Despite Delta being more transmissible than earlier Covid-19 variants, in Australia few children and adolescents who get the virus have severe symptoms, and schools should only be closed under exceptional circumstances, a research analysis from the Murdoch Children’s Research Institute has found.
However, the analysis reveals children and adolescents living with some pre-existing health conditions, including obesity, and those living in disadvantage, low socioeconomic communities or those with minority ethnic status have an increased risk of severe disease.
The analysis also said ventilation is important and mental health surveillance is needed across both primary and secondary schools.
“In Early Childhood Education Centres [ECEC] and school settings, transmission is largely seen between adults and from adults to children,” the report said. “Although child-child transmission also occurs, the highest risk of transmission remains within households.
“The best way to protect children from Covid-19 is for all their eligible household contacts to be vaccinated, together with ECEC and school staff.”
Since the emergence of Delta, the rate of infection in children and adolescents in Victoria has increased, with those under 18 comprising 30% of all Covid-19 cases in the state which occurred between 1 May and 5 September, the analysis found. In NSW, those under 18 years of age made up 27% of all cases that occurred between 16 June and 19 August.
This is approximately double the proportion seen in 2020, or in the first half of 2021.
“These differences can be explained by the increased transmission of Delta in a largely non-immune population, and a relative shift of infections to the younger age groups because a large proportion of adults are now protected by vaccination,” the report said.
Researchers also examined international data from England, Scotland, Canada, the US and Singapore to make the recommendations in their report, which has been used as a basis for schools reopening in Victoria.
Senior principal research fellow with the Murdoch Children’s Research Institute, Prof Fiona Russell, said many schools in the northern hemisphere re-opened despite significant levels of Covid-19 transmission within the community, due to the negative physical, mental and educational impact closures had on children.
“To balance the higher transmissibility of Delta with the importance of face-to-face learning, many countries have implemented a series of mitigation strategies, including vaccination of staff and children over 12 years of age, rapid testing and mask-wearing,” she said.
“It’s important that these strategies are age-appropriate and strike a balance between infection control and enabling learning and social interactions.”
In the UK, a survey conducted from November 2020 to July 2021 found schools were not the main source of infection, consistent with reports from Finland. In both countries, transmission in schools occurred largely between staff.
When children returned to school in England in September, this was followed by an increase in infections in children and adolescents, which has started to decline again in the past week. However, vaccination of 12 to 15-year-olds has only just begun and face masks are not worn or recommended for students or teachers, the report said.
The Victorian government recommends mask-wearing for all students, with a mandate for those in grade three and up. In NSW, masks are required indoors for all staff and students in year 7 and above, and are strongly recommended but not mandated indoors for primary students.
As well as masks for those age five and above, the report recommends rapid testing, as it can limit school outbreaks by reducing the number of new infections, especially from asymptomatic cases.
“Victoria and NSW aim to incorporate rapid testing models into schools this year,” the report said.
Ventilation is also important, the analysis said. Research at the Royal Melbourne Hospital found 99% of aerosols can be cleared from patient rooms using purification devices.
“Other measures to improve air flow include opening windows, doors and teaching outdoors, where possible, may assist with increasing air exchanges,” the report recommends, though it acknowledged these measures were likely to be highly variable between early childhood education centres and schools.
Ongoing Covid-19 monitoring in education is still needed to monitor the success of mitigation measures in place, the report said, adding that mental health surveillance is needed across both primary and secondary schools.
“These data will also inform management of other respiratory viruses and future pandemics,” the report concluded. “Outbreak management in ECEC and schools should consider the strategies that minimise disruption to face-to-face learning and keep children at school where possible.”
