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. 2021 Mar 19;13(7):9801–9819. doi: 10.18632/aging.202733

Figure 1.

Figure 1

Different influenza A/H1N1 antibody titers in old males and females after QIVs vaccination. Violin plots are shown for immune responses of influenza ((A) A/H1N1, (B) A/H3N2, (C) BYAM, (D) BVIC)-reactive antibody in subject sera before and after vaccination based on HAI assay, p-value <0.05 indicated statistical significance. The dotted line represents the threshold of protective antibody titer ≥40 against each influenza vaccine strain.