SARS-CoV-2: Comparing the immune response in children and adults
Written by Lori Uildriks, Pharm.D., BCPS, BCGP on November 16, 2020 — Fact checked by Rita Ponce, Ph.D.
A recent study from researchers at Columbia University Irving Medical Center in New York demonstrated distinct differences between the antibody responses of children and adults with COVID-19. In particular, the differences were seen in the type, amount, and neutralizing activity of antibodies.
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COVID-19 affects children and adults in markedly different ways. Most childrens’ symptoms are similar to those of adults, but generally disease severity is milder in children than it is in adults.
The majority of children with a SARS-CoV-2 infection are asymptomatic or display mild symptoms. Most often, these are cough, fever, or gastrointestinal symptoms.
Infants less than 1 year of age and children with certain underlying medical conditions are at greater risk of developing a severe form of COVID-19.
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In some rare cases, children who develop COVID-19 exhibit a medical condition called multisystem inflammatory syndrome in children (MIS-C). This condition causes inflammation of the eyes, skin, brain, kidneys, lungs, heart, or gastrointestinal tract, sometimes beginning weeks after a person has contracted SARS-CoV-2.
Adults are more likely than children to manifest with severe or critical illness from COVID-19, especially those who are older or those with certain underlying medical conditions, such as obesity, type 2 diabetes, chronic kidney disease, and cancer.
Severe illness often requires hospitalization and may include management of complications such as acute respiratory distress syndrome (ARDS), pneumonia, blood clots, acute kidney injury, sepsis, or cardiomyopathy.
Varying clinical presentation
Scientists do not yet understand why children and adults respond so differently to a SARS-CoV-2 infection.
The recent study set out to investigate the differences in immune responses to SARS-CoV-2 between adults and children. The scientists examined a range of immune components.
People with a SARS-CoV-2 infection and people who have recovered from mild disease display antibodies specific to proteins on the novel coronavirus: spike (S) proteins and nucleocapsid (N) proteins. The S protein of the virus binds to the cell’s receptor, allowing viral entry. The N protein is necessary for replication of SARS-CoV-2.
Anti-S antibodies can effectively neutralize viral activity. Studies investigating their use in vaccines and for treatment of severe COVID-19 disease are currently underway.
In the new study, which appears in Nature Immunology, researchers investigated the type and neutralizing activity of antibody response in a total of 32 adults and 47 children with COVID-19 seen at the New York-Presbyterian/Columbia University Irving Medical Center hospital and the Morgan Stanley Children’s Hospital of New York from March to June 2020.
The study involved two groups of adults and two groups of children. One group of adults comprised 19 convalescent plasma donors (CPD) who recovered from mild COVID-19 respiratory illness without requiring hospitalization. The second adult group included 13 people who were hospitalized with severe COVID-19 ARDS (COVID-ARDS).
The children were aged 3–18 years. The first group included 16 individuals who were hospitalized with MIS-C; the second group comprised 31 children with COVID-19 who did not develop MIS-C (non-MIS-C).
Within the non-MIS-C pediatric group, 48% were asymptomatic.
In both the COVID-ARDS and MIS-C groups, participants had high levels of inflammatory markers called interleukin 6 and C-reactive protein. Those in the COVID-ARDS group also experienced significantly increased levels of ferritin and lactate dehydrogenase than those in the MIS-C group.
Only two children developed ARDS: one in the non-MIS-C and one in the MIS-C group. This illustrates the difference in inflammatory responses and clinical symptoms between adults and children in response to COVID-19, according to the authors of the study.