Studies with more samples on vaccine reaction in children are missing 0:54
(CNN) -
Eighteen months after the start of the covid-19 pandemic, with the delta variant fueling a massive resurgence of disease, many hospitals are reaching a new heartbreaking low.
Now they are losing babies to the coronavirus.
The first reported covid-related newborn death occurred in Orange County, Florida, and a baby died in Mississippi.
Merced County in California lost a child under the age of one in late August.
"It's so hard to watch children suffer," said Dr. Paul Offit, an infectious disease expert at Children's Hospital of Philadelphia, who, like other pediatric hospitals across the country, has been inundated with covid patients.
Until the delta variant besieged this summer, almost all children seemed to be spared the worst ravages of COVID-19, for reasons scientists didn't fully understand.
Although there is no evidence that the delta variant causes more serious disease, the virus is so infectious that children are being hospitalized in large numbers, mainly in states with low vaccination rates.
advertising
Nearly 30% of COVID infections reported during the week ending September 9 were in children, according to the American Academy of Pediatrics.
Doctors diagnosed more than 243,000 cases in children in the same week, bringing the total number of covid infections in children under 18 years old since the start of the pandemic to 5.3 million, with at least 534 deaths.
Cuban children are the youngest in the world to be vaccinated against covid-19
Experts say it is a matter of basic math.
"If 10 times more children are infected with delta than previous variants, then of course we will see 10 times more children hospitalized," said Dr. Dimitri Christakis, director of the Children's Center for Health, Behavior and Development at the Institute of Seattle Children's Research.
But the most recent increase gives new urgency to a question that has puzzled scientists throughout the pandemic: What protects most children from becoming seriously ill?
And why does that protection sometimes fail?
"This is an urgent and complex question," said Dr. Bill Kapogiannis, senior physician and infectious disease expert at the Eunice Kennedy Shriver National Institute of Child Health and Human Development.
"We are doing everything we can to address it, using all the tools that we have available," Kapogiannis said.
"The answers cannot come soon enough."
Investigating the immune systems
Vaccinated youth and children would help herd immunity 0:43
For much of the pandemic, doctors could only wonder why children's immune systems were so much more successful in rejecting the coronavirus.
Despite the alarming number of children hospitalized in the recent increase, young people are much less likely to become seriously ill.
Less than 1% of children diagnosed with covid are hospitalized and about 0.01% die, rates that have not changed in recent months, according to the American Academy of Pediatrics.
Most children ignore the virus with little more than a snort.
A growing body of evidence suggests that children's innate immune systems generally cut off the infection early on, preventing the virus from establishing and multiplying uncontrollably, said Dr. Lael Yonker, assistant professor of pediatrics at the General Hospital of Massachusetts.
In a series of studies published last year, the husband and wife team of Drs.
Betsy and Kevan Herold found that children have particularly strong mucous immunity.
It is so named because the key players in this system are not in the blood, but in the mucous membranes that line the nose, throat, and other parts of the body that are frequently found with germs.
These membranes act as the layered stone walls that protected medieval cities from invaders.
They are made of epithelial cells, which also line many internal organs, which lie alongside key immune system soldiers called dendritic cells and macrophages, said Betsy Herold, chief of the division of pediatric infectious diseases at the Albert Einstein College of Medicine.
Sentinels of the immune system
Significantly, these cells are covered in proteins, called pattern recognition receptors, that act like sentinels, continually scanning the landscape for something unusual.
When sentinels notice something strange, like a new virus, they alert cells to start releasing proteins called interferons, which help coordinate the body's immune response.
In an August study in Nature Biotechnology, Roland Eils and colleagues at Germany's Berlin Institute of Health found that children's upper airways are "pre-activated" to fight the new coronavirus.
Their airways are teeming with these sentinels, including some who excel at recognizing the coronavirus.
That allows children to immediately activate their innate immune systems, releasing interferons that help turn off the virus before it can establish itself, Eils said.
By comparison, adults have far fewer sentinels lurking and take about two days to respond to the virus, Eils said.
At that point, the virus may have multiplied exponentially and the battle becomes much more difficult.
Countries that are vaccinating children against covid-19
When innate immunity fails to control a virus, the body can turn to the adaptive immune system, a second line of defense that adapts to each unique threat.
The adaptive system creates antibodies, for example, adapted to each virus or bacteria that the body encounters.
While antibodies are some of the easiest pieces of the immune response to measure and are therefore often cited as surrogates for protection, children don't seem to need as many to fight COVID, Betsy Herold said.
In fact, Herold's research shows that children with covid have fewer neutralizing antibodies than adults.
(Both children and adults usually produce enough antibodies to thwart future coronavirus infections after a natural infection or a vaccine.)
While the adaptive immune system can be effective, it can sometimes do more harm than good.
Like soldiers who kill their comrades with friendly fire, an overactive immune system can cause collateral damage, unleashing an inflammatory cascade that tramples not just viruses, but healthy cells throughout the body.
