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Summary
- Known before: large gatherings pose a risk of spreading SARS-CoV-2.
- New here: among 60 immediate and extended family and community members of the Hopi Tribe, 29 (48%) had laboratory-confirmed COVID-19; 14% were presymptomatic and 24% had no symptoms, most of them children and young adults.
- What it means: frequent, recurring contact among extended family allowed repeated exposure to infectious people. In communities with similar family ties, promoting safe ways to stay in touch, along with masks, hand washing and physical distancing, may help limit spread.
Background
The Hopi are a Native American tribe and sovereign nation living mainly on the 1.5-million-acre Hopi Reservation in northeastern Arizona. Tribal leaders declared a COVID-19 state of emergency on March 17, 2020, followed by a stay-at-home order on March 23. The Hopi Health Care Center (HHCC), an Indian Health Service facility, reported its first case on April 13, and cases stayed low through May — until, in the two weeks before early June, new cases jumped from 1–2 to 10–15 a day.
Two sisters and a trip to town
- On May 23, a 73-year-old woman (patient A) and her 67-year-old sister (patient B) spent a few hours in a large home improvement store in Flagstaff, wearing masks, and wore masks only intermittently on the 2-hour drive home.
- Patient A fell ill on May 27 with a headache; by June 1–2 she had a worse headache, fever and shortness of breath, and tested positive on June 3. Patient B developed a runny nose and sore throat on May 28 and tested positive on June 5.
- With similar exposures, onset dates and contacts, both were treated as co-index patients. HHCC began contact tracing on June 4.
How it spread
| Setting | What happened |
|---|---|
| Office, May 27 | Patient A worked about 6 hours beside a colleague, both masking only intermittently. The colleague fell ill on June 2; of her 8 household members, 7 tested positive, and none of her four co-workers. |
| Planting dinner, May 27 | The sisters worked outdoors with 13 extended family members, then shared an indoor potluck, unmasked. |
| Graduation dinner, May 30 | The sisters dined with 23 others; three had also been at the planting dinner. In all, 11 people from the two dinners were later infected. Both dinners took place during the stay-at-home order. |
| Family visit, June 1 | Patient A's daughter, son-in-law and four grandchildren visited for hours. One granddaughter played with two friends that day and fell ill on June 2; one friend, and several of her own household, tested positive. |
| Patient B's household | Patient B had close contact with 10 family members — four at home, six next door — and five of them were infected. |
Cases by date of symptom onset, or test date for people without symptoms, May–June 2020. Chart: CDC.
The likely chains of transmission from patients A and B. Diagram: CDC.
The cases
- 58 contacts were identified; 27 (47%) tested positive — 29 confirmed cases in all, counting the sisters.
- 22 (76%) had symptoms and 7 never did. Four (14%) were presymptomatic, all under 20; of the seven without symptoms, six were under 30.
- The median age was 21 (range 1–79). 13 (45%) had at least one underlying condition, including obesity (7), diabetes (3) and cardiovascular disease (3).
- Among the infected contacts, seven had visited patient A, four were in patient B's household, one was a workplace contact, and one was a child whose six close contacts later tested positive — five in her household, where the timing suggests she brought the virus home.
- Two patients went to an emergency department, one needed critical care, and no one died.
- Interviews showed limited understanding of how and when to wear masks, keep 6 feet apart and wash hands.
Response
HHCC led the response with the Hopi Tribe. The Hopi Emergency Response Team and HHCC public health nurses arranged housing, food and other support for people in isolation and quarantine, and a communication team promoted masks, hand hygiene and distancing. Afterward, HHCC and the tribe stepped up messaging in English and Hopi, on the radio and through community health representatives.
What it means
Two extended-family gatherings and a workplace exposure carried the virus beyond households into the community. Frequent contact among extended family meant repeated exposure to the two sisters, who both had symptoms for a week or more before testing and kept socializing. Many infected children and young adults had mild or no symptoms and would have been missed without testing every contact. Everyone at home, including the sick person, should wear masks in shared spaces, and people should isolate as soon as symptoms start.
Limitations: some later contacts may have been missed; overlapping family contacts made exposure dates and contact order hard to pin down; and detailed information on masking and distancing was not always available.
Close collaboration between HHCC and the Hopi Tribe was crucial in containing the outbreak, and its lessons may help other communities with multigenerational households and close extended families.
Sources
Based on Hirschman J, Kaur H, Honanie K, et al., "A SARS-CoV-2 Outbreak Illustrating the Challenges in Limiting the Spread of the Virus — Hopi Tribe, May–June 2020," MMWR Morbidity and Mortality Weekly Report, volume 69, Centers for Disease Control and Prevention; a work of the United States government in the public domain. The report gives some shares of the infected contacts over 27 and others over 29; this page gives the counts.
Licens: CC0 1.0 (offentligt eje) · Bearbejdet efter www.cdc.gov
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