Table 1.

Age-specific increased HBsAg prevalence reported in Hong Kong.^*

1st year college students (reference 31)
Born 1983–1988
Age (years)	Subject No	HBsAg+ No (%)	P value
≤18	324	3 (0.9)	<0.001
19	854	21 (2.5)
20	262	12 (4.6)
≥21	82	8 (9.8)
≥21-year-old, birth date
1982	38	5 (13.2)	N/A§
1983	33	4 (12.1)
1985	16	2 (12.5)
1986	9	1 (11.1)
Age (years) of teenage mothers (reference 6)
Born before and after 1984
≤16	118	3 (2.5)	0.004
17	223	6 (2.7)
18	421	37 (8.8)
19	724	58 (8.0)
Born after 1984
≤16	N/A	N/A (1.2)	0.008
17	N/A	N/A (1.5)
18	N/A	N/A (7.1)
19	N/A	N/A (8.3)

^*Hepatitis B vaccine was not available for infants born before 1983, but they received catch-up vaccination in 1998. Selective vaccination program (hepatitis B immunoglobulin at birth and a series of three doses vaccine) was given to infants born to HBsAg-positive mothers 1983–1988. Since November 1988, universal vaccination has been implemented to cover all neonates.

^§Detailed results were not available in the original articles.