The potential for widespread human disease due to the H3N2v influenza viruses is considerable. Infection with these viruses would most likely impact young children. This study will evaluate the safety and immunogenicity of the H3N2v MN 2010/AA ca live attenuated influenza vaccine (H3N2v LAIV) in healthy children and adults, 6 to 26 years old.~The study will enroll participants sequentially in four groups: Group 1 will include H3N2v seronegative adults ages 18-26 years; Group 2 will include H3N2v seropositive adolescents ages 13-17 years; Group 3 will include H3N2v seronegative adolescents ages 13-17 years; and Group 4 will include children ages 6 to 12 years, who will not be screened for H3N2v serostatus.~At study entry (Day 0), participants in Group 1 will receive one dose of H3N2v LAIV. Participants in Groups 2, 3, and 4 will be randomly assigned to receive two doses of either H3N2v LAIV or placebo, receiving the first dose on Day 0 and the second dose on Day 28. On Day 84, all participants will receive one dose of H3N2v IIV (an inactivated booster vaccine).~Participants will attend several additional study visits through Day 180. These visits may include a physical examination; respiratory examination; and collection of blood, urine, or nasal fluids.
This study will evaluate the safety and immunogenicity of the H3N2v MN 2010/AA ca live attenuated influenza vaccine (H3N2v LAIV) in healthy children and adults, 6 to 26 years old.