This is how children's immune systems react
In some covid patients, uncontrolled inflammation can lead to life-threatening blood clots and acute respiratory distress syndrome, which occurs when fluid builds up in the lung alveoli and makes breathing difficult, Betsy Herold said.
Both are common causes of death in adult covid patients.
Because children generally clear the coronavirus very quickly, they avoid this type of dangerous inflammation, he said.
Research shows that healthy children have large amounts of a type of pacifying cell, called innate lymphoid cells, that help calm an overactive immune system and repair damage to the lungs, said Dr. Jeremy Luban, a professor in the College of University of Massachusetts Medicine.
Children are born with many of these cells, but their number decreases with age.
And both children and adults who are sick with covid tend to have fewer of these repair cells, Luban said.
Men also have fewer repair cells than women, which could help explain why men are at higher risk of dying from COVID than women.
Both children and adults can develop "long-term covid," the persistent health problems experienced by about 10% of younger adults and up to 22% of those over 70 years of age.
While only 4% to 11% of children have persistent symptoms.
Questions without answer
Vaccinated youth and children would help herd immunity 0:43
Scientists have fewer clues about what goes wrong in certain children with covid, said Kevan Herold, who teaches immunobiology at Yale School of Medicine.
Research suggests that children have stronger innate immune systems than adults because they have experienced many recent respiratory infections during the first few years that can prime their immune systems for later attacks.
But not all children ignore COVID so easily, Eils said.
Newborns have not lived long enough to prepare their immune systems for battle.
Even young children may not get a strong answer, he said.
At Children's Hospital New Orleans, half of the covid patients are under the age of 4, said Dr. Mark Kline, infectious disease specialist and chief physician.
"We have had babies as young as 7 weeks, 9 weeks old in the ICU on ventilators," Kline said.
"We had a 3-month-old baby who required ECMO," or extracorporeal membrane oxygenation, in which the patient is connected to a machine similar to the heart-lung bypass machine used in open heart surgery.
This is how hospitals decide who to give a bed to when they are saturated
Even previously healthy children sometimes die from respiratory infections, from covid to influenza to respiratory syncytial virus.
But studies have found that 30% to 70% of children hospitalized with Covid had underlying conditions that increase their risk, such as Down syndrome, obesity, lung disease, diabetes, or immunodeficiencies.
Premature babies are also at higher risk, as are children who have undergone cancer treatment.
One thing hospitalized children have in common is that almost none are vaccinated, said Dr. Mary Taylor, president of pediatrics at the University of Mississippi Medical Center.
"There really is no way of knowing which child with covid will have a cold and will be fine and which child will be seriously ill," Taylor said.
"It is a feeling of helplessness for families to feel that there is nothing they can do for their child."
Although scientists have identified genetic mutations associated with severe covid, these variants are extremely rare.
The role of "autoantibodies"
Scientists have been more successful in clarifying why certain adults succumb to COVID-19.
Some cases of severe covid in adults, for example, have been linked to the wrong antibodies that target interferons, rather than the coronavirus.
An August study in Science Immunology reported that such "autoantibodies" contribute to 20% of COVID deaths.
This is the most effective vaccine against covid-19 in the US 0:43
However, autoantibodies are very rare in children and young adults, and they are unlikely to explain why some young people succumb to the disease, said study co-author Dr. Isabelle Meyts, a pediatric immunologist at the Catholic University of Leuven in Belgium.
Although hospitalizations are declining across the country, only now are some of the most serious consequences of the infection emerging.
What is multisystem inflammatory syndrome or MIS-C?
Two months after the delta surge, hospitals across the South are seeing a second wave of children with a rare but life-threatening condition called multisystem inflammatory syndrome, or MIS-C.
Unlike children who develop covid pneumonia, the leading cause of hospitalizations among children, those with MIS-C usually have mild or asymptomatic infections, but become very ill about a month later and develop symptoms such as nausea, vomiting, rash. , fever and diarrhea.
Respirator use increases 129% in Miami-Dade 0:54
Some develop blood clots and dangerously low blood pressure.
More than 4,661 children have been diagnosed with MIS-C and 41 have died, according to the Centers for Disease Control and Prevention.
Although scientists do not yet know the exact cause of MIS-C, research by Yonker of the Massachusetts General Hospital and others suggests that viral particles can leak from the intestine into the bloodstream, causing a system reaction throughout the body.
It is too early to know if children who survive MIS-C will suffer lasting health problems, said Dr. Leigh Howard, a pediatric infectious disease specialist at Vanderbilt University Medical Center.
Although an August study in The Lancet shows that the delta swing doubles the risk of hospitalization in adults, scientists don't know if that's true for children, said Dr. Anthony Fauci, the nation's top infectious diseases official.
"Certainly, at this time, we don't know if children have a more serious illness, but we are watching it," he said.
To protect children, Fauci urged parents to vaccinate themselves and children 12 and older.
As for children too young for covid vaccines, "the best way to keep them safe is to surround them with vaccinated people."
This story was produced by KHN.
Covid-19 vaccines
