Table 2.

Comparison of the positive seroprotection rate 1 month and 8 years later with different schedules.

Groupa	N	n1	PSR1 (%)	χ2	P	N	n2	PSR2 (%)	χ2	P
Group I	241		77.6	23.670	0.000	104	71	68.3	8.873	0.012
Group II	290		86.9c			45	26	57.8
Group III	240		92.9b			93	44	47.3b

N, Total number; n1, number of positive seroprotection 1 month after vaccination; PSR, positive seroprotection rate; n2, number of positive seroprotection 8 years later.

The chi-square test (after Bonferroni adjustment) was used for multiple comparisonsof the PSR among the three groups.

^aParticipants were assigned to one of the three groups depending on the vaccination schedule chosen. Group I: vaccinated at 0–1–3 months; group II: vaccinated at 0–1–6 months; group III: vaccinated at 0–1–12 months.

^bP < 0.05, compared with Group I.

^cP < 0.05, compared with Group I.