3.3 Age-based Analysis of RV Infections
In this investigation, RV-positive patients were categorized into four age groups in alignment with the traditional living habits of Chinese children: 0-1 years (Group 1), 1-3 years (Group 2), 3-7 years (Group 3), and 7-18 years (Group 4). Between 2021 and 2023, in terms of age distribution of patients with RV infection, the highest proportion of RV patients was observed in the 0-1y group, accounting for 36.12% (1532/4242). This was followed by the 3-7y group had a prevalence of 30.46% (1292/4242). The 1-3 year group accounted for 25.93% (1100/4242), while the remaining 7.50% (318/4242) were in the 7-18y group (Table 3). A year-on-year analysis revealed that the proportion of RV infections within the 0-1 years group accounted for 39.5% and 40.24% of total annual positive cases in 2021 and 2022, respectively, but decreased to 31.5% in 2023. Statistical analysis indicated a significant variance in these proportions (χ² = 32.24, p< 0.001). For children aged 1-3 years, the proportion of RV infections in the total annual infection decreased from 31.91% in 2021 to 20.12% in 2022, with an increase to 25.91% in 2023. The chi-square test indicated that these variations were significant (χ² = 42.15,p < 0.001). Within the 3-7 year age group, the proportion of RV infections in the total annual infection increased exhibited an increase from 25.39% in 2021 to 32.85% in 2022, with a further reduction to 30.03% in 2023. The chi-square test suggested statistical significance (χ² = 19.35, p < 0.001). The 7-18 year age group exhibited an increase from 3.13% in 2021 to 6.80% in 2022, with a further rise to 10.55% in 2023. Statistical analysis confirmed the significance of this trend (χ² = 58.26, p< 0.001) (Table 3).
Regarding the infection rates of RV among inpatients with ARTIs across various age groups, this study identifies significant fluctuations in the incidence rates among different groups. Between 2021 and 2023, the most pronounced incidence of RV-positive cases was observed within the 0-1 year age group, which accounted for 24.94% (1532 out of 6142) of all cases. This was followed by the 1-3 year age group, accounting for 21.55% (1100 out of 5105). The 3-7 year age group exhibited a prevalence of 21.30% (1292 out of 6066), while the 7-18 year age group comprised 13.43% (318 out of 2367) of cases. The RV infection rates were significantly different between the age groups (χ² = 134.24,p <0.001). As shown in figure 2, in the 0-1 year age group, a notable fluctuation in incidence rates was observed in year-on-year analysis, rising from 22.25% in 2021 to 33.55% in 2022, followed by a decrease to 22.47% in 2023. These changes were found to be statistically significant (χ² = 72.57, p < 0.001). For children aged 1-3 years, a decrement in the incidence rate from 26.05% in 2021 to 18.16% in 2022 was noted, with a slightly increase to 20.74% in 2023. The chi-square test indicated that these variations were significant (χ² = 26.64, p < 0.001). Within the 3-7 year age group, the incidence rate exhibited a decline from 26.14% in 2021 to 21.39% in 2022, with a further reduction to 19.52% in 2023. The chi-square test yielded a value of 21.55, suggesting statistical significance (χ² = 21.55, p < 0.001). The 7-18 year age group witnessed a marked decrease in the incidence rate from 24% in 2021 to 11.43% in 2022, with a slight rise to 13.32% in 2023. Statistical analysis confirmed the significance of this trend (χ² = 16.84, p < 0.001). Notably, the majority of RV cases occurred in toddlers aged under three years (Table 2).