Children under the age of 16 accounted for 1% of coronavirus cases in the first peak of Covid-19 in England, a new study has concluded.
The authors said that their study provides further evidence for the “limited role of children in the pandemic”.
The study, led by Public Health England (PHE), comes after Boris Johnson said getting all children back to school full-time in England next month is the “right thing for everybody” amid calls to boost coronavirus testing and tracing to ensure a safe return.
Between January 1 and May 3 2020, 129,704 out of 540,305 people tested positive for the novel coronavirus – also known as Sars-CoV-2 – in England, the authors wrote in the Archives of Disease in Childhood journal.
The first confirmed case involving a child was on February 29.
Cases among children started to increase during the second week of March and peaked on April 11 2020 before declining gradually – a similar trend seen in adults.
Overall 35,200 tests were performed on children under the age of 16 and there were 1,408 cases among children aged 15 – meaning around 4% of all children tested had a positive result.
This compared to 19.1%-34.9% positive results among tested adults.
When considered in light of positive cases among all age groups, children accounted for 1.1% of all cases of Covid-19.
Just over half (53%) were boys.
The highest number of positive cases in children were among children under the age of three months – but researchers said that this was just a reflection of the higher number of tests done among children in this age bracket.
They said that young infants are more likely to have more tests done when they are unwell and parents are more likely to take them to a doctor if they are younger.
During the study period there were eight deaths of children confirmed to have Covid-19.
In four cases “another cause (of death) was identified and Sars-CoV-2 was reported to be incidental or an indirect contributor to death”, the authors wrote.
And among four children aged 10 to 15 who died, three had “multiple” other health conditions, they wrote.
The authors added: “There has been no increase in excess deaths in children aged 0–15 years until May 3 2020”.
They conclude: “The experience in England adds to the growing body of evidence on the limited role of children in the Covid-19 pandemic, with just over 1% of confirmed cases occurring in children.
“Children accounted for a very small proportion of confirmed cases despite the large numbers of children tested.
“Sars-CoV-2 positivity was low even in children with acute respiratory infection.
“Our findings provide further evidence against the role of children in infection and transmission of Sars-CoV-2.”
Previous research has implied that lower infection rates among children may be due “lower expression of the cell surface enzyme ACE2 in the nasal epithelium of children compared with adults”.
ACE2 is a protein on the surface of cells to which Sars-CoV-2 binds, and can be found on the cells on the inner lining of the nose. Previous research has implied that the lower risk in children may be down to the fact they have lower expression of this enzyme in the inner lining of their nose.
The authors of the current paper say that a “key” unanswered question remains whether children without symptoms might be contributing to community transmission of the virus.
But they point to other research which shows low infection rates among children and a separate study which found that among household infections children were “never the first to be infected or to be the source of infection in the household”.
The authors, which include experts from PHE, the University of Oxford, the Evelina children’s hospital, King’s College London and the London School of Hygiene and Tropical Medicine, concluded: “England is currently nearing the end of the first peak of the Covid-19 pandemic.
“Consistent with other countries, children account for a very small proportion of confirmed cases and have very low case-fatality rates. Despite the large number of children tested, only 4% were positive for Sars-CoV-2.”
Lead author Dr Shamez Ladhani, from PHE, added: “It is still not clear why young children have such a low risk of infection compared to older children or adults. One theory is that, compared to adults, children have fewer ACE2 receptors which the virus can bind to in cells that line the respiratory tract.
“The way the immune system reacts to the virus is also likely to be different in children compared to adults.
“Whilst these numbers are reassuring for children, they include a long period of complete lockdown where children were less likely to have been exposed to the virus.”
And he cautions: “We need to remain vigilant as the lockdown eases and children have increased contact with other children and adults in the coming weeks. In particular, we need more information about asymptomatic infections and silent transmission.”
PHE said that an analysis of Covid-19 cases in educational settings in England, and the preliminary results of its nationwide study of antibody prevalence in schools, will be published “in the coming weeks”.
Commenting on the study, professor Russell Viner, president of the Royal College of Paediatrics and Child Health, said: “These data are high quality and very useful and confirm international evidence that children and young people as a group are little affected by this virus, even showing a slight reduction in total excess deaths.
“Any death of a child is one too many, however even the extremely low Covid-related death rate is an overestimate as Covid-19 infection appeared incidental in half those who died.
“Testing of symptomatic cases can be misleading about the chances of transmission, as children are much less likely to be symptomatic than adults, however these data provide another part of the jigsaw that together tells us that children play only a minor role in this pandemic.”
Dr Mike Tildesley from the University of Warwick, added: “These results provide further supporting evidence that the reopening of schools in September should represent an extremely low risk to any individual child, though it is important to recognise that, despite these low numbers, we would expect that children may play a role in the transmission process.
“With this in mind, the vast majority of parents should feel reassured regarding the safety of their children when schools reopen, though given the likely role of infected children in transmission, parents and teachers with underlying health conditions may need to take precautions in order to minimise their own risk over the coming months.”