Role of rotavirus vaccination on G9P[8] rotavirus strain during a seasonal outbreak in Japan

Figures & data

Figure 1. Year-long detection RV-positive cases. Percentages among children visited the month with AGE (number, n, has been shown) have been demonstrated

Table 1. Characteristics of RV outbreak

Characteristics		G9P[8]I2-RV-positive AGE (n = 29)	Other RV-positive AGE (n = 4)	RV-negative AGE (n = 45)
Age group: n (%)
	<25 m	12 (15.4*)	4 (5.1)	31 (39.7)
	25–36 m	12 (15.4)**	0 (0)	7 (9.0)
	>36 m	5 (6.4)	0 (0)	7 (9.0)
Sex: n (%)
	Male	17 (21.8)	1 (1.3)	31 (39.7)
	Female	12 (15.4)	3 (3.8)	14 (17.9)
Vesikari Score (median, Q1-Q3)		7 (6–9)***	5.5 (5–6)	5 (4–7)
Severity n (%)
	Mild	9 (11.5)	4 (5.1)	31 (39.7)
	Moderate-Severe	20 (25.6)****	0 (0)	14 (17.9)
Vaccine Status
	Vaccinated	4 (5.1)	1 (1.3)	16 (20.5)
	Unvaccinated	25 (32.1)*****	3 (3.8)	29 (37.2)

*Percentage among 78 children has been shown. Since the sample number of other RV-positive AGE was very small, we omitted this group from statistical analysis.

**Number of 25–36 m age group children (compare to the number in <25 m age group), in G9P[8]I2-RV infection was significantly higher than that in RV-negative AGE (P = .009).

*** Severity score in G9P[8]I2-RV infection was significantly higher than that of RV-negative AGE (P = .00).

**** Moderate-severe infection in G9P[8]I2-RV infection was significantly higher than that in RV-negative AGE (P = .002).

***** Number of Unvaccinated children in G9P[8]I2-RV infection was significantly higher than that in RV-negative AGE (P = .04).

Table 2. Vaccine effectiveness (VE) determined at different disease severity

	RV-positiveAGE	Vaccinated (%)	RV-negativeAGE	Vaccinated (%)	Adjusted VE (95% CI)	P-value
All RVA strains	33	5 (15.2%)	45	16 (35.6%)	69.7% (2.5% to 90.6%)	.045*
Severity ≥7	20	2 (10.0%)	45	16 (35.6%)	80.7% (3% to 96.2%)	.046*
Severity ≥11	4	0 (0%)	45	16 (35.6%)	100%^a	.998
G9P[8]I2-RV strain	29	4 (13.8%)	45	16 (35.6%)	71.8% (1% to 92%)	.048*

VE (vaccine effectiveness) was determined against RV infection (Severity Score ≥1, ≥7 and ≥11) by (1-adjusted OR) X100. OR adjusted for age with 95% CI (confidence interval) and probability (P)-value was determined by binary logistic regression. Asterisks indicate statistically significant values.

^a95% CI could not be calculated because 0 was in one cell.

Table 3. Differences in Vesikari scores by vaccination status

		n	Mild (<7)	Moderate (7–10)	Severe (≧11)	MedianVesikari Score (Q1,Q3)	P
RV-positive group (n = 33)	Vaccinated	5	3 (60%)	2 (40%)	0 (0%)	5 (5, 7)	.047*
	Unvaccinated	28	10 (35.7%)	14 (50.5%)	4 (14.3%)	7 (6, 9)
RV-negative group (n = 130)	Vaccinated	39	29 (76.3%)	8 (21.1%)	1 (2.6%)	5 (4, 6)	.168
	Unvaccinated	91	76 (82.6%)	12 (13%)	4 (4.3%)	5 (4, 6)

P-values were determined by comparing median Vesikari scores of two groups by Mann–Whitney U tests.