#15,453
Whenever a new infectious disease emerges, the learning curve on how it affects humans can be both prolonged and steep. Early assumptions are usually based on similar disease outbreaks of the past, often paired with `best case scenarios'.
Because the 2002-2003 SARS virus only appeared contagious in symptomatic cases, asymptomatic transmission of COVID-19 was deemed `unlikely' early in the COVID-19 pandemic. Even after reports of asymptomatic carriage and transmission began to emerge in Bavaria in late January, there was push-back against the idea.
We've seen similar slow realizations about the scope of SARS-CoV-2's impact on human physiology (see Nature Med. Review: Extrapulmonary manifestations of COVID-19), and persistent claims - despite ample evidence to the contrary - that children are `nearly immune' to the infection.
Questions remain, however, over the ability to detect (via overt symptoms) COVID-19 in children, the extent of carriage and shedding of the virus in children, and the role that mildly ill or asymptomatic children may play in the spread of the disease (to other children, and to other more vulnerable adults).Most recent studies suggest they are equally susceptible to infection, but with some exceptions (see MMWR: COVID-19–Associated Multisystem Inflammatory Syndrome in Children — U.S., March–July 2020), children tend to experience much milder illness.
- There is conflicting published evidence on the impact of school closure/re-opening on community transmission levels, although the evidence from contact tracing in schools, and observational data from a number of EU countries suggest that re-opening schools has not been associated with significant increases in community transmission.
- Available evidence also indicates that closures of childcare and educational institutions are unlikely to be an effective single control measure for community transmission of COVID-19 and such closures would be unlikely to provide significant additional protection of children’s health, since most develop a very mild form of COVID-19, if any.
Six weeks ago, in JAMA PEDS: Nasopharyngeal Viral RNA Higher In Young Children Than Adults, we looked at evidence that children may be highly effective vectors of SARS-COV-2.
A day later, in MMWR: SARS-CoV-2 Transmission At A Summer Day Camp - Georgia, June 2020, we looked at a study that found - even when following many (but not all) of the CDC Suggestions for Youth and Summer Camps - the pandemic virus spread efficiently among camp goers.
From the study's conclusion:
These findings demonstrate that SARS-CoV-2 spread efficiently in a youth-centric overnight setting, resulting in high attack rates among persons in all age groups, despite efforts by camp officials to implement most recommended strategies to prevent transmission.
A month ago, in J. Peds: Pediatric SARS-CoV-2: Clinical Presentation, Infectivity, and Immune Responses, we looked at a study by Researchers at Massachusetts General Hospital (MGH) and Mass General Hospital for Children (MGHfC) that measured the amount of viral RNA in the upper airway of SARS-CoV-2 positive children and found - even in asymptomatic or mildly symptomatic children - that it was significantly higher than in hospitalized adults with severe symptoms.
The authors made the case that children - even those who are asymptomatic - are likely to be efficient spreaders of the virus, and that a rushed reopening of schools - or an over reliance on temperature and/or symptom checking to screen for the disease - could help exacerbate the pandemic.
All of which brings us to a new MMWR Report, published late last week, that examines 3 COVID-19 outbreaks at child care centers in Utah, and follows up with contact tracing and testing of contacts outside of the day-care facilities.
To no great surprise, this reports finds additional evidence that both symptomatic and asymptomatically infected children can - and sometimes do - transmit the virus to others.
This report highlights the need for child care centers and their staff to adhere to CDC guidelines in order to reduce the risk of infection, and further spread of the virus. I've only included the link, summary, and excerpts from the discussion. Follow the link to read the study in its entirety.
Early Release / September 11, 2020 / 69Adriana S. Lopez, MHS1; Mary Hill, MPH2; Jessica Antezano, MPA2; Dede Vilven, MPH2; Tyler Rutner2; Linda Bogdanow2; Carlene Claflin2; Ian T. Kracalik, PhD1; Victoria L. Fields, DVM1; Angela Dunn, MD3; Jacqueline E. Tate, PhD1; Hannah L. Kirking, MD1; Tair Kiphibane2; Ilene Risk, MPA2; Cuc H. Tran, PhD1 (View author affiliations)View suggested citationSummaryWhat is already known about this topic?Children aged ≥10 years have been shown to transmit SARS-CoV-2 in school settings.What is added by this report?Twelve children acquired COVID-19 in child care facilities. Transmission was documented from these children to at least 12 (26%) of 46 nonfacility contacts (confirmed or probable cases). One parent was hospitalized. Transmission was observed from two of three children with confirmed, asymptomatic COVID-19.What are the implications for public health practice?SARS-CoV-2 Infections among young children acquired in child care settings were transmitted to their household members. Testing of contacts of laboratory-confirmed COVID-19 cases in child care settings, including children who might not have symptoms, could improve control of transmission from child care attendees to family members.
(SNIP)
DiscussionAnalysis of contact tracing data in Salt Lake County, Utah, identified outbreaks of COVID-19 in three small to large child care facilities linked to index cases in adults and associated with transmission from children to household and nonhousehold contacts. In these three outbreaks, 54% of the cases linked to the facilities occurred in children. Transmission likely occurred from children with confirmed COVID-19 in a child care facility to 25% of their nonfacility contacts.Mitigation strategies§ could have helped limit SARS-CoV-2 transmission in these facilities. To help control the spread of COVID-19, the use of masks is recommended for persons aged ≥2 years.¶ Although masks likely reduce the transmission risk (5), some children are too young to wear masks but can transmit SARS-CoV-2, as was seen in facility B when a child aged 8 months transmitted SARS-CoV-2 to both parents.The findings in the report are subject to at least three limitations. First, guidance for contact tracing methodology changed during the pandemic and could have resulted in differences in data collected over time. Second, testing criteria initially included only persons with typical COVID-19 signs and symptoms of fever, cough, and shortness of breath, which could have led to an underestimate of cases and transmission. Finally, because the source for the outbreak at facility C was unknown, it is possible that cases associated with facility C resulted from transmission outside the facility.COVID-19 is less severe in children than it is in adults (6,7), but children can still play a role in transmission (8,9). The infected children exposed at these three facilities had mild to no symptoms. Two of three asymptomatic children likely transmitted SARS-CoV-2 to their parents and possibly to their teachers.
Having SARS-CoV-2 testing available, timely results, and testing of contacts of patients in child care settings regardless of symptoms can help prevent transmission and provide a better understanding of the role played by children in transmission.
Findings that staff members worked while their household contacts were ill with COVID-19–compatible symptoms support CDC guidance for child care programs recommendations that staff members and attendees quarantine and seek testing if household members are symptomatic (4).
This guidance also recommends the use of face masks, particularly among staff members, especially when children are too young to wear masks, along with hand hygiene, frequent cleaning and disinfecting of high-touch surfaces, and staying home when ill to reduce SARS-CoV-2 transmission.
