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As schools in Vermont and across the country prepare to reopen, it’s clear that children who do get the coronavirus are far less likely than adults to get severely ill. What is less well understood is the role they play in passing Covid-19 along to others.
A growing — albeit still quite limited — body of evidence offers hope, and suggests younger children are unlikely to be the culprits in spreading Covid-19. In a commentary published in the journal Pediatrics, two pediatric infectious disease specialists from the University of Vermont’s Larner College of Medicine looked at studies out of China, Europe, and Australia. They found consistent results: contact tracing usually indicates that it is adults who are passing on the disease — not children.
“Therefore, serious consideration should be paid toward strategies that allow schools to remain open, even during periods of COVID-19 spread,” the researchers concluded. “In doing so, we could minimize the potentially profound adverse social, developmental, and health costs that our children will continue to suffer until an effective treatment or vaccine can be developed and distributed.”
Speaking at Gov. Phil Scott’s press conference on Friday, Dr. William Raszka, one of the commentary’s co-authors, noted that additional evidence had come out since the article’s publication. Several countries in Europe had reopened schools this spring without seeing an uptick in cases. But Raszka also stressed that strict health and safety protocols, and particularly masks, appeared key to keeping infections low.
Dr. Benjamin Lee, the commentary’s co-author, spoke with VTDigger about what is known — and what isn’t known — about the role children play in the pandemic. Lee is an associate professor of pediatrics and pediatric infectious disease specialist at UVM’s Children’s Hospital, and a researcher with UVM’s Translational Global Infectious Diseases Research Center.
Lee stressed that while initial evidence is encouraging, more research is needed to understand the virus in children. New studies are shedding more light; a new large-scale study in South Korea suggests older children could be just as infectious as adults, the New York Times reported on Saturday.
Lee, in a follow-up email, said the South Korea study’s findings are still in line with what prior research has found, and supports recommendations made recently by the National Academies of Science, Engineering, and Medicine that in-person instruction be prioritized for elementary-aged students and those with disabilities.
“The key takeaway for me is that children 0-9 are far less likely to transmit the virus, even in close-contact situations such as within households,” he wrote. However, he added, the new research also “provides a clearer warning about making sure we take good precautions about high school-aged students.”
This interview has been edited for length and clarity.
VTDigger: What do we know about how this disease is spread to and from children?
Benjamin Lee: Unfortunately, part of the challenge is that there’s still a lot that we don’t know about this disease.
Part of the reason for that is that so many of the strategies that were implemented early on, all happened simultaneously. So for example, school closures usually happened at or around the same time as shelter-in-place or stay-at-home orders. And so it can be challenging to disentangle the true impact of any one of those interventions as they relate to children, because most of the social contact that children are going to have during the majority of the year is at school.
What we do know, however, has been painting a pretty consistent picture, and that is that children appear to be less susceptible to getting infected with this coronavirus, and when they do get infected, they tend to have very mild symptoms. Furthermore, it does appear that children — particularly younger children — appear to be far less likely to transmit the virus or pass it along to others.
Most of this evidence comes from household cluster data. So when infections have been identified in children, contact tracing allows us to try to figure out where did the infection come from — did the child get it and then pass it on to the family, or did an adult in the family get it and then pass it along to the children. The pattern that we see is that children are catching this disease from adults in their household, they’re not the ones catching it and passing it along to other children or other adults.
Now, again, how that will change as more school settings reopen is something that we’ll need to keep a close eye on. But so far, the evidence, such as they are, in my mind are enough to suggest that schools can be reopened safely, and that children really are not significant drivers of the pandemic in general.
VTD: So in terms of the body of evidence that we have, it’s not very large yet, but it is consistent?
BL: That would be a fair way to describe it. It’s not a large body of evidence, but consistent across multiple settings, multiple countries. There are a number of countries in Europe, for example, that have now also reopened schools. And that gives us more of a clue specifically on child to child transmission. And by and large in almost every country in Europe, at least, that has opened schools with strategies to mitigate transmission within the school setting, we’ve not seen large school related outbreaks.
