Delta’s impact on Australian children becomes clearer

Transmission at schools and early childhood education and care (ECEC) services is occurring at a rate five times higher than 2020, new research from the National Centre for Immunisation Research and Surveillance (NCIRS) suggests.
 
The study, which analysed the spread and severity of COVID-19 cases among children from the start of the recent large-scale outbreak in Sydney, revealed there had been a secondary attack rate of 4.7% at school and childcare sites between 16 June and 31 July, compared to 0.9% last year.
 
However, it also showed that the vast majority of children (98%) had asymptomatic or mild cases of COVID-19 and reaffirmed that they are significantly less likely to pass on the SARS-CoV-2 virus than adults.
 
Transmission was also far higher in ECEC services, which remained open for the duration of the study, compared to primary and secondary schools where many students moved to remote learning on 25 June.
 
For Dr James Best, Chair of RACGP Specific Interests Child and Young People’s Health, the biggest concern highlighted by the survey is the rate of transmission in household settings, rather than the impact of the illness on children.
 
‘It’s really good that we have this data,’ he told newsGP. ‘It really helps us inform our decisions.
 
‘The anxiety that parents have about children is a big issue. As GPs, we have to deal with that, so I think it’s really good to have this data to show that even though children can spread it, especially with the Delta variant, the health consequences to them are very mild.’

The flow-on effect
With so few children experiencing anything other than mild or no symptoms, Dr Best believes the ‘flow-on’ effect in households is the main source of concern.
 
‘It’s extraordinary that 70% of household contacts of a primary case would get the disease, and in over half of households the entire household got it,’ he said.
 
‘If a school-age child gives it to an elderly relative that’s who ends up in ICU. That’s the pathway that we worry about.’
 
In the study, 59 confirmed primary COVID-19 cases were identified as having the potential to spread the virus in 51 schools or childcare sites, including 34 students and 25 members of staff.
 
For those cases there were 1830 students and 517 staff members recorded as close contacts, leading to 106 secondary cases being identified in 19 of the 51 educational settings (37%). The highest transmission rate was recorded between staff members in ECEC services (16.9%).
 
However, the spread recorded among the contacts of those secondary cases was greater still. The report cited a tertiary attack rate of 70.7%, resulting in 181 further cases and transmission in 76 of 96 households. In 55 instances (57% of the total) all household members contracted COVID-19.
 
Of all the children infected across Sydney where the source of infection was identified, 88% were acquired from household contacts.
 
Low hospitalisation
The report also includes overall details of COVID-19 in children and young people from 16 June–19 August, who accounted for 2864 of positive cases (27% of the total) in that time.
 
There were 810 cases (28%) among those aged 0–5 years, 945 (33%) aged 6–12, and 1109 (39%) were aged 13–18.
 
The majority (98%) had asymptomatic or mild infection, while 70 were hospitalised, including two who were born in hospital and 68 admitted from the community. Of those, 25 cases were admitted for social rather than medical reasons.  
 
Of the remaining 43, five unvaccinated young people aged 15–18 needed intensive care. The NCIRS study said some of those five had medical conditions other than COVID-19, which influenced the decision to admit them to ICU.
 
‘Severe COVID-19 in childhood remains very low,’ Dr Best said. ‘That’s a message that really needs to get through to the public. It is very rare for children to get serious disease.’
 
Vaccination
Despite the low chance of serious disease, new analysis from the ANU Centre for Social Research and Methods suggests most parents remain willing to have their children vaccinated when possible.
 
The survey data, taken from responses regarding 1368 children in 763 homes, recorded 42.5% of parents and carers saying they would definitely vaccinate young people in their household, while 36.3% would probably get their child vaccinated. Of the rest, 11.4% said they would probably not get their child vaccinated while 9.8% said they would definitely not.
 
But for Dr Best, the NCIRS work reinforced most strongly the need for widespread vaccination among adults, including staff members at schools and childcare centres, as well as parents and carers.
 
‘If your child might be bringing it home from school, you’re the one that may cop it,’ he said. ‘This is more reason for adults to be vaccinated.’
 
Difficult decisions
The NCIRS survey also cites previous research on the impact of limiting access to education, including an OECD study that suggested losing a third of the school year reduced future earned income of affected students by an estimated 3%. 
 
The study, published last September, found the impact of lockdown would not be evenly spread across the population and that disadvantaged students ‘will almost certainly see larger impacts’.
 
Dr Best agrees that the decision-making process for lockdowns is highly fraught.
 
‘It’s a complicated issue because there are obviously very significant downsides to having children away from school – the effect on families, including the effect on their education trajectory,’ he said.  
 
‘This is what the regulatory authorities are trying to balance up. Anybody who thinks this is a simple issue is kidding themselves.’
 
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