In late September 2020, the incidence of confirmed COVID-19* in North Dakota began
increasing rapidly, from approximately 300 new cases per day to approximately 2,260
cases on November 13, 2020 (
1
). On October 20, the North Dakota Department of Health reported that contact tracing
notification efforts were delayed. Because of the delay, COVID-19 patients were asked
to notify their own contacts about potential exposure and encourage them to seek testing
for SARS-CoV-2, the virus that causes COVID-19 (
2
). The Spirit Lake sovereign nation in east central North Dakota is home to approximately
7,500 members of the Spirit Lake Tribe. In response to increasing incidence of COVID-19
on the Spirit Lake Reservation, CDC assisted the Spirit Lake Tribe in building a tribally
managed program for comprehensive COVID-19 case investigations, case notification,
contact tracing, contact testing, and contact management to ensure timely implementation
of these critical epidemic control measures.
Through the Spirit Lake Tribe case investigation and contact tracing program, the
tribe’s COVID-19 Incident Command System staff members conducted case investigations
and contact tracing, provided COVID-19 education, followed up with patients regularly
by telephone, and monitored daily symptoms of close contacts. Members of the Spirit
Lake community served as contact tracers. Symptom monitoring was facilitated through
CDC’s Text Illness Monitoring system (version TIM2), using a free, two-way text-messaging
platform to query enrolled contacts about daily COVID-19 symptoms. The system also
alerted Spirit Lake Tribal Health authorities when participants reported symptoms
or did not to respond (
3
). This report describes case investigation and contact tracing for the Spirit Lake
Tribe during September 29, 2020 (when the case and contact tracing launched) through
November 20, 2020 (when the CDC field response ended) and lessons learned from program
implementation. This activity was reviewed by CDC and was conducted consistent with
applicable federal law and CDC policy.
†
During September 29–November 20, data were retrieved by COVID-19 response team members
from Spirit Lake Tribal Health’s COVID-19 case and contact database, including patient
demographics; links between COVID-19 patients and close contacts; test results; and
symptom onset, isolation, and quarantine dates. Symptom data from Spirit Lake’s TIM2
monitoring system were analyzed to assess COVID-19 symptoms reported by close contacts
of COVID-19 patients during October 22, (when TIM2 use began for contact management)
through November 30 (when the last close contact unit
§
enrolled by November 20 completed quarantine).
During September 29–November 20, a total of 317 persons with confirmed COVID-19 and
667 close contacts among the Spirit Lake Tribe were reported; 129 (19.3%) of these
close contacts received a subsequent COVID-19 diagnosis (Table). The average interval
between specimen collection to receipt of a positive SARS-CoV-2 test result was 2.25
days (median = 3 days, range = 0–9 days). Overall, 254 (80.1%) of 317 patients with
confirmed COVID-19 and 420 (78.1%) of 538 close contacts who did not receive a COVID-19
diagnosis were contacted by program staff members and instructed to isolate or quarantine
within 24 hours of receipt of test results or identification of cases.
¶
The proportion of confirmed new COVID-19 cases arising from known contacts was 41%
(weekly range = 24%–59%).
TABLE
Number of patients with confirmed COVID-19 and close contacts who did or did not receive
a COVID-19 diagnosis ― Spirit Lake Tribe, North Dakota, September 29–November 20,
2020*
Dates†
No. of patients with confirmed COVID-19 (% of cases from close contacts)§
Close contacts
No. who received a COVID-19 diagnosis (%)§
No. who did not receive a COVID-19 diagnosis¶
Total no.
September 29–October 2**
35 (20)
7 (10)
61
68
October 3–9
39 (59)
23 (23)
75
98
October 10–16
39 (41)
16 (18)
74
90
October 17–23
††
40 (50)
20 (25)
60
80
October 24–30
40 (38)
15 (15)
88
103
October 31–November 6
42 (36)
15 (26)
43
58
November 7–13
37 (24)
9 (9)
88
97
November 14–20
45 (53)
24 (33)
49
73
Total
317 (41)
129 (19)
538
667
* These numbers might not include all patients or close contacts associated with the
Spirit Lake Tribe because of limited sharing of health information among overlapping
state, local, and tribal jurisdictions.
†
The date used for confirmed COVID-19 patients was the date of receipt of a positive
SARS-CoV-2 test result; for close contacts the date used was the date of identification
as a close contact by a confirmed COVID-19 patient.
§ Close contacts who received a COVID-19 diagnosis were included in the total number
of patients with confirmed COVID-19 on the date that they received their positive
test result. The percentage of cases among close contacts was calculated as the number
of close contacts who received a COVID-19 diagnosis divided by the number of confirmed
COVID-19 cases.
¶ Included close contacts who received a negative SARS-CoV-2 test result, those who
did not receive testing after exposure, and SARS-CoV-2 infections not reported to
Spirit Lake Tribal Health and Spirit Lake Health Center.
** This week only contains 4 days to align with the assessed period (September 29–November).
††
During this and all subsequent weeks, close contacts of confirmed COVID-19 patients
were given the option to enroll in CDC’s Text Illness Monitoring system (version TIM2)
for daily symptom monitoring.
During October 22–November 30, a total of 44 close contact units were enrolled in
TIM2, which logged 366 responses during 524 quarantine days (70% daily response rate).
Among these 44 enrolled close contact units, 17 (39%) reported one or more persons
with symptoms, 16 (94%) of whom were contacted within 24 hours and instructed to quarantine
to prevent further transmission. A total of 20 persons from eight close contact units
received a COVID-19 diagnosis. During the assessment period, the incidence of COVID-19
in the Spirit Lake Tribe plateaued at approximately 520–600 cases per 100,000 persons
per week; during the same period, a 1.5-fold increase in incidence occurred in North
Dakota, from 455 to 1,137 cases per 100,000 per week (
1
,
4
).
Implementation of a COVID-19 case investigation and contact tracing program for the
Spirit Lake Tribe highlighted several important lessons. First, the program required
daily, continuous staffing to effect timely COVID-19 mitigation. Second, obtaining
information from and maintaining contact with COVID-19 patients and their close contacts
was challenging. Using Spirit Lake community members as investigators and contact
tracers aided in outreach because of their knowledge of alternate methods to reach
patients or contacts (in-home or family contacts) when locating information was incomplete.
These community members also helped to improve response rates about COVID-19 exposures
because they were trusted by the community and were able to provide culturally appropriate
advice about the need to isolate or quarantine. Third, shared rooms and living spaces
among multigenerational families or within whole households with cases or exposures
in this community often hindered within-home quarantine and isolation and adherence
to these measures. To address this challenge, program staff members distributed critical
supplies (e.g., groceries, over-the-counter medications, thermometers, personal protective
equipment, and cleaning supplies) and health literacy information (about daily temperature
logs, isolation and quarantine procedures, and mask use) to each household. Finally,
approximately 100 (10%) persons identified through the case investigation and contact
tracing program experienced homelessness or unstable housing during this period, necessitating
the provision of temporary shelter and meals at a motel for these persons during isolation
and quarantine.
Despite these challenges, this tribally managed COVID-19 case investigation and contact
tracing program effectively reached Spirit Lake tribal members to provide isolation,
quarantine, symptom monitoring, and support services and contributed to timely case
and contact management. This program might help guide similar programs in other tribes
and the public health community.