Kids are back in school. The federal government seems to be on the verge of approving vaccines for younger children. And as more adults are fully vaccinated, much of the US is slowly returning to normal.
But there remains a lingering question, particularly for parents of young children: What is the risk of Covid-19 to kids, especially after the rise of the delta variant?
There were reports this summer of more children under 18 falling ill with Covid-19, and some pediatric hospital wards filling up, leading many to believe that the pandemic is now a serious threat to children, too. At the very least, it’s abundantly clear now that children can be infected by and transmit the coronavirus.
But experts maintain that the risks most children face from Covid-19 are low, even with the delta variant. “The risk in children has not changed with the new variant as far as we can tell,” Betsy Herold, a pediatric infectious disease physician at the Albert Einstein College of Medicine, told me.
Herold estimates that less than 2 percent of children known to be infected by the coronavirus are hospitalized, and less than 0.03 percent of those infected die. It’s difficult to draw direct comparisons to American adults now that two-thirds in the US are vaccinated, while most kids aren’t. But before widespread vaccination, about 10 percent of people infected with Covid-19 were hospitalized, and around 1 percent died.
While there isn’t as much research on children and Covid-19 as experts would prefer, the data we do have suggests the risk of longer-term consequences, like long Covid or MIS-C (in which several organs become inflamed), is also very low.
The delta variant is both more transmissible and more widespread than earlier variants, which has meant that even a low-risk disease has filled up many pediatric wards. But while delta has made more children sick, it has not made infected children sicker — it doesn’t appear to be linked to worse disease among kids, experts said.
That’s still a public health problem. If the risk of death for children is around 0.01 percent and 1,000 children are infected, you would expect no deaths. But if 1 million are infected, you would expect 100 deaths. Increased transmission, not a deadlier virus, helps explain why pediatric wards are more crowded now than they were earlier in the pandemic, and shows that even a low-risk disease could lead to many deaths if enough children catch it. With nearly 5 million children with confirmed infections in the US so far, we are seeing that in the real world.
We also don’t know exactly why children are at much lower risk of Covid-19, and the situation could still change — a variant could evolve that proves more dangerous to children.
But experts, on the whole, are optimistic so far that children’s natural defenses against the virus have held up. That resilience isn’t just good news for parents; it’s a hopeful sign for the future of Covid-19. As the virus becomes endemic, future generations might be regularly exposed to SARS-CoV-2 at a young age. But children’s natural defenses are likely to crush it, building immunity, piece by piece, that could help shield them for a long time. Coupled with the vaccines, the generational buildup in natural immunity could, over time, defang the virus.
Kids are still at relatively low risk of severe Covid-19
Compared to other age groups, people under 18 are at much lower risk of serious illness and death from Covid-19. The death rate for Americans under 18 who are infected is about 0.01 percent, compared to 5 percent for 65- to 74-year-olds, 12 percent for 75- to 84-year-olds, and 25 percent for people 85 and older. In total, people 50 and up make up 94 percent of Covid-19 deaths in the US, based on federal data.
“We’ve known from the beginning that Covid is relatively mild in children compared to adults — and especially older adults,” Shamez Ladhani, a pediatric infectious diseases specialist at St. George’s Hospital in London, told me.
The risk is even lower for children under 10, experts told me. Infants under 1 year old might be at higher risk than slightly older children due to their immature immune systems, but the data is way too thin to draw any conclusions for infants.
Another way to gauge risk is to compare Covid-19 to other significant causes of death. Covid-19 has killed 280 children under 18 from January through September 2021, the time span in which the alpha and delta variants were active. Flu and pneumonia, heart disease, drowning, guns, and motor vehicles were all deadlier to children during the same time periods annually from 2015 to 2019 (the latest years with available data).
As one example: The number of children under 18 who died in vehicle crashes from January through September in recent years was nearly six times higher than the number of children who died of Covid-19 from January through September of this year.
These numbers can help contextualize risk. “One of the best ways to communicate risk — and for me, personally, to even think about risk — is to compare the risk of something I don’t understand to the risk of something I do,” Stephen Kissler, an infectious disease researcher at Harvard, told me.
Covid-19 deaths are likely lower than they would be if people had not engaged in social distancing and other precautions, meaning they could increase as the country shifts back to a pre-pandemic normal. But many parts of the country already have undergone that shift with only a relatively small increase in Covid-19 deaths among children, with surges concentrated among older adults, even as the delta variant spread.
What about other risks of Covid-19 among children?
One concern is multisystem inflammatory syndrome in children, or MIS-C, which appears in some children after a Covid-19 infection. But the risk of MIS-C is also very low: Around 4,700 MIS-C cases and 41 deaths were confirmed in the US as of August 27, 2021, according to the Centers for Disease Control and Prevention. At that point, there were 3.7 million total Covid-19 cases among children 17 and under in the US.
Long Covid is also a concern. A huge problem is that the research on long Covid in kids is very thin — so thin that some experts didn’t feel comfortable talking about the issue much, if at all.
Still, the research we do have, experts said, suggests long Covid is not a big threat to kids. Looking at a sample of 1,700 children ages 5 to 17 in the UK, a study in The Lancet Child & Adolescent Health found that less than 2 percent experienced symptoms for at least eight weeks, and symptom severity appeared to decrease over time.
One possible explanation: Long Covid seems to happen more often after severe illness, which is less common for children. A study analyzing private health care claims, by the nonprofit FAIR Health, found hospitalized Covid-19 patients were almost twice as likely to develop “post-Covid conditions” as patients who were symptomatic but not hospitalized.
