Children infected with the coronavirus produce weaker antibodies and fewer types of them than adults do, suggesting they clear their infection much faster, according to a new study published Thursday.
Other studies have suggested that an overly strong immune response may be to blame in people who get severely ill or die from Covid-19. A weaker immune response in children may paradoxically indicate that they vanquish the virus before it has had a chance to wreak havoc in the body, and may help explain why children are mostly spared severe symptoms of Covid, the disease caused by the coronavirus. It may also show why they are less likely to spread the virus to others.
“They may be infectious for a shorter time,” said Donna Farber, an immunologist at Columbia University in New York who led the study reported in the journal Nature Immunology.
Having weaker and fewer antibodies does not mean that children would be more at risk of re-infections, other experts said.
“You don’t really need a huge, overly robust immune response to maintain protections over some period of time,” said Deepta Bhattacharya, an immunologist at the University of Arizona in Tucson. “I don’t know that I would be especially worried that kids have a little bit lower antibody response.”
The study looked at children’s antibody levels at a single point in time, and was too small to provide insights into how the levels may vary with age. But it could pose questions for certain antibody tests that may be missing children who have been infected.
Dr. Farber and her colleagues analyzed antibodies to the coronavirus in four groups of patients: 19 adult convalescent plasma donors who had recovered from Covid without being hospitalized; 13 adults hospitalized with acute respiratory distress syndrome resulting from severe Covid; 16 children hospitalized with multi-system inflammatory syndrome, the rare condition affecting some infected children; and 31 infected children who did not have the syndrome. About half of this last group of children had no symptoms at all.
Individuals in each group had antibodies, consistent with other studies showing that the vast majority of people infected with the coronavirus mount a robust immune response.
“This further emphasizes that this viral infection in itself, and the immune response to this virus, is not that different from what we would expect” from any virus, said Petter Brodin, an immunologist at Karolinska Institutet in Stockholm.