- Growing evidence is showing that COVID-19 affects kids differently than adults.
- Children experience lower infection rates, accounting for less than 10 percent of cases in the United States.
- Infectious disease specialists say there are several factors that seem to protect children: immunity to seasonal coronaviruses, underdeveloped sinuses, and fewer chronic health conditions.
A new model from researchers in Israel found that kids are half as susceptible to COVID-19 compared to adults.
The report published Thursday, Feb. 11, in PLOS Computational Biology also found that people under 20 are less likely to transmit the virus to other people.
Growing evidence has showed that COVID-19 affects kids and younger people differently.
Children experience lower infection rates, accounting for less than 10 percent of cases in the United States.
When kids do get the disease, the symptoms are typically milder.
They also appear to transmit the virus less and are not primary drivers of community transmission.
Dr. Sharon Nachman, the chief of the Division of Pediatric Infectious Diseases at Stony Brook Children’s Hospital, said the lower rates of infection in kids are likely due to many factors.
“These could include a different immune response to virus as compared to adults, the frequent lack of comorbid conditions in many children, and ongoing/frequent exposures to other coronaviruses, and possibly some cross-variant nonspecific immunity,” Nachman said.
What the modeling found
The researchers evaluated transmission data of 637 households in Bnei Brak, Israel.
All individuals underwent PCR testing, and some of the participants were given serological antibody tests.
The researchers then took those findings and adjusted them to reflect the coronavirus’s overall infection and transmission rates.
They found that kids are 43 percent as susceptible to COVID-19 compared to adults.
The findings suggest kids transmit COVID-19 far less than adults. That is, the ability of children to pass the virus is about 63 percent compared to adults.
Children are also less likely to produce positive PCR tests, which looks for genetic material of the virus, even when they have the virus.
This could explain why kids have lower diagnosis rates across the globe.
“After monitoring the [COVID-19] pandemic for over a year, the data are clear,” said Dr. Robert Hamilton, a pediatrician at Providence Saint John’s Health Center, “children have been spared the ravages of this illness.”
“Around the world, study after study has shown that children and adolescents account for only 1 to 3 percent of all cases, and that even fewer ultimately required hospitalization,” Hamilton said.
Why are kids less susceptible to COVID-19?
Dr. Amy Baxter, a clinical associate professor at the Medical College of Georgia at Augusta University, and CEO of PainCareLabs, suspects children are less affected by COVID-19 because of their underdeveloped sinuses.
“SARS-CoV-2 replicates in the nasopharynx, and children have extremely underdeveloped sinuses until about age 12,” Baxter told Healthline.
Baxter pointed out that even when children test positive for COVID-19, they may be less likely to transmit SARS-CoV-2.
“Even if the swab seems to show the same viral load, the tank size is so much different that kids’ immune systems aren’t triggered in the same way because they likely don’t absorb nearly as many copies of [the] virus,” Baxter said.
SARS-CoV-2 is usually nasally inhaled before it develops into COVID-19. From there, it travels past the nose and into the nasal cavities where the virus latches onto certain receptors called ACE2 and makes copies of itself to create an infection.
Dr. Kathleen Jordan, an infectious disease specialist and senior vice president of medical affairs at the women’s health provider Tia, suspects the lower attack rate in kids has to do with the fact that children generally don’t have as many health conditions or comorbidities as adults.
The Centers for Disease Control and Prevention (CDC)
lists obesity and type 2 diabetes as health conditions that can increase the risk of severe COVID-19.
Jordan thinks it’s a “combination of higher comorbidities in adults that increase their risk while some characteristics unique to children also protect them, such as immune characteristics and decreased propensity to clotting and inflammatory disorders in general.”
But there are many other theories scientists are looking into.
Kids may have higher immunity from other seasonal coronaviruses
that cause the common cold.
“Immunity to these coronavirus cousins of [SARS-CoV-2] viruses seems to confer some protection against [COVID-19] as well,” Hamilton said.
This crossover immunity may keep their immune systems sharp and ready to attack the novel coronavirus.
“It may be that age is the best protection for COVID,” Nachman noted.
There may be differences in microbiota, vitamin D levels, and melatonin that provide some degree of protection.
“These tempered pathways may play a role in why the disease is so much milder in children and less likely to cause symptoms or end organ damage as seen by these pathways in adults,” Jordan said.
What this means for community transmission
More research is needed to better understand kids’ role in transmitting the virus that causes COVID-19, specifically if and how schools and childcare centers fuel transmission.
However, children are not thought to be key drivers of transmission in schools or their communities.
A study from Ireland evaluating 40,000 people found that kids under 15 were half as likely to get and pass the coronavirus.
Still, kids can contract SARS-CoV-2, and COVID-19 spreads wherever humans interact, schools and childcare facilities included.
But given the growing evidence, Hamilton said many researchers and physicians feel the risks of keeping kids out of school — like depression and anxiety — are greater than the risk of contracting the new coronavirus in a school setting.
Podding, physical distancing, and mask wearing are effective measures for mitigating transmission in schools, Jordan noted.
“We have seen that school is the safest place for our children,” Nachman said. “In pretty much each school that is open to in-person learning, and with masking and some part of social distancing, there is almost no transmission of virus.”
The bottom line
A new model from researchers in Israel found that kids are half as susceptible to COVID-19 compared to adults.
They’re also less likely to transmit the illness and tend to produce negative PCR tests even when they have the virus.
Infectious disease specialists say there’s multiple factors that seem to protect children, such as immunity to seasonal coronaviruses, underdeveloped sinuses, and less comorbidities.
Given the evidence, many health experts believe the benefits of in-school learning outweigh the risks of contracting the coronavirus in a school setting.
Still, COVID-19 spreads wherever humans are, so mitigation measures such as face masking, physical distancing, and pod learning can help offset disease transmissions in childcare and learning facilities.
