Some 2 billion people worldwide could be infected by swine flu if the current outbreak turns into a pandemic, the World Health Organization said Thursday.
"If we do move into a pandemic, then our expectation is that we will see a large number of people infected worldwide," WHO flu chief Keiji Fukuda said. "If you look at past pandemics, it would be a reasonable estimate to say perhaps a third of the world's population would get infected with this virus."
Meanwhile, it appears that many major cities are mellowing after the flu scare, which immobilized some parts of the world. For example, in Mexico, which has experienced the most cases, high schools and universities opened for the first time in two weeks, and top health officials there insisted the epidemic is on the decline. All students were checked for swine flu symptoms and some were sent home. But, says Fukuda, his organization cannot look into the future.
Even with a mild flu, "from the global perspective there are still very large numbers of people who could develop pneumonia, require respirators, who could die," Fukuda said. Much depends on the overall health condition of particular region, he said, noting that oftentimes younger people in the Southern Hemisphere are more vulnerable because of malnourishment, war, HIV infections and other factors. This means a mild outbreak in wealthier countries can be "quite severe in its impact in the developing world," he said.
"We expect this kind of event to unfold over weeks and months. Pandemics don't occur in a couple of days. When we go back and we look at history, we're often looking at a one-year period. Really if you look over a two-period that is really the period in which you see an increase in the number of illnesses and deaths during a pandemic influenza."