Table 2.

Anti-HBs positive rates and GMCs of participants at 20–31 years after primary vaccination.

Time after vaccination	No. detected	No. positive	Positive rate (%)	GMC* (95%CI)
20	42	30	71.43	138.04 (77.63 ~ 251.18)
21	73	47	64.38	213.80 (138.04 ~ 338.84)
22	47	32	68.08	190.55 (104.71 ~ 346.74)
23	55	32	58.18	117.49 (66.07 ~ 213.80)
24	34	17	50.00	69.18 (28.84 ~ 162.18)
25	55	29	52.73	117.49 (66.07 ~ 204.17)
26	64	35	54.69	89.13 (56.23 ~ 158.49)
27	80	44	55.00	128.83 (79.43 ~ 208.93)
28	96	46	47.92	107.15 (74.13 ~ 154.88)
29	147	61	41.50	100.00 (69.18 ~ 141.25)
30	164	79	48.17	95.50 (69.18 ~ 141.25)
31	36	16	44.44	109.65 (52.48 ~ 223.87)
total	893	468	52.41	112.20 (97.72 ~ 128.82)

*GMC of the anti-HBs-positive participants