HHS Secretary Kathleen Sebelius

Although H1N1 activity continues to wane, federal health officials caution that there is no guarantee the worst is over.

“We have an ebbing second wave, but an uncertain future,” said Thomas Frieden, MD, director of the Centers for Disease Control and Prevention. “We don’t know how many cases there will be between now, which is traditionally the beginning of the flu season, and May, when flu season traditionally ends.”

Kathleen Sebelius, secretary of the US Department of Health and Human Services, said, “People are going to be traveling over the holidays, getting together with friends and family, and so there’s a lot of opportunity to spread the virus.”

With 99.5 million doses of H1N1 vaccine now available in the US, federal health officials are urging Americans to take advantage of the increased supply and get vaccinated as soon as possible.

Sebelius, who received her H1N1 vaccination Wednesday, said, “We have a chance to lessen the impact, or even prevent, a big third wave when flu season really hits and we need to seize that opportunity right now.”