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The vast majority of children who become infected with Covid-19 in Australia have mild or no symptoms and caught it at home from their parents rather than at school, according to a landmark report.
New research published today by the National Centre for Immunisation Research and Surveillance has found the greatest risk of kids contracting the virus is through household spread.
Professor Kristine Macartney, a specialist at Sydney's Children's Hospital at Westmead, said today the findings should reassure parents about the safety of schools and the need for parents to get vaccinated to protect their kids.
While rising numbers of children are getting infected – according to the new data, one in three people who contracted Covid since June in Sydney were children or teenagers aged under 18 – most had few symptoms.
"The majority of children (98 per cent) had asymptomatic or mild infection," she said.
"Covid-19 is mild among children. Only around two per cent will require hospitalisation and for many of those two per cent, it's for monitoring and social care. Unfortunately, often their parents are unwell with Covid-19 and that's why they're being cared for in the hospital."
The new data is based on infections between June and August and is based on 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 spread of the virus in schools and early learning centres was also largely between adults. However, the focus of the study was transmission since June – when most schools were in lockdown and conducting online learning.
"What we saw was that the highest rate of spread was actually amongst unvaccinated adult staff and particularly unvaccinated adult staff at the time of the report in childcare centres," she said.
"The spread of virus also occurred from adults to children but the spread between children themselves was very low.
"This really affirms what we know about the Delta virus. We've seen a higher rate overall of spread from the Delta virus compared to what we saw last year but in children in particular, the majority of children who have become infected have not had symptoms or had only mild symptoms and this is certainly the case for the children infected in educational centres as well."
Going forward, McCartney said masks should be worn by teenagers attending high school and even younger children if they wished to do so.
"I know that advice is in the return-to-school plan and certainly from age 12 and above, masks are, you know, to be implemented," she said.
"That is my understanding, but also masks can be worn by younger children and I know that that may be required in the future and it's a strong option for families to consider and we're pleasingly seeing children come on board and wearing masks."
Among the total of 2,864 children infected, the largest single group were teenagers – 39 per cent of cases.
According to the new figures 810 – 28 per cent – were aged 0–5 years, 945 – 33 per cent – were aged 6–12 years and 1,109 – 39 per cent – were aged 13–18 years.
Of the children admitted to hospital, two were born in hospital and 68 were admitted from the community. 25 cases were admitted for social and vulnerable reasons, and 43 were hospitalised for medical reasons.
Of these 43, five young unvaccinated people (aged 15–18 years) required intensive care, some of whom had medical conditions other than Covid-19 that influenced their ICU admission.
Of the Covid-19 cases in children and young people, where the investigation of the source of infection has been completed, 1,680 (88 per cent) had acquired infection from household contacts.
But the report also warns the Delta strain is "five times" more transmissible than the original virus.
"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," Macartney said.
Key findings from the research include:
• 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 per cent of close contacts.
• Most children in this study had no or only mild symptoms from Covid-19, while two per cent across the state required hospitalisation.
• The overall transmission rate from primary cases to close contacts was 4.7 per cent (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 per cent; three primary schools and 16 ECEC services).
• The highest transmission rates occurred in ECEC services between staff members (16.9 per cent) and from a staff member to children (8.1 per cent). 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 per cent; nine 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 per cent.
• The rate of transmission of the SARS-CoV-2 Delta variant in both schools and the 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.
Dr Archana Koirala, a paediatric infectious disease specialist and Clinical Associate Lecturer said parents should be reassured by the findings.
"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," Koirala said.
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