By Dr. Zoe Hyde ￼- Epidemiologist – University of Western Australia
It is widely thought that children are much less susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection than adults and do not play a substantial role in transmission. However, emerging research suggests this perception is unfounded. Seroprevalence and contact tracing studies show children are similarly vulnerable and transmit the virus to a meaningful degree. Research suggesting otherwise is hampered by substantial bias. Additionally, large clusters in school settings have been reported, with implications for the control of community transmission. Risk-reduction strategies must be implemented in schools as a matter of urgency.
Perth – An early cause for hope in the coronavirus disease 2019 (COVID-19) pandemic was the observation that children are much less likely to experience severe illness than adults.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children is generally characterised by mild illness.
More recent data paint a different picture. In a seroprevalence study of over 61,000 people from Spain, 3.4% of children and teenagers had antibodies against SARS-CoV-2 as measured by a point-of-care test, compared with 4.4% to 6.0% of adults. In a subset of almost 52,000 people who underwent immunoassay testing, the gap narrowed to 3.8% vs. 4.5% to 5.0%.
The role that children play in transmission is less certain, but there is no reason to think that children are less likely to transmit the virus than adults. In a study of symptomatic people with mild to moderate COVID-19, the amount of viral RNA detected in the nasopharyngeal swabs of children aged 5-17 years was similar to that of adults. However, young children (<5 years) had levels 10 to 100 times higher.
In a contact tracing study comprising 5,706 index cases and 59,073 contacts in South Korea, non-household contacts of child index cases were as likely to be infected as contacts of adult cases. Within the household, contacts of young paediatric index cases (<10 years) were less likely to become infected than those of adults, but the attack rate (AR) for the contacts of older children and teenagers was higher than any other group.
The government of Israel mandated complete closure of the country’s schools in mid-March. A cautious reopening was attempted less than two months later, and all schools reopened for face-to-face teaching on 17 May. Ten days later, the first major outbreak occurred in a high school.
A similarly rapid spread occurred in a private school catering for students from pre-primary to high school age in Chile.
The US closed schools in all 50 states in March. A study found this was temporally associated with a marked decrease in COVID-19 incidence and mortality, and the effect was greatest in states which acted earlier when cases were low.
A recent study of COVID-19 in educational settings in New South Wales appears to suggest a small role for schools at first glance, with limited transmission reported between January to April, although a large outbreak occurred in a childcare centre.
These limitations are unfortunately common to many studies of COVID-19 and children. Most have been conducted during lockdown periods – which are not normal conditions – or at a time of low community transmission. Adult travellers seeded epidemics and the virus initially circulated among their contacts, delaying children’s exposure. In some countries, cases were rapidly isolated and quarantined away from home, further limiting spread to children. Testing was initially limited, excluding those not fitting clinical criteria. This is of particular relevance given the high prevalence of asymptomatic infection among children, and also increases the likelihood that index cases in children will be missed. Paediatric cases may only be detected after transmission from the child to a second person (often an adult) has occurred. The child may then be tested as a contact, and either mistakenly thought to be a secondary case, or missed entirely if the child’s viral load has declined by this point. Finally, limited transmission by children in some studies
This complacency cannot continue. The situation in Victoria provides stark warning to the rest of Australia. As community transmission has grown, clusters have arisen in educational settings catering for children of all ages.
Schools are clearly neither inherently safe nor unsafe. The risk associated with these settings depends on the level of community transmission, and it must be continuously evaluated. Schools must not remain open for face-to-face teaching in the setting of ongoing community transmission. In regions where community transmission is minimal, risk-reduction strategies must be implemented in schools as a matter of urgency. Comprehensive guidelines have been developed (summarised in Box 1),
The evidence clearly shows that children and schools are at risk, with wider implications for the community. Additionally, serious outcomes in children will become increasingly common – at least in absolute terms – if the virus is allowed to spread. We can no longer afford to overlook the role children play in transmission if we hope to contain the virus. — Medical Journal of Australia, Dr. Zoe Hyde
Students and staff should wear face masks
Wash hands frequently
Move class outdoors if possible and repurpose large unused spaces as temporary classrooms
Keep class groups as distinct and separate as possible
Regularly disinfect shared surfaces
Increase ventilation by bringing in more fresh outdoor air
Filter indoor air
Supplement with portable air cleaners
Use plexiglass as a physical barrier around desks
Improve toilet hygiene and keep toilet lids closed, especially when flushing
Hold physical education classes outdoors
Replace high-risk activities (e.g., choir practice) with safer alternatives
Stagger school arrival and departure times and class transitions
Modify school start times to allow students who use public transport to avoid rush hour
Form a COVID-19 response team and plan
Prioritize staying home when sick
Encourage viral testing any time someone has symptoms, even if mild
Support remote learning options
Protect high-risk students and staff