Right now many of the world's children are beginning to return to school after extended lockdowns due to COVID-19. Not surprisingly, precisely how and when to permit children to return to schools has led to lively public debate. The concern, of course, is that children could be put at risk from the infection and become "super spreaders" for community transmission. But what does the evidence suggest so far?
Well, research is ongoing and it will take some time before there is a definitive picture. However, research is rapidly taking shape, and the early findings are both interesting and encouraging.
This blog post focuses on answering the following three key questions by examining the current research emerging globally on the novel coronavirus:
1. How likely are children to become infected?
2. How likely are children to spread the disease?
3. How high is transmission risk in outdoor settings?
It also looks more closely at whether outdoor education could be an essential part of the solution in the "new normal" within schools worldwide. It relies on the available science and not on opinion. As with anything in science, as new information and evidence emerges, we must update our understanding and knowledge frameworks. Science never stands still and nor should it. So here goes...
1. How likely are children to become infected with COVID-19?
Overall, children appear to be less likely to become infected than adults. A review of international studies by the Dutch National Institute for Public Health found that the percentage of children among the confirmed COVID-19 patients is small, varying from 1% in young children and up to 6% in older children. In China and Japan, tracing studies give a similar picture. One Chinese study found that adults aged 15-64 were three times as likely to be infected by others in their household than children aged 0-14 were, while adults aged over 65 were at even greater risk. In addition, a closer look at Iceland, where large-scale testing has been carried out, a population screening programme did not reveal a single infected child under the age of 10 (out of a total of 100 confirmed cases).
Taken together, the lower infection rates and typically milder symptoms in children mean that the disease is affecting the child population far less severely than for older age groups. The UK Office for National Statistics mortality dataset – probably the most reliable source of information on fatalities – shows that March 2020 saw just one Covid-19 related child fatality (in fact aged between 15 and 19). The chart below shows the ONS figures for different age groups.
2. How Likely Are Children to Spread the COVID-19?
Studies are also beginning to emerge on the likelihood of children spreading COVID-19. Of course, anybody who has worked with children in schools or other childcare settings, will know first hand that kids are often very effective at spreading bugs and other viral infections, especially illnesses like colds and the flu. Therefore, it is prudent to be very cautious when examining how likely children are to spread the coronavirus, and whether it is safe to permit children to return to education settings.
So far, studies of household clusters of infection show that children are the "index case" (or the likely original source) in only around 5-10% of cases. In a sample involving 55 cases, the Dutch review cited above found no records of spread from children under the age of 19, and stated that children “play a much smaller role in the spread than adults and the elderly.” In Sweden, schools and childcare providers have not been closed during the coronavirus outbreak, making Sweden an interesting case study. Sweden's National Public Health Agency states that none of the outbreaks it has seen so far have been linked to schools or children. Similarly in Australia, very low rates of infection in school children and low rates of spread were reported in a contact tracing study following up on 18 cases from 15 schools in New South Wales. They reported no cases of adults becoming infected from children, although it must be emphasized that absolute numbers are low.
School and childcare settings were closed early on in the outbreak in many countries, so it is possible that this could have led to children appearing less often as index cases. However, as countries move out of lockdown and reopen schools and childcare settings, it will be critical to study this more closely.
3. How High is Transmission Risk in Outdoor Settings?
While the research base for COVID-19 transmission routes is still in its infancy, the emerging picture is that outdoor airborne transmission is rare compared to transmission via close personal contact, especially in indoor settings. One Chinese study found that 80% of outbreaks were associated with the home environment. Typically, in these cases, a household member became infected via community transmission and infected other people living in their home. One third of cases were linked to public transport (note that many outbreaks were linked to more than one location). Out of 318 outbreaks, only one case was linked to an outdoor setting.
While not peer reviewed, an in depth analysis by Erin Bromage Ph.D., a comparative epidemiologist at the University of Massachusetts Dartmouth, reveals some fascinating insights. It discusses documented case studies of multiple spreading events around the world and argues that the most important factor is time spent in proximity to infectious people. She concludes that environments most likely to lead to outbreaks are "enclosed with poor air circulation and a high density of people." Based on the available data it appears restaurants, workplaces, choir, indoor sports, birthday parties and funerals are places where risk of transmission is highest. Importantly, of the countries performing contact tracing properly, only a single outbreak has been reported from an outdoor environment (less than 0.3% of traced infections.)
What's the Take Home Message?
It is still too early to state with confidence the level of risk for children becoming infected with the coronavirus, or whether children are effective spreaders of the illness. However, the early signs are encouraging and suggest that getting children outdoors could be one way to reduce transmission risk in schools and childcare settings. In the coming months, more research will emerge and we will get a better picture. In the meantime, do your part and wear a mask to reduce what you release into the environment. It will help everyone, including your own school or business.
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