Four genotypes of the GII.2 strains, including GII.P2-GII.2 (13 strains), GII.Pe-GII.2 (one strain), GII.P12-GII.2 (one strain), and GII.P16-GII.2 (36 strains), were determined by the Norovirus Typing Tool (Figure 1). Of them, GII.P16-GII.2 strains were the most prevalent genotype after 2009. The single GII.P12-GII.2 and GII.Pe-GII.2 strains were detected in 2004 and 2014 respectively. The GII.P2-GII.2 strains were detected throughout the investigation periods.