People are blaming 'immune debt' for a 'triple epidemic' of RSV, flu and COVID hitting children across the country.  But experts say it's misguided at best, and could even be harmful.

People are blaming ‘immune debt’ for a ‘triple epidemic’ of RSV, flu and COVID hitting children across the country. But experts say it’s misguided at best, and could even be harmful.

This fall, North American children are not doing well.

Children’s hospitals are overflowing with an unusually high number of patients with several different viruses, mainly RSV, fluand covid, but also flu-like viruses such as rhinoviruses and enteroviruses. Many are at or near capacity, and some are well beyond, having made room for the overflow of patients in offices, gift shopsplay areas and car park tents.

Parents, pediatricians and public health officials are asking the same question: how did we get here?

A popular idea that has emerged in the public health community: the surge is due to “immunity debt,” a newly coined term. According to the theory, children have been exposed to fewer germs — COVID and otherwise — over the past three years due to pandemic precautions like masking and social distancing, and their immune systems have atrophied. Now that society has reopened, children face the usual Petri dish of viruses with weakened defenses, causing an onslaught of disease – and possibly greater and more severe levels of disease than would otherwise have occurred. .

But the experts Fortune spoke with saying the theory is unscientific at best and destructive at worst, disagreeing with any argument that COVID precautions damaged the immune system, and emphasizing a wide range of factors driving the “triple current epidemic.

What is Immunity Debt?

When it comes to why children are being hit so hard by viruses this fall, immune debt is “certainly the most popular hypothesis floating around,” said Dr. Lael Yonker, assistant professor of pediatrics at Harvard Medical. System at Massachusetts General Hospital. Fortune.

The general idea is that children born during the pandemic were protected from the viruses they would normally have been exposed to if they had interacted with more people – and that this weakened their defences.

“These kids are now a year old, two years old, and they’ve never seen RSV,” she said. “They haven’t built up immunity in general, and now they’re getting really sick.”

The immune debt theory was first proposed by French scientists in a 2021 opinion piece in Infectious Diseases Now. Pandemic precautions such as masking and social distancing have kept hospital systems from being overwhelmed in the short term, flattening the so-called COVID curve and dramatically reducing the spread of other pathogens. But they increased the likelihood of future outbreaks, the authors wrote, “due to an increasing proportion of ‘susceptible’ people and declining herd immunity in the population.”

Since the article was published, discussion of the concept has exploded, spilling over from medical journals to Twitter and media outlets.

But some say the debate has shifted from a scientific discussion to a political one, with opponents of the cover-up using the theory to try to prove the cover-up caused harm.

Dr Amesh Adalja, an infectious disease specialist and senior fellow at the Johns Hopkins Center for Health Security, thinks the term is “misused and misinterpreted” and “creates unnecessary political fights on social media”.

“I don’t necessarily like that ‘immunity debt’ becomes a made-up phrase,” said Dr. Sarah Combs, an emergency physician at Children’s National Hospital in Washington, DC. Fortune.

“We know there’s been a lot of politicization during the pandemic, and I’ve seen some people pick up [the term] and say: ‘Ha ha! It proves that we were doing all the wrong things, that masking was wrong, and that we should never do it again.

“I’m going to come out and say that’s absolutely wrong. Using that as rhetoric that says, “Clearly no public health measures were necessary,” doesn’t work. It’s damaging. »

Dr. Jason Catanzaro, a pediatric allergist and immunologist at National Jewish Health in Denver, points out that masking was much less common in some parts of the country — and yet children in those states are struggling just as much right now during the triple outbreak.

“As far as I know, there’s not a big part of the country – red or blue – that’s spared from RSV,” he said.

“Our immune system was working very well”

Several experts who Fortune spoke with saying that “immunity debt” is not the reason pediatric wards are inundated with patients this year.

It’s not really a scientific term, says Dr. John Bradley, medical director of infectious diseases at Rady Children’s Hospital in San Diego and a distinguished professor at UC San Diego School of Medicine. Fortune. And children’s immune systems haven’t stopped working during the pandemic, says Catanzaro.

“They were still monitoring cells for cancer, interacting with trillions of microbiota on an ongoing basis to sort out which bacteria were good and bad,” he said. “Our immune system was working very well.”

Instead, Bradley and Catanzaro believe the surge is, in large part, due to a massive cohort of children with healthy immune systems all reentering society around the same time. Their immune systems weren’t weakened, but they may not have had their usual annual vaccinations, or their immunity “boosted” by exposures to non-vaccine viruses like RSV, they say.

Catanzaro likens the American pediatric population to a young child who enters daycare for the first time and spends the next few months catching what seems like every disease under the sun.

“Would that be considered an immunity debt?” He asked. He described how his daughter went through the common script when transitioning into pre-pandemic child care. “I don’t think his immune system was weak. She had simply never seen these things before.

Many potential factors and even more questions

Experts say there could be a myriad of factors behind children’s ‘triple epidemic’ – and most of them are non-virological.

Hospitals are understaffed and there are relatively few pediatric hospital beds in the United States. Immunization rates for children have also declined over the in recent years, leading to more infections. And it could also be a worse than average flu year. The same may be true for the RSV, which may have evolved to be more powerful than it once was.

But some experts like Catanzaro and Yonker say others could be in play this fall. Many North American children returned to in-person learning in the past year, largely unmasked, and the continent has not seen the same wave of hospitalizations as it does today.

“A ton of people have been diagnosed with RSV in the middle of the pandemic, and there have been no mass hospitalizations,” Catanzaro said.

“We weren’t closing ICUs and filling hospitals,” Yonker added.

Both say it’s possible that COVID – which has infected the majority of the world’s population – has taken a toll on the immune systems of those who have already been infected, much like measles can. COVID can alter the production of interferon, a substance produced by the body that helps the immune system fight infections and diseases like cancer, according to Catanzaro.

So far, there is no evidence to prove this theory. But measles in unvaccinated children can “lead to immune amnesia,” Catanzaro said, citing a 2015 article in Science who “demonstrated that measles annihilates pre-existing immunity to earlier viruses”.

Bradley expects viruses like influenza and RSV to return to their regular seasonal patterns within a few years. And he expects COVID to eventually follow suit.

Yet the question of what caused the tripledemic is – and will remain – more than an academic exercise for the millions affected this winter.

“There are a lot of people whose kids are on oxygen with RSV who would like an answer,” Catanzaro said.

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