U.S. health officials have begun an aggressive influenza vaccine promotion campaign, fearing that many people have forgotten how sick the flu can make them, and worrying about a possible re-emergence of severe acute respiratory syndrome (SARS). The flu and SARS have similar early symptoms. The Centers for Disease Control and Prevention recommends flu vaccinations especially for those demographic groups at most risk of developing serious illness, including health care workers and the elderly, but it hopes that even people not in those groups will get vaccinated as well. There are no anticipated flu vaccine shortages this year, and there is a new inhaled vaccine for healthy adults. Some health experts stress that the difference between flu and SARS must be made clear, lest people believe that the vaccine will prevent SARS, and others note that people must be told that even with the flu vaccine they can still get the illness or other respiratory illnesses.