Table 2. CICT Performance and Estimated Outcomes, by US Census Region, November 25, 2020, to January 23, 2021^a.

US Census regions	No. of statesc	Total population	Daily COVID-19 incidence per 100 000, mean (range)	Median (range)
				CICT performance measureb			Estimated cases averted		Estimated cases averted per 100 000 population
				Time from infection to isolation, d	Cases isolated, low, %	Cases isolated, high, %	Low	High	Low	High
Midwest	5	30 947 757	58 (42-75)	7 (6-7)	17 (15-25)	19 (18-28)	73 780 (19 577-121 865)	84 523 (23 221-158 766)	1444 (639-2213)	1600 (838-2727)
Northeast	5	25 348 752	59 (19-92)	7 (6-10)	16 (4-35)	19 (5-34)	32 084 (5921-66 362)	41 194 (7005-86 692)	900 (53-6139)	1155 (62-8183)
South	7	33 384 859	55 (22-88)	8 (7-12)	19 (14-41)	24 (16-49)	21 170 (5466-120 157)	27 473 (6452-156 557)	670 (80-1987)	895 (94-2590)
West	6	49 893 913	61 (28-94)	8 (7-9)	14 (4-23)	17 (5-24)	19 484 (4858-207 417)	24 326 (5721-252 325)	488 (271-704)	568 (336-856)
Total	23	139 575 281	58 (19-94)	7 (6-12)	17 (4-41)	19 (5-49)	22 014 (4858-207 417)	27 473 (5721-252 325)	704 (53-6139)	895 (62-8183)

Abbreviation: CICT, Case Investigation and Contact Tracing.

^a US Census regions are defined by the US Census Bureau.¹¹

^b Days from infection to isolation were calculated using jurisdictions’ reported days from testing to case and contact notification, the COVID-19 incubation period, and assumptions regarding the timing of entry into isolation or quarantine after notification. Percentage of cases isolated was calculated from jurisdictions’ reported metrics on CICT program performance, such as the proportions of cases interviewed and contacts notified or monitored. The lower estimates assume a fraction of interviewed cases and contacts complied with isolation and quarantine guidelines, whereas the high estimates assume all interviewed cases and monitored contacts did so (Table 1 and eAppendix 1 in Supplement 1).

^c Includes 22 states (3 with a major city excluded) and 1 territory.