In the northern hemisphere children are returning to school, and in countries where COVID-19 is still spreading this is a serious concern. There is still a great deal we don’t know about the SARS-CoV-2 virus, although we are rapidly learning. One big question is the role that children play in the pandemic. Specifically, we need to know the risk of children catching the virus, if they do what is the risk they will develop clinical COVID-19 (as Clay discussed several months back – the risk seems generally low but there are reasons to be concerned), and either way what is the risk they will pass on the virus and become a vector for spread?
A recent UK study adds some information to these questions. The study is being reported as “reassuring” but only relatively so. The study looked at 651 children admitted to the hospital with confirmed SARS-CoV-2. Of these children 18% were admitted to critical care and 1% died. This is less than the figures for adults (27% of those admitted to the hospital with COVID die), but I’m not sure parents would be “reassured” by a 1% mortality rate. However, they also found that these children who were admitted to ICU or died were far more likely (42%) to have an underlying medical condition – “the most common ones being illnesses affecting the brain and nervous system (11%), cancer (8%) and asthma (7%).”
Also, 11% met the WHO MIS-C criteria – this is a multisystem inflammatory syndrome in children. This tended to occur in older children in this study. MIS-C is still a bit mysterious, but it appears that in a subset of children with COVID-19 they develop an autoimmune syndrome with inflammation affecting different organ systems. This can be a serious and even life-threatening illness. In general we are finding that the immune system’s reaction to COVID-19 is often more dangerous than the infection itself, especially in severe cases. There is something about the virus which affects certain people, probably due to the genetics of their immune function, in a way that triggers an extreme immune reaction.
The study also found that the poor and minorities were more likely to be admitted and die from the disease.
In terms of the susceptibility of children to COVID, it does appear to be much less than adults – but it’s not insignificant. This study does suggest that it would be relatively safe for the children themselves to return to school, with the caveat that children with serious underlying medical conditions probably shouldn’t.
What about the question of whether or not children can be asymptomatic carriers of the virus, which could play a huge factor in spreading the pandemic as children return to school? Here we have a recent study from South Korea, which is the opposite of reassuring. South Korea has an extensive program of contact tracing, which follows infected people with serial testing until they clear the virus. This provides a great opportunity to trace how the virus spreads and who is spreading it.
They found that children can have the SARS-CoV-2 virus detectable in nasal swabs for up to three weeks, even if they are asymptomatic. Further, they found that family contact of children currently attending school were the most likely contacts to contract COVID. Younger children 0-9 years old who were currently not in school were the least likely to pass on the virus.
A recent comprehensive review of the research so far also finds that children are asymptomatic carriers of the virus, and that they generally have high viral loads. High viral loads generally translates to being highly contagious – there is more virus to shed and spread to others. Further, when children are symptomatic they tend to have mild non-specific symptoms, which can easily mimic a cold. So COVID may be harder to detect in children.
We don’t know exactly what the risk is of asymptomatic children passing on the virus, but this study suggests it is not negligible. This, of course, would be the worst-case-scenario for opening schools – that children can be asymptomatic carriers and spreaders of the virus, bringing it back to the adults in their home. Meanwhile, the American Academy of Pediatric is urging a “safe” return to school this fall, especially for younger children. They are concerned about the learning and socialization of children, especially since we have essentially already lost a semester. How do we balance these two concerns?
In countries where the pandemic is still spreading, like the US, we need to carefully consider our strategy for returning children safely to school while containing the pandemic. Here the South Korea model may be instructional – use extensive testing and contact tracing to detect any spreaders and isolate them quickly. No such system is in place in the US, however.
Basic precautions will help to some degree. Many schools are reducing the number of days children will be in school and instituting rules for social distancing, mask wearing, and hand hygiene. This will help. Younger children may find it harder to comply, but they are also less likely it appears to contract the virus and spread it in any case. Shifting as much as possible to online learning is also one strategy.
Many schools, however, lack the resources to fully implement a COVID strategy for this fall. This is all a massive experiment, and we may not like the outcome.