School COVID clusters are rare – so what can we learn from the Al-Taqwa outbreak?

Doug Hendrie

5/08/2020 4:27:33 PM

In short: Close schools when community transmission is high, open cautiously when it is low, according to epidemiologists.

Al-Taqwa College
With 183 cases, the Al-Taqwa cluster is Victoria’s largest and second in Australia to only the Ruby Princess cruise ship cluster. (Image: AAP)


Something rare happened in early July.
A major coronavirus cluster developed at Al-Taqwa College, a large primary and high school in outer-Melbourne.
With 183 cases, the cluster is now Victoria’s largest and second in Australia to only the Ruby Princess cruise ship cluster of almost 700 cases.
But school clusters are comparatively rare among such super-spreading events. An open database of more than 1200 such clusters from around the world lists only 17 centred around primary or high schools. They are much more likely to occur in aged care homes, meatworks, workplaces and prisons.
That comparative rarity is behind Australian Health Protection Principal Committee (AHPPC) advice that schools have a ‘relatively low risk’ of transmission, assuming social distancing and hygiene measures are in place.
Authorities across the world have tried to minimise school closures where possible, due to the large flow-on impacts on education, parents’ ability to work, and the fact children are at much lower risk of developing serious forms of COVID-19.
The coronavirus-stricken US is set to reopen its schools despite the virus running rampant. The country’s Centers for Disease Control and Prevention (CDC) states on its website that the ‘best available evidence indicates if children become infected, they are far less likely to suffer severe symptoms … [d]eath rates among school-aged children are much lower than among adults’. 
However, Victorian schools are now shifting en masse to remote learning as part of the state’s new stage four lockdown aimed at shifting stubbornly high infection rates, with childcare also due to largely close for the first time in the pandemic.
And there is the Al-Taqwa cluster. Is it a warning sign for schools more broadly? Or is it simply bad luck, with an index case able to spread widely before being detected?
Victorian health authorities believe the cluster began with a teacher who had attended a large family gathering, according to The Age.
But the state’s Chief Health Officer Professor Brett Sutton has also said there is an epidemiological link between the school cluster and the inner-Melbourne public housing towers being forced to enter hard lockdown due to a major cluster, with many students from the towers being bussed to the school daily.
Al-Taqwa has around 2200 students, making it the largest Islamic school in the state.
School staff have defended their approach to hygiene. Teacher Salma Harrabi noted on the Al-Taqwa Facebook page that the school had undertaken social-distancing measures, with hand sanitisers in class and temperature checks before entering the school.
‘We did social distance and what happened was very unfortunate,’ she wrote.

Questions remain over exactly how many cases are directly linked to the school, given the first known case connected to the school was notified positive on 27 June, the day after term two ended.

Parents and staff were notified immediately, and the school closed and has not reopened for face to face learning.  

School sources told newsGP the school had gone above and beyond DHHS requirements, such as introducing mandatory on-arrival temperature checks for staff from the end of term one and students from the end of term two, and had followed all department guidance on contact tracing, securing the site and introducing further precautions.  

The source said that while some infections may have incubated during the school holidays, subsequent infections could not have originated at the school as it was closed.
GP Dr Hanna El-Khoury personally treated students and family members from five Al-Taqwa families who had the coronavirus. He told newsGP of his frustration at providing the wrong advice to students because he was unaware the cluster was developing. 
Dr El-Khoury told one young symptomatic patient who had received a negative COVID-19 test that it was likely just a cold.
‘If they were in close contact, they should have stayed away for two weeks – regardless of the COVID test,’ he said.
‘There was a missed opportunity here to control it. I didn’t know it was a cluster.
‘I had no information from the school or the government.’
Dr El-Khoury believes the cluster went under the radar. He said some family members who were confirmed cases said they did not want people to know they were sick with the virus.
‘There is a stigma to infection,’ he said. ‘People don’t want others to talk about them so they hide it.’
What can we learn from the school cluster?
University of New South Wales epidemiologist Professor Mary-Louise McLaws told newsGP it is still accepted that young children are less likely to acquire the coronavirus.
What remains unknown in the Al-Taqwa outbreak, she said, is whether students acquired it through their family members, given the virus is particularly common in nearby suburbs, or whether it was school-acquired.
‘If it follows international trends, it will be coming from family clusters,’ Professor McLaws said, though she pointed to the complex exception of the Jerusalem high school outbreak where clusters developed after class size restrictions were lifted.   
Professor Sutton told The Age that Al-Taqwa appears to differ to most school clusters, where the virus tends to be acquired in family settings.
‘There seems to have been transmission in the school that was quite substantial,’ he said.
The virus spread among senior students at a similar rate to that of adults.
‘They are older kids, they tend to have more transmission that is akin to adults if they’re not doing the physical distancing appropriately,’ Professor Sutton said.

