Covid-19 transmission

Is it safe to reopen schools in September?

Is the concern protecting childen or adults?

One of the most important decisions in managing the Covid-19 outbreak has been the decision whether, and by how much, to open schools.  The UK government has announced their intention to make this a priority in terms of lifting of lockdown measures.  In this post, I review the available data that could inform this decision and  include  the results of a computer simulation study published in last week’s Lancet.  I conclude a successful return to full education is possible but this would require a major shift in approach to the control of the pandemic.  

First the background epidemiology of Covid-19 in children

Much is well known, although there are limits to the available information as there are few really high-quality studies in children so far.  These are the key findings however:

Children have the same overall rate of infection as adults

  • In the UK, repeat testing of a random sample of 20,000 households showed that 0.3% of children aged 2-11 had a positive swab test in the period 26 April to 27 June, ie had current evidence of the virus.  This was very close to the percentage in all other age groups
  • In a study in July from Spain, around 4% of those aged 0-19 had a positive antibody test – a measure of ever having Covid-19 – which was not much lower than the 5% rate seen in adult groups. 

Children have the same risk of becoming infected if exposed

  • These rates of  infection in children and adults  are related to their likelihood of exposure to an infected person 
  • A separate question is thus whether if exposed to the same risk, eg a household contact, do the children have the same risk of being infected ? 
  • A study from Barcelona in June found the rate of infection in household contacts of an infected person was around 18%, and was the same in children as in adults.

Outbreaks in school and other settings do occur

  • There are many instances of major clusters of cases in childhood settings
  • One example was 153 cases in a school in Jerusalem
  • A second example was cases in an overnight summer camp in Georgia, USA when 260 out of 344 tested positive

Children have milder disease 

  • Only 5 children have died from Covid-19 in UK.  As a comparison there were 16 deaths in children in the influenza epidemic in 2017/18
  • Fewer than 80 children in the UK were sufficiently ill to require admission to an intensive care unit (by the end of July).  This is compared to 13380 adults 
  • In the Barcelona study mentioned above, almost all (99%) of the children  had either no symptoms or minor symptoms

Is being in contact with an infected  child less of a risk to an adult than being in contact with an infected adult?

  • This is an interesting question  and obviously relevant to schools opening.  
  • There is no definitive answer but some indirect data which is inconclusive 
    • A German study found that the concentration of virus in swab samples was the same in children as in adults 
    • The Barcelona study showed that children who are infected carry the virus for a shorter period than adults.  (Note: this might be due though to the milder disease in children)  

Where do we go from here?

  • The question around school opening clearly  is not: “Are children at increased risk?”.  They are at the same risk of getting infected as adults but for them the disease is likely to be trivial.
  • Thus, the societal question is: “What is the increased risk to vulnerable adults from being exposed to children who return to school?” 
  • This raises the interesting philosophical question as to how society values the lives and general well-being of children and adults
  • The Denmark model of effective physical distancing has been held up as a model for school reopening, whereas others have said even this is too risky.

What does the Lancet study this week argue?

  • An international group of researchers developed a computer model based on a series of assumptions given current social distancing behaviours.  
  • Opening schools full time could be done without risk of a major increase in the epidemic but only if
    • 75%  of all individuals who are symptomatic are tested
    • 68% of the contacts of those who are positive are traced
    • All contacts who test positive are isolated
  • This is a difficult ask

Is there an alternative strategy?

  • One way out of this is a step change in mass testing, possibly of all school children on a regular basis  – this is now being actively explored
  • We will need cheaper tests that are simpler to process  
  • Tests are already being developed  that could be done at scale for as little as $1 and give a result in 40 minutes
  • Indeed, there are tests that can be processed locally without being sent to a specialist laboratory

Go for sewage!

  • Infected individuals, including those without symptoms, may shed virus in their stools even when the swab test is negative
  • The National Wastewater Epidemiology Surveillance Programme is screening sewage with the aim of identifying local outbreaks earlier 
  • This system is currently being tested at  wastewater treatment plants.  If this technology could be applied  at the level of institutions such as schools, that would  be a rapid and efficient way of identifying if there was a cluster of cases in that school 
  • If this was the case,  that would be a useful trigger for all the pupils to be tested 

6 replies on “Is it safe to reopen schools in September?”

Thanks Alan for your very informative updates.
I am Chair of Governors at a local primary School. I am in awe of the work that has been done to keep school open and safe all through this time. Our 10 year old granddaughter was thrilled to go back to school In July but also attended for a couple of days in May when both her parents( key workers) were in work at the same time.
September will be interesting but I have faith in the Head and staff that things will be sorted.
None of the staff( who belong mainly to the troublesome Union) refused to work and all staff have worked very hard keeping the children engaged in many different ways.


Thank you Krys. Do feel free to share widely as I think there is so much in the debate that is confusing and if I have helped to rescue this and provide some reassurance that would be useful


But ultimately Alan you are giving a definite maybe or in fact given the conditions for a relatively “safe” return that you cite, the answer is no …..since almost none of the conditions you describe will be available in September. If I were still a headteacher only if I could guarantee class sizes of 1:15 or less would I be opening very slowly with a combination of staggered attendance, social distancing and masking and distance learning. 30 secondary school kids in the same class and small British corridors jam packed with kids in between lessons coughing and sneezing from October onwards would be a recipe for disaster.

a complete return to school in the secondary system would be irresponsible.


I’m an epidemiologist and not a politician but we are faced with a situation that has no end unless there is a successful vaccine, perhaps sometime next year. A combination of political will, logistic expertise given the technological advance in testing, regular testing of children has to be considered


My son in law contracted Covid 19 in April and it took him many months to shake it off
In contrast, his wife and most of his children got a very mild dose and were fully recovered within 2 weeks
The remaining children probably got it but showed no symptoms
Is this a classic case of herd immunity?
My personal opinion, is that the risk of children picking up infections in school and being seriously ill seems to be quite slight, and is more than outweighed by the benefit of returning to school


Your family’s experience is very much reflected generally, the much lower likelihood of severity in children compared to adults, and for reasons, not fully understood, the grate severity in male, compared to female adults. Herd immunity is a different phenomenon. A the virus spreads from person to person, as the number who have had the infection and hence immune (or in the future been successfully vaccinated) the virus finds it harder to find people who are still susceptible. When the the level (ie % )of population of immunity in the population gets to a level that essentially the virus is too isolated to easily find new people to infect, then that population has achieved ‘herd immunity’. At that point an epidemic cannot take hold. The level for herd immunity differs from virus to virus but typically is around 70%


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