There was a total of 8309 and 3928

There was a total of 8309 and 3928 cases of rotavirus and norovirushospitalizations among children under 5 years old from 2002 through2011 in Hong Kong, respectively. Of all these cases, 7263 (87.4%) and2233 (56.8%) hospitalizations due to rotavirus and norovirus infectionwere recorded in winter, respectively. Table 1 summarizes the descriptive statistics for daily counts of rotavirus and norovirus admissions anddaily total rainfall, mean temperature and RH during the entire studyperiod. Time-series of hospitalizations due to these two types of infections as well as meteorological variations are shown in Fig. 1. Rotaviruswas consistently commonly circulated in winter when the least rainfallwas recorded throughout the year whereas norovirus hospitalizationshowed a bi-annual pattern, including a major peak in winter and aminor peak in summer, with one exception in the summer of 2006when an unusually large epidemic was reported. While hospitalizationsfor both diseases were more common in the winter, the winter predominance of rotavirus hospitalizations was much stronger than that fornorovirus.