Data gathered worldwide are increasingly suggesting that schools are not hot spots for coronavirus infections, according to an article in the leading science journal Nature.

In conclusions that tally with evidence presented by the Health Service Executive in relation to schools in Ireland, the Nature article finds that despite fears, Covid-19 infections have not surged as a result of the reopening of schools and childcare centres.

It says the international evidence also shows that when outbreaks do occur, they mostly result in only a small number of people becoming ill.

This again corresponds with HSE findings that in the relatively rare cases where transmission is believed to have occurred in a school setting, the average number of people infected is just three.

The Nature article was published yesterday.

It says research shows that children can catch the virus however, and shed viral particles, and that older children are more likely than very young children to pass it on to others. 

Scientists say the reasons for these trends are unclear, but they do have policy implications for older children and teachers.

Nature quotes infectious diseases epidemiologist at Berlin's Robert Koch Institute, Professor Walter Haas, who says that while schools and childcare centres seem to provide an ideal setting for coronavirus transmission because large groups gather indoors for extended periods of time, still globally Covid-19 infections remain much lower among children than among adults.

Nature says the evidence shows that even in places where community infections were on the rise, "outbreaks in schools were uncommon, particularly when precautions were taken to reduce transmission".

It points to Italy where despite numbers climbing in the community, in 93% of school cases only one infection was reported, and only one secondary school had a cluster of more than ten infected people.

Again, this mirrors the picture in schools here where, according to HSE data, transmission of the virus within schools is estimated to have taken place in just 1.5% of all schools, with an average of just three students or staff infected in these cases.

The HSE has found that in a strong majority of cases diagnosed in schools, family members are also found to be symptomatic. This indicates that the student or staff member has contracted the virus outside the school setting.

The Nature article also cites data from school outbreaks in England, which shows that out of 30 confirmed school outbreaks in June, most involved transmission between staff not students.

It quotes a meta-analysis of prevalence studies which finds researchers suspect that children - especially those under the age of 12-14 - are less susceptible to infection than adults.

Prof Haas says that "the potential to transmit increases" with age, and that adolescents are just as likely to transmit the virus as adults. He advises that when community transmission is high, teenagers and teachers should take additional protective measures such as the wearing of masks.

This is a measure that is already in place in Irish schools.

Data show that the older the child the greater the likelihood of infectiousness.

Prof Haas told Nature that it is still puzzling as to why young children seem less likely to spread the coronavirus to others.

It could be because they are more commonly asymptomatic, or it could be because they have smaller lungs.

While scientists say there is no such thing as zero transmission or zero risk, according to Nature the evidence internationally continues to point to a low risk of infection in schools, especially when community transmission is low. 

The evidence gathered by the HSE over the course of this month and last, and presented at a briefing yesterday, supports this conclusion.