Some 90 million children worldwide age 5 and younger get the flu each year because they are not vaccinated, researchers in Scotland say. Harish Nair of the Center for Population Health Sciences at the Medical School at the University of Edinburgh in Scotland and colleagues reviewed 43 previous studies involving roughly 8 million children. The study, published in The Lancet, found of the 90 million children stricken with influenza, 20 million are also diagnosed with flu-related pneumonia and about 1 million are admitted to the hospital. The research also found flu-related pneumonia claimed the lives of up to 111,500 children in 2008 -- 99 percent of the deaths occurred in developing countries. Dr. Howard Koh, assistant secretary for health at the U.S. Department of Health and Human Services, said each year in the United States an estimated 5 percent to 20 percent of the population may be infected and more than 200,000 may be hospitalized during the flu season. Flu shots -- which are still available at healthcare providers and many drug store chains -- are recommended for everyone six months and older, Koh said. The vaccine is particularly important for those at the highest risk of complications from the flu, including young children, pregnant women, seniors and people with chronic health conditions such as asthma, diabetes and heart or lung disease, he said.