There are a couple of exceptions. The most notable exception is probably Israel, where they very rapidly moved to more or less full reopening for all ages, but without implementing much in the way of mitigation, particularly in terms of physical distancing. And so I think the take home message is that for older children — and by older I mean, high school aged children — throwing them back together in a classroom without appropriate mitigation strategies such as cloth facial coverings or physical distancing would be a bad idea.
VTD: What do we know about how children of different ages spread this? What are the thresholds? Can we even get that granular given what we know?
BL: I think that most likely this should be seen as a gradient or a continuum, with the younger children, particularly elementary-aged children, being far less likely to either contract infection or transmit it. As kids get older and start moving into the teenage years, they do start to approach the adult rates in terms of likelihood of acquiring the infection or potentially passing it along.
It would still be important to point out however, that for older kids, as we get into teenage years and approaching 18, even if their likelihood of catching the infection does appear to increase compared to the younger children, they still show similar patterns in that they have very, very low rates of severe disease. And so many of them can catch the infection but generally are even asymptomatic.
VTD: In your commentary in Pediatrics, you talked about how we should prioritize keeping schools open and that we should explore strategies for doing so safely. The available evidence suggests that we can do this responsibly even when there is some level of community spread. Is this any level of community spread? Low levels of community spread?
BL: A lot of the ability to maintain safe school environments has not only to do with things that are happening within the school setting. And going along with that is, you know, if local districts have the resources to implement these plans.
But it also depends so much on the scenario in the community, not only in terms of rates of transmission, but capacity for local healthcare systems to be able to identify cases. To contact trace, isolate, etc. So there are a number of factors that go into it beyond rates of transmission. Therefore, it’s hard to give a hard and fast number in terms of how much is too much or at what point is it safe.
Certainly in Vermont, we are not seeing significant levels of sustained community transmission. So I would argue that Vermont is as well poised as anywhere in the country to sort of model how we can do this and how we can do this safely.
In other areas where transmission is rampant, I do acknowledge that it does become a much harder question. Really the first step in reopening the schools safely is to keep infected people out of the school setting. And if you have lots of community transmission that first primary test becomes much more of a challenge. So therefore, there may be scenarios where local school districts or public health departments may decide right now we just don’t know if we have the sort of ability to absorb this.
I think that would be unfortunate because I think that one can make an argument that if one has the resources and the strategy, that schools probably can develop ways to reopen, even if there’s a significant amount of transmission, but how feasible implementing those approaches are really so dependent on local circumstances.
VTD: I know that there’s been a lot of consternation about the outbreaks linked to child care centers in Texas. Given the evidence that we have, how should people interpret that?
BL: Yes, there has been a lot of attention paid to the Texas daycare scenario. And I will caution that I don’t really have access to a lot of the data that I would like to in order to make a more informed comment on the topic.
I guess what I could say is that in places where there is rampant community transmission, and Texas would qualify, unfortunately, at this point in time, it’s really hard to disentangle, are these infections happening, specifically because transmission is happening within the daycare setting? Or is it just reflecting the fact that there’s a lot of transmission happening in the community?
One of my concerns as daycare centers and schools reopen is that if scenarios like this continue to come up, I think it is going to be very problematic if we start blaming the daycare center or the schools as being the problem, when in fact the problem may be what’s actually happening outside those settings in the greater community at large.
We need to be very careful, particularly, I think, in the media, how these are represented and portrayed, because I think there is a lot of potential for significant misrepresentation of what’s really happening.
My understanding of the Vermont data is that there have been just a handful of isolated cases, either in an adult or in a child who is associated with the daycare either as a staff or provider or an attendee, but in Vermont, throughout this entire time, we have not seen outbreaks associated with daycare centers.
VTD: There was a study that talked about how children, symptomatic children, I believe, had the same viral load as adults, but didn’t seem to be transmitting it as much as adults. What could that potentially tell us?
