3.2 Seasonal and age distribution of RVA-infected children
Although RVA infection was prevalent in all seasons from May 2020 to December 2022, a different monthly distribution was observed in different years. The infection rate of RVA increased rapidly and peaked in September in 2020 (41.7%, 10/24). In 2021, RVA infection was detected mainly in winter and spring, peaking in March (37.9%, 11/29) and May (37.8%, 48/127). In 2022, an unexpectedly high detection rate of RVA was observed in February (71.0%, 22/31) and March (68.4, 13/19) (Figure 1). Age group analysis of RVA-positive cases showed that RVA can infect children of all ages. Similar RVA detection rates were seen in children aged 0-72 months (16.3%, 207/1273) and older children aged from 73 months to 16 years (18.7%, 39/209) (p =0.422). The detection rate of RVA-positive cases was highest in children aged from 25 to 36 months (18.9%, 27/143), followed by children over 73 months (18.7%, 39/209). The lowest detection rate was observed in children aged 0-12 months (14.2%, 78/551) (Figure 2). Of the 246 children infected with RVA, 64.6% (159/246) were aged 0-36 months.