Schools are not major transmission sites for Covid, say health chiefs 

Prof Philip Nolan said there is 'considerable evidence' that with 'effective mitigation measures in place', schools are not major transmission sites.

Health chiefs have reiterated to parents that schools are not major sites of transmission for Covid-19.

Both Professor Philip Nolan, chair of the Irish Epidemiological Modelling Advisory Group, and Chief Medical Officer Dr Tony Holohan sought to reassure parents as the thousands of children returned to the classroom today.

Prof Nolan said there is “considerable evidence” that with “effective mitigation measures in place”, schools are not major transmission sites. This is affirmed by the experience of public health doctors who supported the safe opening of schools in Spring 2021, he said.

However, Prof Nolan admitted that the Delta variant does pose a new challenge to opening schools this time.

“We have no experience of opening schools with the Delta variant and such high levels of circulating virus in young adults, adolescents and children,” he said in a social media post.

“While Delta is more transmissible, this does not mean that the modes of transmission, or the relative importance of direct contact, droplets, short-range aerosol, long-range aerosol and fomite transmission are different for Delta and Alpha.” 

He said that when in-school transmission has occurred, “it tends to be amongst friendship groups and in high-contact situations”.

Prof Nolan highlighted that the Delta variant does not transmit differently to other variants, but it transmits more efficiently.

“It is reasonable to assume that mitigation measures that were effective against Alpha will also be effective against Delta, though they need to be strictly observed, and the situation monitored,” he said.

The transmissibility of the Delta variant is a “concern”, Prof Nolan said, but he said there were equal concerns “about the opening of schools with a new, more transmissible variant, the Alpha variant” last March.

He said that if a variant "is twice as transmissible it doesn’t necessarily mean mitigations are half as effective.

"Many mitigations create a threshold, and transmissibility must exceed that bar for that mode for infection to occur.

“Incidence in children has been lower than the population average, and while it is difficult to allow for under- and over-ascertainment, there is considerable international evidence that younger children are less susceptible than adults.

“School openings and closures to date in Ireland have had minimal effect on incidence in the population as a whole and in children and adolescents of school-going age.” 

The CMO said: “Our data clearly shows that, to date, the school environment was not a major source of disease transmission.” File picture: Denis Minihane.

Prof Nolan said while there have been “transient increases in incidence” after each re-opening, these have not been sustained.

Modelling from Technological University Dublin “suggests that any increase in incidence in children after school reopening depends on the susceptibility of children, effectiveness of mitigation in schools, and whether adults increase their contacts/return to work.” 

CMO Dr Tony Holohan echoed Prof Nolan’s statement, saying “our data clearly shows that, to date, the school environment was not a major source of disease transmission.” 

Dr Holohan reassured children and parents that “considerable preparations” have been made to allow schools to reopen safely.

He called on students to follow the protocols operating in their schools and urged them to wash their hands regularly.

Dr Holohan urged parents to “please keep in mind the symptoms to look out for and do not send your child to school if they display any of them, instead help them to isolate and contact you GP for advice and arrange a test if appropriate.

“I would also urge caution when participating in activities with classmates outside the school environment, which have proven to be settings where outbreaks and transmission in children have occurred in the past.

“This will help to prevent further transmission and potential outbreaks.”

The CMO's comments come as a further 1,293 cases of Covid-19 have been recorded today.