Table 1. Characteristics of study population and number of samples submitted per country and time period.

Continent	Country	Country totals	Row totals	Pandemic onset1,2	Sampling period (year/week)	Diversity index categories
						1	2	3	4
						0–1.5	1.5–2.5	2.5–3.5	3.5–4
North America	Canada	913	444	Pre	08/40–09/32	6.8	34.7	45	13.5
			469	Post	09/33–10/26	1.1	17.1	48	33.9
	Mexico (central)	579	272	Pre	09/26–09/45	21	40.4	32.7	6.2
			307	Post	09/46–10/24	8.1	41.7	36.2	14
	Mexico (northern)	432	432	Pre	09/01–09/044	18.8	50.9	26.6	3.7
			0	Post	NA
	USA	520	130	Pre	09/28–09/40	0.8	24.6	47.7	26.9
			390	Post	09/41–10/26	0.3	8.7	38.7	52.3
Europe	The Netherlands	559	188	Pre	09/27–09/45	1.6	46.8	40.4	11.2
			371	Post	09/46–10/30	0.5	32.1	50.1	17.3
	Portugal	479	130	Pre	09/28–09/40	13.8	54.6	28.5	3.1
			349	Post	09/41–10/23	5.2	33.8	44.4	16.6
	Sweden	868	526	Pre	08/40–09/40	2.5	46.4	44.3	6.8
			342	Post	09/41–10/22	0.3	20.2	49.1	30.4
	Switzerland	637	180	Pre	09/23–09/40	3.3	31.1	52.2	13.3
			457	Post	09/41–10/34	3.5	33.5	50.3	12.7
	UK	568	190	Pre	09/27–09/45	7.9	39.5	40	12.6
			378	Post	09/46–10/30	2.6	27.5	47.4	22.5
Asia	India	474	120	Pre	09/28–09/40	4.2	31.7	51.7	12.5
			354	Post	09/41–10/25	3.4	34.5	48.3	13.8
	Japan	530	140	Pre	09/27–09/40	1.4	21.4	51.4	25.7
			390	Post	09/41–10/26	0.3	13.6	47.7	38.5
	Lebanon	337	337	Pre	09/02–09/44	11.3	49.3	34.4	5
				Post	NA
Africa	South Africa	276	248	Pre	09/29–10/15	12.1	48	35.1	4.8
			28	Post	10/16–10/21		42.9	42.9	14.3
South America	Argentina	412		Pre	NA
			412	Post	09/27–10/16	6.6	37.1	43.4	12.9
Total range of study weeks:					08/40–10/34
Totals per pandemic period	pre: 3337	post: 4247
Totals per diversity category						416	2548	3272	1384
Total									7584

¹Pandemic onset of A(H1N1)pdm09; ²pre- and post pandemic onset of circulation of A(H1N1)pdm09 per respective country, percentages are represented within pandemic period; NA: not available.

Diversity index categories reflect percentage of individuals within the respective category.