March 22 (UPI) -- Children age 10 and younger develop a more robust immune response to the coronavirus than other age groups, a study published Monday by JAMA Network Open found.
Blood of younger children tested for antibodies to the virus had evidence of more than twice as many cells created by the immune system to fight off infections than adolescents and young adults, the data showed.
Similarly, adolescents displayed higher antibody levels than young adults, the researchers said.
Antibody levels declined with age, with study participants age 80 and older having the lowest, according to the researchers.
The findings help explain why most children experience mild cases of COVID-19, often with no symptoms, while older adults get more seriously ill after infection, they said.
"Children infected with [COVID-19] are more likely to manifest mild symptoms and are at a lower risk of developing severe respiratory disease compared with adults," study co-author Sarina H. Yang told UPI in an email.
"Our findings suggest that the differences in the clinical manifestations of COVID-19 in pediatric patients compared with adult patients could be partly due to age-related immune responses," said Yang, a pathologist at Weill Cornell Medicine in New York City.
For this study, Yang and her colleagues analyzed nearly 32,000 blood samples collected at the medical center between April and August of last year.
About 1,200 of the samples were from children and teens age 19 and younger, with the remainder coming from adults.
Of the pediatric samples, 17% tested positive for COVID-19 antibodies, while 19% of adult participants tested positive.
Children age 10 and younger who tested positive for antibodies had more than double the amount of immunoglobulin G, a key antibody, than adolescents age 11 to 18.
In addition, they had nearly six times the amount of immunoglobulin G as young adults age 18 to 24.
Through March 17, children from infancy through age 17 years have accounted for 226 of the nearly 518,000 deaths caused by COVID-19 in the United States, according to the Centers for Disease Control and Prevention.
It is likely that this is due to their enhanced antibody response to the virus, according to Yang and her colleagues.
"Our data could partly explain the overall lower rate of symptoms and cases of severe disease in children infected with [COVID-19]," co-author Zhen Zhao told UPI in an email.
"Since there are no vaccines available yet for the pediatric population, measurements of antibody quantity and quality could assist in guiding rational vaccine choice and deployment based on age," said Zhao, who also is a pathologist at Weill Cornell Medicine.