Effectiveness of self-financed rotavirus vaccination in Ise City, Japan

Figures & data

Table 1. Age distribution of children hospitalized for rotavirus or non-rotavirus acute gastroenteritis

Diagnosis	Age (month)	Pre-rotavirus vaccination years						Self-financed rotavirus vaccination years
		2006/2007	2007/2008	2008/2009	2009/2010	2010/2011	Subtotal	2011/2012	2012/2013	2013/2014	2014/2015	2015/2016	2016/2017	2017/2018	Subtotal
Rotavirus AGE	0–11	4	1	5	1	6	17	5	5	1	0	0	0	0	11
	12–23	5	5	11	7	10	38	6	15	1	0	0	0	1	23
	24–35	3	2	6	2	3	16	1	9	2	0	2	2	0	16
	36–47	4	2	4	3	6	19	2	6	1	1	2	1	0	13
	48–59	0	0	0	0	1	1	1	5	1	0	2	1	1	11
	Subtotal * (male)	16 (14)	10 (7)	26 (14)	13 (10)	26 (8)	91 (53)	15 (11)	40 (19)	6 (1)	1 (0)	6 (3)	4 (1)	2 (0)	74 (35)
Non-rotavirus AGE	0–11	14	4	8	6	11	43	5	13	4	3	6	7	5	43
	12–23	16	21	14	11	12	74	9	13	1	8	5	4	6	46
	24–35	11	9	5	5	5	35	3	3	3	2	5	3	8	27
	36–47	7	11	4	1	5	28	8	5	3	4	3	2	2	27
	48–59	6	7	7	5	4	29	7	4	8	2	1	4	1	27
	Subtotal * (male)	54 (42)	52 (33)	38 (22)	28 (17)	37 (23)	209 (137)	32 (18)	38 (23)	19 (11)	19 (14)	20 (13)	20 (11)	22 (22)	170 (112)
Total number of AGE patients (male) *		70 (56)	62 (40)	64 (36)	41 (27)	63 (31)	300 (190)	47 (29)	78 (42)	25 (12)	20 (14)	26 (16)	24 (12)	24 (22)	244 (147)

AGE, acute gastroenteritis; * The numbers in parentheses indicate the number of male patients.

Table 2. Population-based figures of hospitalizations for rotavirus acute gastroenteritis less than 5 years

Reference	Season	Population of <5 years	No. of hospitalizations	Hospitalization rate (/1000 person-years)	95% CI	p
Pre-rotavirus vaccination years	2006/2007-2010/2011	26715	91	3.4	2.7–42	-
Self-financed rotavirus vaccination years	2011/2012	5185	15	2.9	1.6–4.8	.648
	2012/2013	5106	40	7.8	5.6–10.7	< .001
	2013/2014	5014	6	1.2	0.4–2.6	.014
	2014/2015	4977	1	0.2	0.0–1.1	<.001
	2015/2016	4795	6	1.3	0.5–2.7	.019
	2016/2017	4724	4	0.8	0.2–2.2	.005
	2017/2018	4514	2	0.4	0.1–1.6	.001
	Overall	34315	74	2.2	1.7–2.7	.004

CI, confidence interval; *, The incidence rates of rotavirus AGE in the pre-rotavirus vaccination years and self-financed rotavirus vaccination years were compared by Fisher’s exact test. The 2012/2013 season showed the highest incidence rate throughout the seasons.; #, Exact Poisson test.

Figure 1. Distribution of rotavirus acute gastroenteritis cases by month of admission in patients under 5 years of age (2006/2007–2017/2018 seasons). The pre-rotavirus vaccination years are indicated by small circles, and the self-financed rotavirus vaccination years are indicated by squares.

Figure 2. Forecast of hospitalization incidence rate for rotavirus acute gastroenteritis in patients under 5 years of age by time-series analysis. R1, monovalent vaccine; R5, pentavalent vaccine. Blue line shows observed incidence rates, and red line shows forecasted incidence rates obtained by the Holt-Winters additive seasonal smoothing method.

Table 3. Rotavirus vaccine effectiveness estimates against rotavirus acute gastroenteritis hospitalization in post-vaccine period

Year of birth	Vaccine coverage %	Vaccinated		Unvaccinated		Vaccine effectiveness (95% CI)
		No. of hospitalizations	No. of children	No. of hospitalizations	No. of children	Direct %	Indirect %	Total %	Overall %
2012	27	1	246	11	661	76	28	82	43
2013	51	3	541	4	529	27	67	76	72
2014	61	1	569	0	362	-	100	92	95
2015	69	0	654	1	298	100	86	100	95
2016	75	0	667	0	223	-	100	100	100
2017	76	0	621	1	199	100	78	100	95
2018	82	0	682	0	150	-	100	100	100
Overall	62	5	3980	17	2422	82 (52–93)	70 (51–82)	95 (87–98)	86 (77–91)

Of 6161 children born between 2006 and 2011 before the introduction of the vaccine, there were 143 hospitalizations between 2007 and 2018. VE is calculated by the formula (1 – RR) × 100. The formula for calculating VE has been given in the “evaluation of VE” section of the manuscript. CI, confidential interval.