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