Finally, there’s the risk children’s transmission may pose to others. “If kids continue to get infected, others will continue to get infected who are unvaccinated — and the virus will continue to mutate,” Jen Kates, director of global health and HIV policy at the Kaiser Family Foundation, told me. “It’s not just that we need to protect the kids. It’s this larger question.”
Children do appear to transmit the coronavirus less than adults do, Ladhani said. One possible explanation: Kids are less likely to develop symptoms than older groups, and have those symptoms for shorter periods. And the coronavirus is less likely to spread if it’s not being coughed or sneezed out into the world.
Children’s defenses against Covid-19 have held up, even against delta
The coronavirus, thankfully, remains a small threat to children overall. What’s less clear is why kids haven’t been hit harder by Covid-19.
The explanations so far are largely speculative.
One possibility is children’s immune systems are better built to deal with novel viruses. After all, to young immune systems, most viruses are novel. Outside of some defenses passed down by parents and the protection from childhood vaccines, kids adapt to the pathogens around them through repeated exposure. So when a new coronavirus began to spread, the theory goes, children were better able to deal with the threat. But for adults, especially older ones, encountering a new pathogen is rarer, and so their immune systems perhaps haven’t been able to deal with a novel threat to the same degree as their younger counterparts.
Two studies, by Herold, point in that direction, finding that the adaptive part of the immune system appears to be more active in adults than children. Herold suggested that’s because kids’ “innate response is better at dealing with Covid and perhaps other novel pathogens in general.” (For more on this research, I recommend Smriti Mallapaty’s recent article in Nature.)
Another possibility is that children, generally, have fewer health problems that put them at risk of severe illness from Covid-19. A range of comorbidities are known to make the virus a much bigger threat, including asthma, obesity, cancer, and heart disease. Some of these are more or as likely during childhood, but many, like cancer and heart disease, are more likely to happen with older age. As a result, kids “will cope better when they are infected,” Ladhani said.
There are other theories, from social and biological differences in coronavirus exposure to potential side effects of non-Covid vaccines. But, again, this field of research is just starting, and no one has a sure explanation — the ultimate contributor could be something we don’t even know about yet.
Given the uncertainty, experts also can’t say that kids’ protection against Covid-19 will hold true forever. It’s possible a future variant will end up more dangerous for children, even if that hasn’t been the case with delta. It’s yet another reason to mitigate the spread of the virus as much as possible: to deny it more chances to replicate and mutate into something that children’s defenses might not so easily conquer.
Different people will have different risk tolerances
The data isn’t going to lead every parent to the same conclusions. Some people want to wait to return to normal until Covid-19 cases decline, after the current wave of delta fully eases (as is already starting to happen), or until everyone can get vaccinated, including kids. Others see higher vaccination rates in their community or nationwide as a prerequisite to easing up on precautions. Many are already moving on, at least to some degree, ready to put the virus and its impacts on day-to-day life behind.
Among the experts I’ve spoken to over the past several months, there are still divisions on when the time is right to ease up. “These are really hard, personal decisions,” Crystal Watson, a senior scholar at the Johns Hopkins Center for Health Security, told me. “There’s not a one-size-fits-all.”
There have been some points of agreement. For one, some places with lots of children, particularly schools, should do what they can to stop transmission, such as widespread testing, masking, and better ventilation. As soon as a vaccine is available, children should get the shots for an extra layer of protection, not just for themselves but also to prevent wider coronavirus spread and to block new variants.
At the same time, experts also widely agree the general risk of Covid-19 illness will likely never be zero again. The virus will be weakened over time through natural immunity and vaccination, but it will become endemic — continuing to spread in some form, perhaps in new variants, and potentially causing waves of severe illness and death on occasion. That suggests people will have to tolerate some level of risk going forward. And at least for kids, Covid-19 already isn’t too far from the risks people widely accepted before the pandemic.
Kids’ resilience against Covid-19 offers a way out of the pandemic
As the world transitions from the pandemic to endemic stage of this coronavirus, children’s natural defenses against Covid-19 could prove crucial — providing a relatively safe route to much higher levels of natural immunity across the population.
“Over time, as SARS-CoV-2 becomes an endemic virus, basically everybody is going to get exposed to it multiple times by the time they turn 5 or 10,” Kissler, the infectious disease researcher, said. The repeated exposure — and build-up of immunity it produces — could turn the virus into something more like the common cold or seasonal flu than the pathogen that’s warped our lives since the spring of 2020.
Obviously, the continued spread among children would be a big problem if kids generally got very sick with Covid-19. Since that’s not the case, the process can play out with few risks to kids themselves — especially if it’s bolstered by childhood vaccines.
There are some lingering questions: How durable is natural and vaccine-induced immunity to Covid-19? What will be the earliest age at which someone can get vaccinated? Will a new variant overcome the effectiveness of the population’s immunity that’s been built up? The answers could shape, or completely alter, how the transition to endemic Covid-19 plays out.
But other viruses have followed this path. Earlier strains of the flu that killed up to millions of people worldwide are still present in some form today. But as humans have over time been repeatedly exposed to these viruses, they’ve built population-level immunity to what once was a more vicious threat. And a deadly pandemic in 1889, originally believed to be caused by the flu, may have actually been caused by a coronavirus that is still with us as one of the many pathogens causing a common cold.
Coupled with vaccines and potential medical breakthroughs in treatment, Covid-19 could follow a similar trajectory. The wonder of vaccines is they can speed up this process, giving people the immunity that they once had to earn through a serious — and at times deadly — bout of sickness.
In short: The world has been fortunate, throughout the pandemic, that kids aren’t hit hard by Covid-19. But that luck also may extend to the pandemic’s aftermath — to ensure we can move past the coronavirus once and for all.