There is usually very close agreement between vaccine package inserts and ACIP statements. The Food and Drug Administration (FDA) must approve the package insert, and requires documentation for all data and recommendations made in the insert. Occasionally, ACIP may use different data to formulate its recommendations, or try to add flexibility to its recommendations, which results in wording different than in the package insert. ACIP sometimes makes recommendations based on expert opinion and public health considerations. Published recommendations of ACIP should be considered equally as authoritative as those on the package insert.