LONDON — One of the enduring mysteries of the Covid-19 pandemic, a global health crisis that has led to over 6 million fatalities, is that children have been spared by the virus — for the most part — and have not experienced anywhere near the severity of illness that adults have.

Scientists struggled to find out how the virus spread and hospitals tried different methods to help the most ill Covid patients.

It was fortunate that very few of these patients were children. This left public health professionals puzzled as to how and why they didn’t see their kids become seriously ill with Covid.

Although scientists aren’t quite sure why Covid is not affecting children, studies slowly reveal how and why the children’s reactions to Covid are different from adults.

“A number of theories have been suggested, including a more effective innate immune response, less risk of immune over-reaction as occurs in severe Covid, fewer underlying co-morbidities and possibly fewer ACE-2 receptors in the upper respiratory epithelium — the receptor to which SARS-CoV-2 [Covid] binds,” Dr. Andrew Freedman, an academic in infectious diseases at the U.K.’s Cardiff University Medical School, told CNBC in emailed comments, adding that nonetheless the phenomenon was not “fully understood.”

Although he said more research would be needed to find a definitive answer for the question, evidence already exists that Covid is a less dangerous substance than previously thought.

In particular, the risk increases for people in their 50s and increases again for those in their 60s, 70s, and 80s, the Centers for Disease Control and Prevention saysThe most susceptible to getting sick are those aged 85 or older. Being healthy is key. certain underlying medical conditionsAdults are also more susceptible to becoming severely ill.

Recent studies have shown fundamental differences in the immune responses of children and adults to Covid.

Researchers at the University College London (Wellcome Sanger Institute) conducted this research. and published in the Nature journal in December, found a stronger “innate” immune response in the airways of children, characterized by the rapid deployment of interferons — which are released in the presence of viral or bacterial threats and help to restrict viral replication early on — UCL said.

The researchers also observed that adults had a more rapid immune response, meaning the virus could infiltrate areas within the body that are harder to treat.

CNBC’s Kristin Mondy told CNBC she was the chief of infectious diseases for the Dell Medical School in Texas. “Among the numerous hypotheses that are currently floating in the literature,” the most convincing evidence is that children exhibit a stronger immune response than adults. In particular, in their nasal mucosal tissue, immune cells can rapidly eliminate the virus and more quickly control it.

“Despite this, it is known that the Multisystem Inflammatory syndrome, which results in an excessive immune response to Covid-19 in children, is more common than in adults. It causes inflammation to other organs (e.g the heart/circulatory and the gastrointestinal tract).

Research published in late 2021Examining the risk of the virus for children revealed that it was extremely low for most children and youth below the age 18.

The study, carried out by researchers from several British universities, studied deaths among children and young people in England from March 2020 to February 2021 — the first year of the pandemic — differentiating between those who died of Covid and those who died of an alternative cause but had coincidentally tested positive for the disease.

The study found that 25 of the 3105 young children and adults who died due to all causes in England during the first year of pandemic in England had been killed by Covid. This corresponds to an average mortality rate of 2 per million in England.

One-third of the children who succumbed to Covid had longstanding health problems, with some suffering from multiple conditions and even life-threatening conditions.

Researchers cautioned that although the six other children who died did not appear to be suffering from any underlying medical conditions, there was a possibility of an undiagnosed or unidentified predisposition for severe Covid infections.

Although the risk of death for children overall was low, the study noted that people over the age 10 and from Asian and Black backgrounds as well as those suffering from comorbidities (neurological disorders were the most prevalent comorbidity) were significantly more common in mortality rates than children of other races.

Even among children who have underlying conditions, Covid is “very rarely fatal”. Indeed, within the year that was studied, an estimated 469,982 children in England had Covid, meaning that a child’s chance of surviving an infection was found to be 99.995%.

Data from the U.S. on Pediatric Covid cases and deaths show similar risks for children.

Last week, the U.S. Centers for Disease Control and Prevention announced that 966,575 Americans died due to Covid exposure during the current pandemic. Between 2020 and 2022 there were 921 deaths among 0-17 year olds that were caused by CovidOut of the 73 508 deaths that occurred in this age bracket, 63,508 were due to all causes.

The pandemic started with 19% of the Covid cases occurring in children. according to the American Academy of Pediatrics’ latest state-based data summary publishedLast week, however, the academy stated that children accounted for 0.00% to 0.277% of all Covid-19-related deaths. Only 3 states had reported no child deaths.

Around a fifth of all Covid cases still involve children. In fact, for the week ending on March 17, 18,3% of reported weekly Covid cases involved children. Under-18-year-olds make up 22.2% in the U.S.