Victorian Chief Health Officer Professor Brett Sutton said there is an epidemiological link between the school cluster and the inner-Melbourne public housing towers forced to enter a hard lockdown. (Image: AAP)

University of Western Australia epidemiologist and biostatistician Dr Zoë Hyde told newsGP that while schools are relatively safe when community transmission is low, they are a greater risk if the virus begins to circulate widely, as Victoria is now experiencing. 
‘Risk is very much a function of community transmission,’ she said.
‘If it is high, we will inevitably see school outbreaks. If it is low, then schools are probably a low-risk environment.
‘We have only recently begun to experience sustained community transmission in Australia, and we are now seeing the implications of that.’
Primary schools appear to be lower risk, with evidence for ‘significantly lower susceptibility to infection’ for children aged under 10. There is some evidence of ‘robust spread’ in high schools and more limited spread at primary schools, according to a new Medrxiv preprint evidence review by epidemiologists Professor Marc Lipsitch and Dr Edward Goldstein, and infectious diseases researcher Dr Muge Cevik.
‘Opening secondary/high schools is likely to contribute to the spread of SARS-CoV-2, and, if implemented, it should require both lower levels of community transmission and greater safeguards to reduce transmission,’ they conclude.
However, their conclusions have been challenged by University of California Professor A Marm Kilpatrick, who argues the data do not support the ‘strong claim’ of lower susceptibility in children.
‘I’d argue we cannot make any claims about susceptibility [because] we can’t separate susceptibility from contact,’ he wrote on Twitter.
‘Regardless of which is correct, I think all epidemiologists would still recommend the same course of action to re-open schools safely: We need to reduce community transmission and put measures in place to reduce risk in schools – masks, distance, ventilation, cohorting, etc.’
Dr James Best, Chair of the RACGP Specific Interests Child and Young Person’s Health network, told newsGP it is important to avoid knee-jerk reactions to school clusters, given many other clusters in meatworks and aged care facilities.
‘When a cluster occurs in a school, you need to find out if it is occurring inside or outside the school,’ he said. ‘There have been similar arguments about how healthcare workers acquire COVID.
‘People see a cluster and say, why are we still sending our kids there? We need to be wary of the emotional aspects of this.
‘Parents get worried about sending their child to school and you can get a panic run where no one wants to send their kids to school. Then they come to their GP asking to have a note saying they don’t need to go.
‘Fear is a big factor, but we need to allow our public health officials and researchers to do their jobs. It can get very emotional because there are big stakes here, but we have to put our faith in those who know how to analyse this data.
‘There is the virus risk, but also there are job losses, unemployment, mental health. These are complex issues.’ 
Dr Best said figuring out the likelihood of school clusters is ‘very complex decision-making’, taking into account the asymptomatic rate in children, whether they acquire the infection from family or the school, and the risk to teachers, all balanced against the risk to society from closing schools.
Epidemiologist Professor Allen Cheng points out in The Conversation that much of the thinking around the low risk for school transmission is based on a report following up school cases in NSW in the first wave of the pandemic.
That report found that, of the 18 confirmed school cases, all had the potential to transmit the virus to 863 close contacts – but no staff member contracted the virus, while two students may have acquired it.
Dr Hyde said any analysis of the Al-Taqwa cluster will be speculation until a detailed epidemiological investigation is published.
‘It could be relatively straightforward like the Jerusalem high school. Alternatively, it may more closely resemble the Marist College cluster in New Zealand, in which community events held at the school likely contributed to the outbreak,’ she said.
‘In this respect, the role of schools as community hubs is important to consider.
‘When community transmission is low, non-pharmaceutical interventions to control the epidemic, such as testing and contact tracing, are highly effective. Transmission chains can be rapidly interrupted, and the likelihood of the virus being introduced to the school environment is low.
‘In contrast, if community transmission begins to rise, contact tracing can be slowed or over-burdened to the point where it becomes impractical. As the number of undetected cases rises in the community, so too does the probability of an introduction to the school environment. Under these conditions, we’re much more likely to see super-spreading events.’
Dr Hyde believes the weight of evidence is now suggesting that children and adults seem ‘equally vulnerable’ to infection, given the right circumstances.
‘Many studies which suggest otherwise have important limitations, such as being conducted during widespread school closures or at a time when the virus was initially circulating among adult travellers and their contacts,’ she said.
‘Additionally, children are more likely to be asymptomatic or have mild disease, and have gone under the radar a bit with testing.
‘Young children might possibly be a little less likely to transmit the virus than adults, but the high number of contacts children have in schools is vital to consider. This might offset any advantage.
‘As community transmission has grown and the virus has spread into younger age groups, we are witnessing outbreaks in day care centres and schools. This seems to dispel any notion that children are less susceptible to the virus.
‘I find it plausible that older children might transmit the virus more readily than younger children, but we cannot overlook the large number of contacts that young children have.
‘I suspect all schools are high-risk environments when community transmission rises.’
Dr Hyde believes the new risk-reduction guidelines for schools recently released by the Harvard TH Chan School of Public Health have merit and could be considered for Australian use.
These guidelines state, ‘scientific evidence indicates that risks to students and staff can be kept low if schools adhere to strict control measures and dynamically respond to potential outbreaks’.
‘I advocate for school closures during sustained community transmission, and cautious school reopening with behavioural and environmental measures in place when community transmission has been suppressed,’ Dr Hyde said.
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