A dose-response evaluation of inactivated influenza vaccine given intranasally and intramuscularly to healthy young adults.

Epidemic influenza occurs annually throughout the world and is accompanied by excess morbidity and mortality. Increasing the antigen content and topical administration of vaccine are two strategies being explored to improve the immune responses to trivalent inactivated influenza vaccine (TIV). We conducted a randomized, double-blind, placebo-controlled trial to compare the immunogenicity and reactogenicity of intramuscular (IM), intranasal (IN), or combined IM and IN administration of a contemporary US vaccine formulation at escalating dosage levels in young healthy adults.

Safety of high doses of influenza vaccine and effect on antibody responses in elderly persons.

Background: Immune responses after influenza immunization are reduced in elderly individuals, the group at greatest risk for complications and death after influenza. Improved vaccines are needed to address this problem.

Methods: Ambulatory individuals 65 years and older (N = 202) were assigned randomly to receive a single intramuscular injection of the 2001-2002 formulation of trivalent inactivated influenza vaccine containing 15, 30, or 60 microg of hemagglutinin per strain (up to 180 microg total per dose) or placebo.