Table 1. Chi-square test of factors influencing anti-HBs titers after primary immunization with 5 μg HB vaccines, Guangdong, China 2006.

	Total	Anti-HBs titer < 100mIUml-l		RR(95%CI)
		n	%
Infant months
7	1789	572	32	0.89(0.52–1.5)
8	25	9	36
Infant Sex
Male	1006	314	31	0.94(0.83–1.08)
Female	808	267	33
LBW
Yes	62	31	50	1.6(1.2–2.0)
No	1728	548	32
Premature
Yes	69	25	36	1.1(0.82–1.6)
No	1734	553	32
Mother HBsAg-positive
Yes	118	40	34	1.0(0.78–1.3)
No	1316	438	33
Mother HBeAg-positive
Yes	34	12	35	1.1(0.66–1.7)
No	1372	461	34