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