Scientists discover possible reason kids better at battling COVID-19

INDIANAPOLIS (WISH) — The U.S. surpassed 200,000 coronavirus deaths on Tuesday yet children 18 and younger account for just one-third of 1% of this group. 

So, why is their infection so much less severe compared to adults? Doctors were wondering why, but now there may be an answer.

News 8 spoke with Dr. Kevan Herold, a professor and immunobiologist at Yale University, about his recent discovery. 

Gillis: We’re talking about how COVID-19 affects children less than adults and how it could be related to two specific molecules they exhibit in their lungs. What are these molecules? And it’s interesting because why would children have more than adults when their immune system isn’t fully developed?

Herold: The reason we started this research is because most of what’s been published on COVID-19 has focused on adults and many times adults do poorly. But it has been recognized since the very beginning that kids tended to do very well. So the question was why do kids do so well?

Some people have postulated that it’s because they don’t get infected. But the other hypothesis is maybe they have an immune response that is better able to contain the virus in some way. And to our surprise what we found was that two cytokines–which are products of immune cells–called IL-17A and INF-g were actually at higher levels in children compared to adults. 

Now there are a variety of other cytokines that are measured and for those who had more severe disease we found–just as others have–that those were elevated. But the surprise here is that these two cytokines were actually higher in the kids compared to older individuals. 

Gillis: And…why?

Herold: The “why” of course is the important question. One of the findings from our paper was that when we looked at the cells that most people think make these products, called T-lymphocytes and are types of immune cells, we didn’t find they were made in response to the virus. And what we’ve postulated is that it’s cells within the lung that are able to make these products. 

Our data is basically saying: “We don’t see them in the peripheral blood” so the speculation must be that they are in the lungs. And we’re wondering if that may set up a protective response in the children. So, the big question, of course, is: Is there a way to stimulate that response early on and could result in a more benign course with COVID-19?

Gillis: Might these two molecules play a larger role than antibodies?

Herold: That’s an interesting question because there were differences in the antibody responses in children compared to adults and our data suggests that the adults had a more robust antibody response, which is somewhat counterintuitive. But then there are the multi-system inflammatory syndrome patients. And these children present after they’ve been exposed or had COVID-19. They all had antibodies against COVID-19–at least the patients that we studied. But they didn’t have the same lung disease that children who initially presented the infection and were hospitalized with the coronavirus. So, what exactly is going on in those patients I think still needs to be evaluated further. But they also had higher levels of the molecules IL-17A and INF-g. So, whether that represents a successful protective response or perhaps one that is comes afterwards and is too late…we’re not sure. 

Gillis: These molecules decline with age? Do we know the rate of decline?

Herold: We don’t know the rate. But when we looked older individuals when they present…the levels really are very mild. And it’s really only those younger than age 22 where we saw the increased levels. 

Gillis:  Could this be like convalescent plasma where we take these molecules and then we can inject them into a COVID-19 infected patient? Is that a possibility?

Herold: One of the limitations of the study is we don’t know whether these molecules we’ve identified are markers or the cause of the better immune response in children and that’s a really important question that needs to be answered. It could be that what it’s doing is telling us about cells in the lungs that may be able to mount a good immune response against COVID-19 rather than the direct cause of the good immune response. 

So, I don’t think anyone would advocate giving these molecules directly, but it may be possible–someway or another–to activate that immune response early on, perhaps in an older individual, which may help them better cope with the virus.

Gillis: Would you share with us your future research?

Herold: We’re very interested in further exploring these cells and if there are other cells that might be very active in children and are not as active in adults that may be responsible for successful containment of the coronavirus. One of the problems is it’s not easy to get a hold of lung tissue and so we’re trying to figure out other ways to get cells that may provide us some clues as to which cells are responsible for containing the virus. 

News 8’s medical reporter, Dr. Mary Elizabeth Gillis, D.Ed., is a classically trained medical physiologist and biobehavioral research scientist. She has been a health, medical and science reporter for over 5 years. Her work has been featured in national media outlets. You can follow her on Instagram @reportergillis and Facebook @DrMaryGillis.