WASHINGTON (CNN) - President Barack Obama said Friday that while the swine flu virus does not appear to be as dangerous as initially thought, Americans should not let down their guard.
"The (H1N1) virus may not have been as virulent as we once feared, but we're not out of the woods yet," Obama said.
The president said Americans should continue to take basic precautions such as frequently washing their hands. He also said the country should prepare for a particularly tough flu season this fall.
Obama made his remarks during a brief surprise appearance at a town hall-style event for the Latino community on the H1N1 virus, as swine flu is officially called. The event, conducted mostly in Spanish, was hosted by Labor Secretary Hilda Solis.
The number of confirmed H1N1 flu cases in the United States has nearly doubled to 1,639 cases in 43 states over the last day, the Centers for Disease Control and Prevention reported on its Web site Friday.
Thursday, the CDC reported it had confirmed 896 cases in 41 states.
Two people have died in the United States in connection with the virus.