Young Children Spread COVID-19 From Child Care to Their Families: Utah, 2020

By mid-2020, children aged 10 and older were known to spread the virus that causes COVID-19 efficiently, but little was known about spread from young children, especially in child care. To learn more, CDC and the Salt Lake County Health Department in Utah reviewed contact-tracing records from three child care outbreaks between April 1 and July 10, 2020. The report was posted as an MMWR Early Release on September 11, 2020.

The approach

Using Utah’s disease surveillance system, the investigators rebuilt the chains of transmission for outbreaks — two or more lab-confirmed cases within 14 days among staff or attendees at one facility. A contact was anyone within 6 feet of an infected person for at least 15 minutes, starting 2 days before symptoms began. A confirmed case had a positive RT-PCR test; a probable case had COVID-19 symptoms and an epidemiologic link, without testing. People with confirmed or probable cases isolated, and contacts quarantined for 14 days.

Salt Lake County identified 17 child care facilities — day care centers and day camps for school-age children — with at least two confirmed cases within 14 days. Three had possible spread inside the facility and complete contact data.

What they found

184 people were linked to the three facilities: 74 adults (median age 30) and 110 children (median age 7, range 0.2–16 years). Among them were 31 confirmed cases, 18 in adults and 13 in children.

Among the 101 staff and attendees, 22 were confirmed — 10 adults and 12 children. All 12 children had mild illness (9) or no symptoms (3).

Those 12 children had 83 contacts, 46 of them outside the facilities. At least 12 of those 46 caught COVID-19 — 7 confirmed and 5 probable — including six mothers and three siblings. One parent was hospitalized. Two of the three children without symptoms passed the virus on.

In two facilities, the outbreak began with a staff member who kept working while someone at home was ill with COVID-19 symptoms.

Transmission chains at the three facilities, with facility and overall attack rates. Image from CDC’s page.

The three outbreaks

• Facility A. The first case was a staff member whose household member had fallen ill 9 days earlier. A second staff member became ill 3 days later. No child was known to be infected, though none was tested.
• Facility B. A staff member tested positive before symptoms because of a sick household member; a second staff member followed, then two children — aged 8 months and 8 years — with fever, fatigue and runny noses. The two children likely infected both of one child’s parents and three other people. The 8-month-old — too young for a mask — passed the virus to both parents.
• Facility C. Two staff and two students fell ill on the same day; over the next 8 days eight more students aged 6–10, three without symptoms, and three more staff tested positive. The children likely infected seven household members, among them four mothers; one mother, presumably infected by her child who had no symptoms, was hospitalized. Fever was the most common symptom in children, then headache and sore throat. The source of this cluster was never found.

What it means

COVID-19 is milder in children than in adults, but children can still spread it — including to their families. The authors say that available testing with quick results, and testing contacts in child care regardless of symptoms, can help prevent spread and clarify children’s role in it. Staff members working while household members were ill supports CDC’s advice that staff and children quarantine and get tested when someone at home has symptoms. CDC’s guidance for child care also recommends masks, especially for staff when children are too young to wear them, with hand hygiene, frequent cleaning of high-touch surfaces, and staying home when sick.

Limitations

• Contact-tracing methods changed during the pandemic.
• At first only people with fever, cough or shortness of breath were tested, so cases and spread may be undercounted.
• Facility C’s source was unknown, so some of its cases may have come from outside.

Sources

Based on Lopez AS, Hill M, Antezano J, et al., "Transmission Dynamics of COVID-19 Outbreaks Associated with Child Care Facilities — Salt Lake City, Utah, April–July 2020," Morbidity and Mortality Weekly Report, Centers for Disease Control and Prevention; written with the Salt Lake County Health Department and the Utah Department of Health and rewritten in hubnx’s own words. The report’s discussion gives the share of outside contacts infected as 25%; its results give 12 of 46, the figure used here.