When it comes to Covid-19 risk arising from schools, the emphatic message from public health specialists is that they are not significant sources of outbreaks.
That has been the consistent message from the National Public Health Team (Nphet) in Ireland to the World Health Organisation and the European Centre for Disease Prevention and Control (ECDC).
Nphet has repeatedly advised that schools are safe environments with low levels of child-to-child and child-to-adult transmission, but questions now arising are:
Is the risk still low given rampant coronavirus spread in communities at present, and evidence the so-called “UK variant”, which is present in Ireland, is up to 60 per cent more infectious?
Has sufficient account been taken of the risk of asymptomatic spread of Covid-19 in such settings?
Minister of State Josepha Madigan said on Monday the relatively low number of cases in schools in the last week before the Christmas break supported the view schools are safe. Of 3,331 people tested in schools and childcare facilities, 128 were positive (3.8 per cent) – 106 were aged under 17. Testing was conducted in 185 facilities; 37 of which were shown to have outbreaks.
Exponential growth in community spread and confirmation of the transmission characteristics of that UK variant – now in 33 countries – means much changed circumstances in less than a few weeks as the Government wrestles with whether or not to extend closures.
Dominant
Moreover, the variant may soon become the dominant form of the virus. University of Warwick virologist Prof Lawrence Young noted research indicating it is responsible for increased levels of infection observed in individuals under 20 years old.
“This suggests that the spread of this virus variant during a period of [UK] lockdown may have been driven by schools remaining open,” he added.
School outbreaks have not been a prominent feature in the pandemic, mostly because the majority of children do not develop symptoms when infected, or develop a very mild form of the disease, the ECDC declared in October.
While there is evidence of transmission from adults to children in households, there is little evidence of this in schools.
Low proportions of antibodies found in children’s blood may indicate they are less susceptible to severe infection, and therefore play a less significant role in virus spread. This, however, depends on adherence to key measures; increased physical distancing, improved ventilation, regular hand-washing and use of masks when feasible.
A key factor of Covid-19 in schools is symptomless cases. Between 30 and 40 per cent of adults are believed not to display any symptoms on the day of testing, even if they have been infected. For children, however, this figure is higher.
"It is probably more like 50 per cent for those in secondary school while for boys and girls in primary school, around 70 per cent may not be displaying symptoms even though they have picked up the virus," said Prof Martin Hibberd of London School of Hygiene and Tropical Medicine.
Disease-carriers
That is a large proportion of symptom-free disease-carriers within a population. What is not yet known is how much infection is being passed on. A definitive answer evades scientists, though there is evidence to suggest people who don’t display symptoms of Covid-19 may have lower viral loads, and are less likely to infect others.
This tendency correlates with age, so younger children have lower viral loads. As a result, they are less likely to display symptoms – and also less likely to pass on the virus.
Trinity College immunologist Prof Luke O'Neill said he did not believe schools will re-open, given soaring infection rates. "We're looking at these numbers...if we get to Wednesday, Thursday, Friday, and the numbers are even higher, I can't see the schools opening because it's another risk," he told Newstalk Radio.
It may not be a huge risk if schools are reopened but it had to be viewed in the context of numbers being out of control, he added. Additional reporting – Guardian