COVID-19: Experts Explain Children’s Immune System Against the Virus

Many hospitals have reached a sad new low eighteen months into the COVID-19 epidemic, with the Delta variant driving a huge comeback of illness. The coronavirus is now causing them to lose infants.

The first COVID-related newborn fatality was recorded in Orange County, Florida, and another baby died in Mississippi. In late August, a kid under the age of one died in Merced County, California.

Until the delta version lay siege this summer, almost all youngsters seemed to be immune to COVID-19’s harshest effects, for reasons experts couldn’t explain.

Although there is no proof that the delta variant causes more severe illness, the virus is so contagious that children are being sent to hospitals in huge numbers, mainly in low vaccination rates. According to the American Academy of Pediatrics, almost 30% of COVID-19 infections recorded in the week ending September 9 were in children.

In the same week, doctors identified more than 243,000 cases in children, bringing the total number of COVID-19 infections in children under the age of 18 to 5.3 million, with at least 534 fatalities since the outbreak began.

It’s a matter of simple math, according to experts.

However, the current outbreak brings fresh urgency to a topic that has perplexed experts throughout the pandemic: what prevents most youngsters from getting severely ill? And why does that safeguard sometimes fail?

TOPSHOT – A girl in a wheelchair (C) hospitalized in the Department of paediatric rehabilitation and developmental disabilities of IRCCS at the San Raffaele hospital in Rome, interacts with her visiting mother through a plastic protection to avoid catching the COVID-19 on December 22, 2020. – The San Raffaele in Rome has decided to let children in hospital to give their relatives a hug, by equipping themselves with a plastic tent that allows them to meet and hug without running the risk of infection. (Photo by Filippo MONTEFORTE / AFP) (Photo by FILIPPO MONTEFORTE/AFP via Getty Images)

ALSO READ: Children Infected With COVID-19 Continues To Spike Due To Delta Variant, CDC Says

COVID-19 Child Immune System Explained

Doctors couldn’t explain why children’s immune systems were so much better at fighting the coronavirus for most of the epidemic.

Despite the recent spike in the number of children admitted to hospitals, young people are far less likely to become severely sick. 

According to the American Academy of Pediatrics, less than 1% of children diagnosed with COVID-19 are hospitalized. Around 0.01 percent die – numbers that haven’t altered in recent months. The majority of youngsters brush off the illness with a sneeze.

Dr. Lael Yonker, an associate professor of pediatrics at Massachusetts General Hospital, said a growing body of data indicates that kids’ innate immune systems typically nip the infection early on. Hence, the systems prevent the virus from establishing a foothold and replicating uncontrolled.

Drs. Betsy and Kevan Herold, a husband-and-wife team, discovered that children have a powerful mucosal immunity. That is 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 frequently come into contact with germs.

These membranes function similarly to the stacked stone walls that kept attackers out of medieval towns. They’re made up of epithelial cells, coat numerous internal organs, and sit alongside dendritic cells and macrophages, two necessary immune-system troops. This was according to Betsy Herold, head of the division of pediatric infectious diseases at Albert Einstein College of Medicine.

These cells are coated with proteins known as pattern recognition receptors, which serve as sentinels, constantly monitoring the landscape for anything out of the ordinary. When the sentinels detect anything foreign, such as a new virus, they signal cells to release proteins called interferons, which help the body’s immune response coordinate.

Roland Eils and colleagues from Germany’s Berlin Institute of Health discovered that children’s upper airways are “pre-activated” to combat the new coronavirus in a research published in Nature Biotechnology in August. These sentinels abound in their lungs, including ones that excel in detecting the coronavirus.

This enables children to engage their innate immune system right away, producing interferons that help kill down the virus before it can take root, according to Eils.

On the other hand, adults have much fewer sentinels on the alert and react to the virus in approximately two days, according to Eils. The infection may have multiplied by that point, making the fight much more difficult.

When the body’s innate immunity fails to contain a virus, it may turn to the adaptive immune system, a second line of defense that adjusts to each danger. For example, the adaptive immune system creates antibodies and customizes every virus or bacteria that the body meets.

Antibodies are one of the simplest components of the immune response to quantify and therefore are often used as proxies for protection. Hence, Betsy Herold says that children don’t appear to require as many to fight COVID-19. 

Children with COVID-19 had less neutralizing antibodies than adults, according to Herolds’ study. Meaning, both children and adults typically produce enough antibodies to prevent recurrent coronavirus infections after natural infection or vaccine.

While the adaptive immune system may be beneficial, it can also be harmful at times.

Dr. Jeremy Luban, a professor at the University of Massachusetts Medical School, said healthy children have significant numbers of innate lymphoid cells. Lymphoids are a kind of peacekeeper cell that helps quiet a hyperactive immune system and repair lung damage.

Children are born with many of these cells. But as they become older, their number decreases. COVID-19 patients, both children and adults, have less of these repair cells, according to Luban.

Men also have fewer repair cells than women, which may explain why men are more likely than women to die from COVID-19.

Both toddlers and adults may acquire “long COVID,” which affects around 10% of younger people and up to 22% of those aged 70 and above. Around 4 to 11 percent of children experience chronic symptoms, according to experts.

RELATED ARTICLE: COVID-19 Vaccine: Parents Plead Experts To Vaccinate Kids 12 Below