Table 3. The median transmission duration, cluster size and growth rate of clusters with different number of serotypes present in Singapore (2014–2016), and separated by low^a and high^b risk areas.

No. of serotypes in cluster	Median transmission duration (days)			Median cluster size (no. of cases)			Median growth rate (no. of new cases per day)			No. of clusters
	Combined*	Low risk areas	High risk areas	Combined*	Low risk areas	High risk areas	Combined*	Low risk areas	High risk areas	Combined	Low risk areas	High risk areas
1	13	13	13	4	4	4	0.28	0.28	0.28	1319	168	1129
2	21	18	21	7	7	7	0.35	0.34	0.35	328	32	291
3	53	n/a	93	25	n/a	70	0.52	n/a	0.68	31	0	30
4	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	n/a	0	0	0

^a Low risk areas are RG 1 and RG 2 grids.

^b High risk areas are RG 3 and RG 4 grids.

n/a, data not available

Kruskal-Wallis test (P <0.01 are highlighted by *)