Table 1. Cross-reactive antibody responses against influenza A (H3N2) viruses of human sera collected in China.

Age group (year)	Antigen	%HI titer ≥40 (95% CI*)	%NI titer ≥10 (95% CI*)	%NT titer ≥40 for children or ≥80 for adults (95% CI*)
≤10, n=100	BJ/1230/16 (human)	15.0 (7.9–22.1)	26.0 (17.4–34.6)	14.0 (7.2–20.8)
	Cn/BJ/38/16	1.0 (0–2.9)	2.0 (0–4.7)	1.0 (0–2.9)
	Cn/FJ/1109/18	1.0 (0–2.9)	2.0 (0–4.7)	1.0 (0–2.9)
	Cn/GZ/011/19	2.0 (0–4.7)	3.0 (0–6.3)	2.0 (0–4.7)
25–53, n=100	BJ/1230/16 (human)	8.0 (2.7–13.3)	12.0 (5.6–18.4)	6.0 (1.4–10.6)
	Cn/BJ/38/16	0	1.0 (0–2.9)	0
	Cn/FJ/1109/18	1.0 (0–2.9)	2.0 (0–4.7)	0
	Cn/GZ/011/19	1.0 (0–2.9)	1.0 (0–2.9)	0
≥60, n=100	BJ/1230/16 (human)	5.0 (0.7–9.3)	12.0 (5.6–18.4)	4.0 (0.2–7.8)
	Cn/BJ/38/16	0	1.0 (0–2.9)	0
	Cn/FJ/1109/18	1.0 (0–2.9)	1.0 (0–2.9)	0
	Cn/GZ/011/19	1.0 (0–2.9)	2.0 (0–4.7)	0

^*Confidence interval.