Serum antibody response to homologous (TK/OR/71 (H7N3)) and heterologous (CK/NJ/02 (H7N2)) strains at 4 and 5 weeks of age.

(A) Homologous HI titers at 4 weeks of age. (B) Homologous HI titers at 5 weeks of age. (C) Heterologous HI titers at 4 weeks of age. (D) Heterologous HI titers at 5 weeks of age. Four weeks of age corresponded with 4 wpv for 1d IIV and 1d LAIV; 1 wpv for 3w LAIV and 3w IIV. Five weeks of age corresponded with 5 wpv for 1d IIV and 1d LAIV; 2 wpv for 3w LAIV and 3w IIV. The arrangement of groups highlights the synergy of LAIV priming and IIV boosting—LAIV-IIV is placed in the middle while other LAIV and IIV vaccinations are placed on the left and right, respectively. The individual and median HI titers are illustrated as symbols and horizontal lines, respectively. Different letters inside the plot indicate statistical significance among groups (p<0.05).