The U.S. Centers for Disease Control and Prevention (CDC) said Monday it expects the (A)H1N1 influenza virus to continue to spread globally and become a pandemic, but it ruled out the need to mass-produce a vaccine. CDC acting director Richard Besser said the virus likely would spread within the United States and the rest of the world, reaching pandemic status, but he insisted there was no need to rush into mass production of a vaccine. “The decision doesn't need to be made now whether to manufacture a vaccine, and clearly it doesn't need to be made now about should people be vaccinated for next season,” Besser told reporters in Washington. One reason not to rush into vaccine production is the fact that the virus might mutate in the coming months—while the Northern Hemisphere enjoys a warm-weather pause from its influenza season—and then return in a more virulent form in the cooler autumn weather. Therefore, world health officials should closely watch how the swine-flu virus evolves in the Southern Hemisphere, which is now starting its winter flu season, Besser said. “There are a number of things you want to look at. One is, is this becoming a predominant strain while there are other strains circulating?” Besser said. “Here in the United States, this is happening at the very end of the flu season, when there aren't a lot of other flu viruses around and competing with it.” “What happens when it goes into countries where there are other flu viruses causing disease? What happens in terms of resistance? What happens in terms of subtle changes to the virus, and what impact could that have on a vaccine strategy?” Besser said.
