School closures should be used as a last resort to control the spread of Covid-19 according to researchers as a new study found there was a limited spread of the virus in schools in Ireland during the pandemic.
The study by HSE personnel found that less than 3 per cent of close contacts in school with people infected with the Sars-CoV2 virus during the 2020-21 school year had tested positive for Covid-19.
“The school outbreaks that we detected were generally small with 92 per cent of outbreaks each comprising less than 10 cases,” said one of the report’s authors, Ciara Kelly of the HSE’s Health Protection Surveillance Centre.
Dr Kelly said the study’s findings showed schools were low-risk settings for the spread of the infection and school closures should be avoided because of the consequences of reduced formal education and socialisation during children’s formative years.
The study, which is published in a European journal on infectious diseases, Eurosurveillance, acknowledged that the extent to which the virus is spread in schools remains somewhat unclear.
However, it noted that other research had indicated that the spread of Covid-19 in school settings had lower levels of transmission than in the general population.
In addition, it pointed out that extensive transmission of the infection in school settings had been largely suppressed by strict prevention and control measures.
They had been introduced at the beginning of the 2020-21 school year with confirmed cases of Covid-19 advised to self-isolate for a period of 7-10 days.
Close contacts were kept away from school after their exposure to a confirmed case but could return to school if they tested negative for Covid-19 after 10 days and remained asymptomatic.
The study identified 21,727 confirmed cases in 5-18-year-olds in Ireland during the 2020-21 school year, representing 2.4 per cent of that age cohort.
They accounted for 18.2 per cent of all notified Covid-19 cases over the period rising from 15.5 per cent during the first term to 23.9 per cent in the third term.
The study said the increase could be explained by the emergence of more transmissible variants of the disease.
In total, 100,474 close contacts were tested in 1,771 schools over the same period, with 2,373 confirmed as positive.
It equated an overall positivity rate of 2.4 per cent among all school close contacts.
The highest rate was recorded in special schools at 3.4 per cent and the lowest in post-primary schools at 1.8 per cent with primary schools recording a rate of 2.5 per cent.
Overall students had a significantly higher positive rate than staff at 2.4 per cent compared to 1.8 per cent, with even higher rates for students in primary and special schools.
In contrast, staff had higher positivity rates in secondary schools, although the difference was not considered statistically significant.
Students represented 90.5 per cent of schools close contacts with 9.5 per cent made up by staff.
The study noted that 832 outbreaks of Covid-19 in schools had been notified in relation to 3,665 cases between August 2020 and June 2021.
In addition, 18 schools had been closed on the advice of public health officials as the whole school population in such cases had been identified as close contacts.
The study said 92 per cent of outbreaks involved less than 10 cases with 34 per cent comprising just two cases.
It also revealed that 44.7 per cent of all schools reported at least one confirmed case of Covid-19 who attended school during the infectious period with close school contacts identified.
The study said making direct comparisons between its findings and the results of international studies was challenging although the close contact positivity rate in Ireland was consistent with the findings of similar research conducted in Norway, Italy, Germany, Australia and the US.
It claimed the higher positivity rate in special schools could be explained by the greater educational and personal care needs of students in such schools which meant they had longer contact time with staff.
It said the significantly lower rate of Covid-19 among school staff identified as close contacts could be due to them being more effective in maintaining control measures such as physical distancing compared to students. In addition, it noted staff were required to wear face coverings in all schools.
The study said information on compliance by schools with control measures should be a priority for future research.
Dr Kelly said it was possible that the extent of the transmission of the virus in schools might have been overestimated where pupils might have become infected from social activities or transport.
While the majority of close contacts had tested negative, she said such students had lost substantial education time which was compounded by the mandatory closure of all schools in the Republic in early 2021 as a result of the third wave of the pandemic.
“A consistent measure in international literature and guidance is that school closures are not primary drivers of Sars-CoV-2 transmission, with any potential benefits of school closures in reducing community viral transmission being far outweighed by the resulting harms to children,” said Dr Kelly.
In the event of future pandemics, she said the harms and benefits linked to disrupted education must be carefully considered before reflexively closing classes or schools, while there should also be maximum uptake of any vaccination and a high level of compliance with control measures.
