H2 strain attenuated live hepatitis A vaccines: Protective efficacy in a hepatitis A outbreak

Table 1 Status of H2 strain vaccines vaccination in Fucheng county in May 1997

Towns	No. of villages	Whole population	Population aged 1-15	No. of trial villages	Vaccine group	Control group
Fucheng	79	50847	11815	28	1224	1457
Manhe	38	26958	6563	31	560	920
Gucheng	76	40083	8375	44	694	1087
Cuimiao	84	40818	8931	40	1155	1133
Matou	82	37005	8817	32	653	352
Xiakou	56	29030	7123	14	265	297
Wangji	58	21468	5607	32	431	525
Dabai	46	19154	4369	16	201	344
Jianqiao	39	17440	4437	8	196	109
Jiangfang	57	24200	5717	10	172	260
Total	615	307003	71754	255	5551	6485

Table 2 HA cases found during the first 9 mo in 1998

Months	First ten days	Second ten days	Last ten days	Total
January	1	0	0	1
February	1	3	3	7
March	2	3	0	5
April	5	0	4	9
May	46	154	48	248
June	26	13	3	42
July	3	9	3	15
August	3	3	2	8
September	0	1	0	1

Table 3 Age and sex distribution of HA cases found in Fucheng County during the HA outbreak in 1998

Age	Male	Female	Total
1	2	1	3
2	2	1	3
3	7	4	11
4	12	3	15
5	20	16	36
6	31	19	50
7	28	17	45
8	20	10	30
9	18	13	31
10	12	6	18
11	9	7	16
12-14	13	4	17
15-24	10	7	17
25-34	2	3	5
35-63	2	3	5
Total	188	114	302

Table 4 Results of serum IgM anti-HAV in 138 1-15 year old HA cases found in the HA outbreak in Fucheng, 1998

Days between HA attack and interview	No. of tested	Age (mean ± SD)	Positive
			No	%	S/CO (mean ± SD)
1-29	12	6.33 ± 2.57	12	100.00	10.33 ± 1.22
30-59	46	8.11 ± 2.39	44	95.65	7.12 ± 2.50
60-89	61	7.36 ± 2.52	49	80.33	5.09 ± 2.71
90-119	8	7.13 ± 1.25	7	87.50	2.80 ± 2.24
Total	127	7.52 ± 2.45	112	88.19	6.31 ± 3.04

Table 5 Incidence rates of the trial population in the 14 villages invested

Villages	Vaccine group			Control group
	No. of Subjects	No. of HA cases	Incidence rate	No. of Subjects	No. of HA cases	Incidence rate
Dongni	17	0	0.00	29	1	3.45
Dongyi	32	0	0.00	34	3	8.82
Fuzhuang	0	0	0.00	9	1	11.11
Gengzhuang	5	0	0.00	10	3	30.00
Gucheng	48	0	0.00	62	3	4.84
Haitun	19	0	0.00	20	1	5.00
Houxong	32	1	3.13	26	2	7.69
Lihui	35	0	0.00	27	1	3.70
Liqiao	48	0	0.00	23	2	8.70
Liuhui	16	0	0.00	26	1	3.85
Liunan	35	0	0.00	40	2	5.00
Mengzhuang	4	0	0.00	49	3	6.12
Qiansong	40	0	0.00	42	1	2.38
Dainan	25	0	0.00	22	1	4.55
Total	356	1	0.28	422	25	5.92

Table 6 Comparison between vaccine group and control group on HAV infection features

Groups	No. of Subjects	IgM anti-HAV (+)		Clinical HA cases		Subclinical infection		Novel infection		Clinical/subclinical ratio
		No.	%	No.	%	No.	%	No.	%
Vaccine	271	12	4.4	1	0.4	11	4.1	12	4.4	1:11
Control	314	39	12.4	21	6.7	21	6.7	42	13.4	1:1
Relative risk			2.8		18.1		1.7		3.0	6.0
95%CI			1.5-5.3		2.5-133.9		0.8-3.4		1.6-5.6	0.9-40.2
χ²			11.7		16.0		1.9		13.9
P value			< 0.001		< 0.001		> 0.5		< 0.001	< 0.01
Statistical method			M-H		M-H		M-H		M-H	Fisher