Schoolchildren could be first in line for swine flu vaccine this fall - and schools are being put on notice that they might even be turned into shot clinics. Health and Human Services Secretary Kathleen Sebelius said Tuesday she is urging school superintendents around the country to spend the summer preparing for that possibility, if the government goes ahead with mass vaccinations. If you think about vaccinating kids, schools are the logical place," Sebelius told The Associated Press. No decision has been made yet on whether and how to vaccinate millions of Americans against the new flu strain that the World Health Organization last week formally dubbed a pandemic, meaning it now is circulating the globe unchecked. But the U.S. is pouring money into development of a vaccine in anticipation of giving at least some people the shots. While swine flu doesn't yet seem any more lethal than the regular flu that each winter kills 36,000 people in the U.S. alone, scientists fear it may morph into a more dangerous type. Even in its current form, the WHO says about half of the more than 160 people worldwide killed by swine flu so far were previously young and healthy. If that trend continues, "the target may be school-age children as a first priority" for vaccination, Sebelius said Tuesday. "That's being watched carefully." The last mass vaccination against a different swine flu, in the U.S. in 1976, was marred by reports of a paralyzing side effect - for a feared outbreak that never happened. The secretary said: "The worst of all worlds is to have the vaccine cause more damage than the flu potential."