COVID-19 Delta & Omicron variant in education settings: new report

21 February 2022

How COVID variants behave in educational settings

The latest report on COVID-19 transmission in NSW schools in Term 4 shows secondary cases did not dramatically increase, despite the appearance of Omicron occurring in the latter part of 2021.

Spread of COVID-19 in NSW schools, early childhood education and care services during 18 October 2021 to 17 December 2021 did not dramatically increase, despite the emergence of the Omicron variant and a sharp rise in case notifications and school exposure events in late 2021. 

The COVID-19 in schools and early childhood education and care services in NSW, Australia term 3 and term 4 2021 report provides the latest data from an ongoing study by the National Centre for Immunisation Research and Surveillance (NCIRS) and the University of Sydney, in collaboration with NSW Health and NSW Department of Education, which has tracked transmission of COVID-19 in educational settings since March 2020. 

In Term 4 2021, the majority of students returned to the classroom. There were 985 exposure events involving 1,206 individual ‘index’ (first) cases across the 3,107 NSW schools. More than four in five of the index cases were students and the remainder were staff. 

The overwhelming majority of these index cases were unvaccinated, according to this latest report.

“61 percent of school exposure events in Term 4 were in primary schools – consistent with the very low numbers of 5 -to-11 year olds vaccinated prior to the January 2022 rollout of the vaccination program for this age group,” says NCIRS Director and University of Sydney Professor of Paediatrics and Child Health Kristine Macartney

“School staff also represented a greater proportion of cases following the introduction of Omicron from late November, emphasising the need for booster vaccination in this group,” Professor Mcartney said.

From 18 October to 17 December 2021, there were 23,899 locally acquired COVID-19 cases in NSW, of which 33 percent were in people aged up to and including 19 years old.

Dr Archana Koirala, Clinical Associate Lecturer at the University of Sydney who is leading the study, said: “Even with the high numbers of exposure events in Term 4, we did not see a dramatic increase in onward transmission in schools. 

“In high schools, onward transmission was lower, likely a result of strong COVID-19 vaccine uptake by staff and children aged 12 years and over, as well as other prevention strategies,” Dr Koirala said..

“Our findings confirm that vaccination of students and teachers, as well as other mitigation measures in schools and the wider community, can keep transmission low in educational settings, enabling schools to deliver the face-to-face learning that children need.” 

Resumption of full face-to-face learning in Term 4 increased the number of exposure events, from a median of 22 schools per week in Term 3 with a median 10 per cent attendance to 87 schools per week with a median 89 per cent attendance. About half of all Term 4 school COVID-19 exposures occurred in the fortnight of 4–17 December 2021. 

However, the ‘secondary’ attack rate – the proportion of close contacts in educational settings infected after being exposed – remained low in Term 4 at 2.9 percent overall, and lowest in high schools at 1.0 percent. There was a modest increase in transmission in the last part of Term 4 in schools where the Omicron variant was introduced (3.7 percent), compared with schools with the Delta variant (secondary attack rate 2.4 percent).

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. They have also released additional school-term based reports on the study.

For the full reports, visit


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.

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Ivy Shih

Media and Public Relations Adviser (Medicine and Health)

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