BL: There has been some interesting data that’s come out, I believe from a research group in Germany, that has demonstrated that infected children, even if they are asymptomatic, even in young children, if you test for the presence of the virus in those children, who are known to be infected, one can detect an amount of virus in the nasopharynx — meaning in the nose — at levels that that can be equivalent to levels that are seen in infected adults. From that they make an inference that children could potentially be seen as being just as infectious as adults.
I think that there are two different aspects to this question. One, can children support significant viral replication, meaning, when a child is infected, can they develop high quantities of virus? And I think the answer to that definitely is yes.
However, that, by itself does not mean that children are just as efficient at getting that virus into another person. So far as the data would suggest that even if children have a high amount of virus in the nose, they may actually be far less efficient at actually transmitting it away from them out of their bodies and into somebody else. And it’s still a bit of a mystery why that would be the case.
So far, in my mind, an explanation that is just as likely as any is that children, particularly younger children, as everyone knows, are just smaller than adults. So when they cough, they may not be able to project infectious viral particles out away from them where they can then get into somebody else, as effectively as adults do.
VTD: But that’s not the case for the flu, right? Kids are just as good about spreading that respiratory disease as adults.
BL: That’s an excellent point. In all honesty, it’s a big mystery why that would be the case that children appear to be so efficient at transmitting the flu but not this virus. Early on in the pandemic, before we really had any data on children and this coronavirus, we basically went to the influenza playbook in terms of how to approach this with children, including the necessity for school closures.
So I would argue that what happened earlier in the spring was a very reasonable approach, thinking that children could be significant drivers of this the way that they are for influenza. I think at this point, we can make the argument that even if we don’t understand exactly why, this virus does appear to act very differently in children than influenza does.
VTD: Do we know anything about whether or not kids are more likely to or less likely to spread this to other children versus less likely to spread this to adults?
BL: I’m not sure we have the definitive data either way, other than to say that it seems likely that they’re less likely to transmit it to anyone, period, compared to adults. Part of it may be that if children are less likely to become infected with it, that child-to-child spread may be less likely because you have the two factors working in our favor. One, the infected child may be less efficient in transmitting it, and two, the other child that they’re in contact with may already be at less likelihood of becoming successfully infected with it.
Particularly for younger children, I think there’s reason to suspect that children really will be inefficient at spreading it amongst themselves, and particularly, again, for younger children. Again, when we get to older kids, so teenagers, high school aged kids, it does seem that that appears to go away to a certain extent.
VTD: What do you think of the theory that the reason children are not often the index case is because they’ve been more cooped up? It’s their parents who were going to the grocery store, their parents were running errands. It’s easier to control the social interactions of children versus adults.
BL: That is an important limitation to the data, and one that we should acknowledge. When we say that we still have very limited evidence, this is one of the challenges. Because children have been, for the most part at home and not around other kids to the same extent that they normally would be, it’s been challenging to generate the evidence, or the studies that see, how does this really affect kids when they’re around lots of other kids, like they would be in the school setting.
That’s why I think it will be so crucial to continue to monitor the situation going forward as schools do reopen. I do think we have a lot of reassuring data from European countries that have reopened schools. That pattern still appears to be holding up. That when children, particularly younger children, are returning to the school setting, that they still appear to be really less likely to catch the disease or to pass it along to their schoolmates.
There have been a number of studies now that have identified cases within the school setting, several from Europe, in France and Ireland, one from Australia. And in those settings, even when we know that there was an infected person in the school, for for the most part, transmission within the school setting, particularly among young children, has been very, very low or non existent.
There’s been one recent study from France that is still in pre-print format. But that has demonstrated that in high schoolers at least, there did appear to be more transmission occurring among the high school students when there was an infected case at the school. But in the elementary school setting, there was virtually no transmission. So the pattern really has been quite consistent in multiple settings.
VTD: What do you still have big questions about when it comes to infectiousness and age?
BL: Probably the most relevant is, are we able to confirm what we have been seeing with more limited evidence up until now? That these patterns will continue to hold true as we reopen schools to a larger degree, so once kids are exposed to a lot more children. So I think that will be a crucial piece of information that we want to keep a close eye on, to make sure that these patterns continue to hold true specifically within the school setting, as more kids go back to school.
