public warnings to encourage people to take precautions such as washing hands while not adopting an alarmist posture that could risk their authority as the epidemic persists.
In one small sign of waning public interest in the flu threat, nationally syndicated talk show host Neal Boortz told his audience recently that the issue of flu was getting "really overblown."