WASHINGTON (CNN) - An H1N1 flu vaccine should be ready in October if a strain now moving through the southern hemisphere heads north for the fall and winter, Health and Human Services Secretary Kathleen Sebelius said Sunday.
Speaking on NBC's "Meet the Press," Sebelius said the vaccine still must undergo clinical trials to ensure it is both effective against the virus and safe for people.
"We're on track to have a vaccine ready by mid-October," she said.
The pandemic was first detected in Mexico earlier this year before moving to the United States, Europe and other nations in the northern hemisphere. The virus is now more prevalent in the southern hemisphere, where is it is winter.
Flu is typically more active and prevalent during the fall and winter.
The World Health Organization raised the worldwide pandemic alert level June 11 to phase 6, the highest designation. The most recent WHO figures, from early July, listed 170 flu fatalities in the United States, along with 119 in Mexico and 60 in Argentina.
However, the figures have risen since then. WHO stopped listing national totals after July 6 because, the organization said, "the increasing number of cases in many countries with sustained community transmission is making it extremely difficult, if not impossible, for countries to try and confirm them through laboratory testing."