NB Throughout this piece “younger children” refers to children aged 11 and under.
As England enters another lockdown on 5 November 2020 the one key difference with the first lockdown is that schools and universities are remaining open.
For schools there will always be the fine balance between the detrimental effects on children of repeatedly pulling them out of the school environment versus the risks of COVID-19.
(Click here to read more about the effects of school closures on children and here for an overview written in September 2020 on the reopening of schools and universities.)
We don’t yet have enough data to know how much COVID-19 is caught outside of the school and taken into the classroom as opposed to caught in school and then taken home but as more studies are done it seems that younger children are unlikely to be spreading the virus.
Schools, in theory, provide an ideal setting for virus transmission with larger groups gathered indoors for long periods of time. However despite this, COVID-19 infections have remained much lower in younger children than adults.
Walter Haas, an infectious diseases epidemiologist at the Robert Koch Institute in Berlin, reports that cases amongst children in schools “seem rather to follow the situation than to drive it.” (1)
A recent review of schools world-wide supports his view. (2)
In Italy, 65,000 schools reopened in September 2020 when case numbers in the community were already raising yet four weeks later only 1,212 reported cases of COVID-19 and of those 1,212 schools 93% had just one case. (3)
Similar findings in Australia showed outbreaks in schools were rare and, of those that did occur, around 65% involved just one case. (4)
In England, the study of 30 school outbreaks in June 2020 showed that just two were caused by child to child transmission. Researchers also found a strong correlation between the background community infection rates and school outbreaks. In other words, the more cases in the local area, the more likely cases would occur in its schools. (However, schools were not fully open to all year groups in June 2020 so these findings should be viewed with caution.) (5)
Similar patterns were also seen in the United States where schools that reopened in areas with high background infection rates in the local community were more likely to have outbreaks than those in areas with fewer infections. (6)
Whilst younger children are the least susceptible to COVID-19 infection, this drops away with increasing age. Studies in the USA have found that children in the age bracket of 12 to 17 years have twice as many infections as those aged 11 and under. In the 12 to 17 year olds the rates are highest in the older teenagers compared to the younger teenagers. (7)
Teenagers and teachers are more likely to transmit the virus so they, rather than primary school children, should be the target of measures such as mask wearing in communal areas, strident social distancing and perhaps reverting to on-line learning if community cases are at a critical high.
We don’t yet know why younger children are less likely both to have COVID-19, and then to pass it onto others, especially as they are potent spreaders of coughs and colds.
Various theories could explain why they are not playing a major role in the pandemic but known are proven.
Children’s smaller lung capacity may mean they carry a smaller viral load and are therefore less infectious to others.
The coronavirus attaches itself to human cells through a structure on the cell wall known as an ACE receptor. Research is ongoing into the role of ACE receptors in COVID-19 and specifially in people with a BAME background. BAME people have a higher than average numbers of these receptors and it is possible this is why they are also more susceptible to COVID-19. (Click here to read more on this topic.)
In contrast children have fewer ACE receptors than adults so this could be protecting them. (8)
Most younger children will have received their childhood vaccines through the NHS vaccination programme prior to starting school. Researchers are exploring if it is possible that these vaccines are in some way protecting them against COVID-19, perhaps because they have received them more recently than teenagers and adults. (9)
On a similar theme, there is some evidence to suggest that people who have been immunised against TB (tuberculosis) have a degree of protection against COVID-19. (10)
The general uptick in cases seen since September 2020 may not correlate with the schools reopening at all. The increase in rate could have been caused by people returning from summer holidays overseas. Travel is a known risk factor for COVID-19 and could be the underlying reason. (11)
Whilst nobody is disputing that cases of COVID-19 have risen steeply in older teenagers and young adults in recent months, current evidence suggests that schools are not the main driver of this. (12)
