Covid Delta variant in education settings: new report

Most children diagnosed with COVID-19 during the current outbreak, including those who caught the infection in educational settings, experienced mild or no symptoms, with only 2 percent requiring hospitalisation, the latest report from the National Centre for Immunisation Research and Surveillance (NCIRS) has confirmed.

This is despite the high transmissibility of the Delta variant resulting in a five-fold increase in the spread of COVID-19 in schools, early childhood education and care (ECEC) services and households, when compared to the 2020 experience with the original strain of the COVID-19 virus.

The COVID-19 Delta variant in schools and early childhood education and care services in NSW, Australia report provides the latest data from an ongoing study by NCIRS and the University of Sydney in collaboration with NSW Health and the NSW Department of Education that has been tracking COVID-19 transmission in educational settings since March 2020.

The most recent report looks at transmission of COVID-19 in schools and households from 16 June to 31 July 2021.

"The findings of the report are consistent with recent studies overseas showing that the Delta variant is more transmissible and resulting in a greater number of COVID-19 cases among children and young people," said Professor Kristine Macartney, NCIRS Director and Professor at the University of Sydney.

"The higher transmission in schools and ECECs, and risk across the wider community, has made stay-at-home learning necessary for most children during the current epidemic period, while we work to achieve higher levels of vaccination rates among school and early childhood staff, and the adult population more generally."

This study monitored all cases where a staff or student with COVID-19 attended a school or ECEC service while infectious, tracking all secondary contacts and also calculating virus transmission rates in associated households when a case of COVID-19 developed in a school or ECEC contact.

• In 51 educational settings (19 schools and 32 ECEC services) there were 59 individuals (34 students and 25 staff members) with COVID-19 who attended the educational setting while infectious. For these 59 primary (first) cases, 2,347 close contacts from schools and ECEC services (1,830 students and 517 staff members) were identified. Testing for SARS-CoV-2 infection occurred for 96 percent of close contacts.
• Most children in this study had no or only mild symptoms from COVID-19, while 2 percent across the state required hospitalisation.
• The overall transmission rate from primary cases to close contacts was 4.7 percent (106 secondary cases, comprising 69 students and 37 staff members, in 2,253 tested close contacts). Virus transmission occurred in 19 of the 51 educational settings (38 percent; 3 primary schools and 16 ECEC services).
• The highest transmission rates occurred in ECEC services between staff members (16.9 percent) and from a staff member to children (8.1 percent). ECEC services were fully open with high attendance rates during this period and many staff were not yet age-eligible for vaccination. The majority of affected ECEC services (28/32) were in the Local Government Areas (LGAs) with the highest community incidence rates of COVID-19 in Sydney.
• Transmission was low in schools (1.2 percent; 9 secondary cases in 728 close contacts). This was likely due to the school holiday period and subsequent limited onsite attendance in Term 3, when the majority of Greater Sydney was under stay-at-home orders and students engaged in remote learning.
• Staff and children who caught COVID-19 at a school or ECEC service often passed it on to their household members. There were 181 household tertiary cases following exposure to the 106 secondary cases from the school or ECEC service. The overall transmission rate among household contacts was 70.7 percent.
• The rate of transmission of the SARS-CoV-2 Delta variant in both schools and ECEC services, as well as in households was around five times higher than seen in educational settings and households in this study in 2020 with the original strain of the COVID-19 virus.

These results should give confidence to families, schools and the community that we have robust evidence on how the Delta variant behaves in children and educational settings.

Dr Archana Koirala, a paediatric infectious disease specialist and Clinical Associate Lecturer at the University of Sydney leading the study, noted that full participation in education services is essential for children to learn and develop socially and for family and societal functioning.

"These results should give confidence to families, schools and the community that we have robust evidence on how the Delta variant behaves in children and educational settings. This evidence is being used to design strategies for returning to face-to-face learning safely as we learn to live with COVID-19," Dr Koirala said.

An additional 91 educational settings in NSW were identified between 1 August and 19 August 2021 as having a COVID-19 case(s) attend while infectious. Data on COVID-19 transmission in these settings will be included in the next report.

The study team also previously published the first comprehensive, population-based assessment of COVID-19 transmission in educational settings globally in August 2020 in The Lancet Child and Adolescent Health journal and released four school-term based reports on the study.

Disclaimer: Researchers from National Centre for Immunisation Research and Surveillance (NCIRS) and University of Sydney, with the support of the NSW Ministry of Health and NSW Department of Education, have been conducting surveillance of SARS-CoV-2 transmission in educational settings since the beginning of the 2020 school year in New South Wales, Australia. Term 1 2020 data was published in The Lancet Child & Adolescent Health. The report released today uses the same methodology but has not yet been submitted for publication or peer-review.