I think, why it is that children are so less likely to be affected by the virus? So either that means why they’re so much likely to become infected, and when they do become infected, why they have such a milder course of illness, I think are really important questions to answer.
Going along with that, you know, why is it that they appear to be less likely or less able to transmit it efficiently, whereas the same child who might be infected with influenza, we know, can probably do a pretty good job at passing along the flu. These are really big important questions that hopefully we will begin to have some increased data on as schools reopen more.
I do think it will be really important to try to understand what the pathogenesis, or the biologic basis, for the multisystem inflammatory syndrome associated with Covid-19 truly is.
This is an extremely rare condition. Most kids who do get it, by and large, actually do quite well with proper medical care. But how this happens, or why it happens, I think will be very important questions. For myself, I think it will be very important to try to get a sense of this as it relates to vaccination, because I think that the last thing that we would want to do is to introduce a vaccination strategy, that unknowingly might be setting up children for having that outcome as a longer term complication of vaccination.
VTD: Is there anything else you want to say that I didn’t ask about?
BL: The school reopening issue has become so intensely political in so short a time. Maybe this is just a sign of our times that there isn’t any issue that can escape being politicized, even when it is as important as the health and welfare of our children. I guess my plea would be let’s please not make this a political issue. We need to all work together to make sure that we can reopen school safely regardless of political belief, affiliation or background.
And that relates to another plea that I have and that’s that we really should be doing schools as essential services. I would be surprised if there’s anybody out there who would disagree that educating our children is essential for our society. And especially for the younger children, who really appear to be at the lowest risk of getting infected, and at the lowest risk of transmitting it, a year of either remote learning or less than full-time, in-person education I fear could really have lifelong consequences. Particularly for children on the margins, who may have special healthcare needs, who may have emotional or intellectual challenges to begin with.
I think we really shouldn’t underestimate how profound an impact not providing in-person schooling to these kids really can be. The National Academies of Science recently put out their report on school reopening, and they reached the same conclusion. That really there should be an emphasis on ensuring full time in-person education for K through 5, because it’s so clear that the detrimental effects both on the kids and on the communities.
I’m not trying to diminish in any way how difficult or challenging this is going to be. So I’m not trying to be flippant in any way when I say that the schools should reopen. We understand that it’s going to be a monumental challenge. But I would argue that if we view this as an essential service that this is a challenge that we will be able to rise up to face. We just have to make the decision that it is one that we’re going to take on.
After VTDigger spoke with Lee, a study was published about children in South Korea. He shared his reactions to the research by email. This has been edited for length and clarity:
I don’t know that the findings actually change much. In fact, they confirm much of what we had suspected all along. I always pay close attention to the South Korean data, because they have had one of the best mechanisms in the world for testing and contact tracing. The numbers that they are reporting are definitely on a much larger scale than many previous reports.
The key takeaway for me is that children 0-9 are far less likely to transmit the virus, even in close-contact situations such as within households. This provides further evidence that school reopening for elementary school students can be done safely and the goal should be full-time in person education, as the National Academy of Sciences recently recommended. […]
The one area where it may have an impact is that it provides a clearer warning about making sure we take good precautions about high school-aged students. There are a couple of aspects of the Korean data that are unclear. They report that 10-19 year-olds had the highest levels of within-household transmission than other age groups, suggesting they are efficient spreaders of the virus, but their rates of transmission among non-household contacts was actually the same as for younger children. It is not clear to me WHO they were spreading to within their households, as those data weren’t provided. For example, is this being driven by teenagers taking over child care duties once schools were closed, and they were transmitting to their younger siblings, but not their parents?
It would have been nice to see more granularity in the age breakdowns for the children as well. I would suspect that the rates of transmission were highest for the 18-19 year olds and lower for the 10-12 year olds, as biologically I still think there are important differences between these age groups but they are all lumped together for this analysis (as is typically done by necessity for many of these epidemiological studies).
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