1. Note: *untypeable Supplement 1. A quarterly distribution of G and P type combinations detected in Vietnam, 2012-2015 Year 2012201320142015 Grand Total Genotype Jan- Mar Apr-JunJul-SepOct-Dec Yearly Total Jan-MarApr-JunJul-SepOct-Dec Yearly Total Jan-MarApr-JunJul-SepOct-Dec Yearly Total Jan-MarApr-Jun Half- yearly Total G1P[8] 9810336542917679488829151356791627613757 G2P[4] 1420 30153101945324586322052187 G8P[8] 00000000000003310263639 G3P[8] 33006010233010410114 Others 12036101021011302213 G1+G8P[8]0000000000000003033 G2+G8P[8]0000000000000221013 G2+G8P[4]+P[8]0000000000000003033 G1+G2+G8P[4]+P[8]0000000000000000 111 Other Mixed 01067151073121622471147 UT* 1032654021100279761339

2. Wa RVN14.1149 RVN15.0138 RVN15.0162 RVN15.0357 KUN Wa KUN RVN15.0138 RVN15.0149 RVN15.0162 RVN15.0281 RVN15.0310 RVN15.0357 RVN15.0376 RVN15.0475 RVN15.0377 RVN15.0383RVN15.0427 RVN15.0630 RVN15.0600RVN15.0632 RVN15.0634 RVN15.0511 RVN15.0648 2 4 5 6 7 8 9 10 11 1 3 Supplement 2

3. Supplement 2. Electrophoretic migration pattern of genomic double-stranded RNA of Vietnamese G8P[8] RVA strains detected between October 2014 and May 2015 alongside Wa (long RNA pattern) and KUN (short RNA pattern) as positive controls on 10% polyacrylamide gel stained with silver nitrate. Strain names are indicated at the top of each lane on the gel while numbers on the left side represent the genome segment number. All specimens possessed short RNA patterns almost indistinguishable from each other. Strain RVN14.1149 was detected the earliest and possessed the predominant electropherotype.

4. Supplement 3

5. Supplement 3. A maximum clade credibility tree of VP7 nucleotide sequences of eight Vietnamese G8P[8] strains and the other closely related G8 strains within lineage IV (Fig. 1). The analysis was conducted using the Bayesian Markov chain Monte Carlo framework implemented in BEAST software package v.1.8.1; the TN93 + G substitution model, a coalescent constant size tree prior and a lognormal relaxed clock model were assumed for the analysis. Two independent runs were carried out for twenty million generations and assessed with the Tracer software v.1.6 (http://tree.bio.ed.ac.uk/software/tracer/). The tree was annotated with a TreeAnnotator and viewed in FigTree software v.1.4.2 (http://tree.bio.ed.ac.uk/software/figtree/).http://tree.bio.ed.ac.uk/software/tracer/http://tree.bio.ed.ac.uk/software/figtree/