Children and adults produce different types and amounts of antibodies in response to infection with the new one coronavirus, SARS-CoV-2, has completed a new study conducted by researchers from the Faculty of Physicians and Surgeons at Columbia Vagelos University, USA.
The differences in antibodies suggest that the course of infection and the immune response to the new coronavirus is different in children, which could explain why most children easily clear the virus from their bodies.
“Our study provides a thorough examination of SARS-CoV-2 antibodies in children, revealing a strong contrast to adults,” said the immunologist. Farber woman, of Columbia University.
“In children, the infectious course is much shorter and probably not as widespread as in adults,” he added. Matteo Porotto, of the Columbia Department of Pediatrics, who together with Donna Farber conducted the investigation. “Children can eliminate this virus more efficiently than adults and may not need a strong antibody immune response to get rid of the virus.”
Children less affected by SARS-CoV-2
One of the most striking manifestations of the COVID-19 pandemic is that most children cope well with the virus, while older people often struggle with great hardship and serious consequences.
“This is a new infection for everyone,” Donna Farber said, “but children are particularly good at seeing pathogens for the first time. This is what your immune system is designed for. Children have a lot of T cells. able to recognize all kinds of new pathogens, while older people are more dependent on immune memories. We are unable to respond to a new pathogen such as children. “
Children with fewer neutralizing SARS-CoV-2 antibodies
The study involving children and adults infected with COVID-19 led to the conclusion that children produced fewer antibodies against the protein than adults. peak virus – which the virus uses to infect human cells. The children’s antibodies had less neutralizing activity, while all adults, including young adults in their 20s, produced neutralizing antibodies. The sickest adults had the most neutralizing activity.
While it may seem counterintuitive that the sickest patients produce antibodies with the highest neutralizing activity, Donna Farber said this likely reflects the amount of time the virus has been present in the sickest patients.
“There is a connection between the magnitude of the immune response and the extent of the infection: the more severe the infection, the more robust the immune response, because more immune cells and immune reactions are needed to eliminate a higher dose. of a pathogen “.
Other differences in antibodies show that childhood infections are limited
Unlike the adults, the children also produced few antibodies against a viral protein that is only visible to the immune system after the virus has infected human cells. Which “suggests that, in children, the infection doesn’t spread much and doesn’t kill many of the cells,” Donna Farber said.
“Because babies clear the virus naturally and quickly, they don’t have a generalized infection and don’t need a strong antibody response,” said Matteo Porotto.
The reduced course of infection in children may mean that they are infectious for a shorter period than adults and therefore are less likely to spread the virus, although the researchers did not measure viral loads in children.
“Current studies in other countries indicate that school-age children are not carriers of the novel coronavirus, so our data are consistent with these findings,” said Donna Farber.
Children can respond well to the vaccine
The antibody responses found in children do not suggest that children will have a weaker response to a vaccine, the researchers say. Vaccines under development for SARS-CoV-2 contain fragments of the virus and do not mimic the normal route of infection.
“Although infants do not produce neutralizing antibodies in response to a natural SARS-CoV-2 infection, vaccines are designed to generate a protective immune response in the absence of infection,” said Donna Farber. “Children respond very well to vaccines and I think they will develop good neutralizing antibody responses to the SARS-CoV-2 vaccine, and will likely be more protected than adults.”
What is missing from the adult immune system?
Although the findings suggest that the course of infection in children and adults is different, it remains to be seen how children are able to clear the virus more easily and what the adult immune system lacks.
Donna Farber, Matteo Porotto, and other Columbia University researchers are now looking for differences in the response of T lymphocytes (the antibodies produced by the B lymphocytes of the immune system), specifically the T lymphocytes that reside in the lung. Bearing in mind that previous investigations by the Farber lab have shown that these “staying at home” T cells are more important in fighting lung infections than the T cells that travel through the body through the bloodstream. “
Infants infected with SARS-CoV-2 may also generate a stronger response from the innate immune system, which implements interferon and macrophage cells to indiscriminately attack pathogen-infected cells. Previous studies suggest that the innate immune response may be delayed in adults infected with SARS-CoV-2.
“If the innate response is really strong, it can reduce the viral load in the lungs, and the antibodies and T cells in the adaptive response have less to eliminate,” Donna Farber said.
It is also possible that the virus is less able to infect children’s cells, possibly because children’s cells express fewer proteins than the virus needs to infect human cells.
Columbia University researchers are now testing these possibilities with cells from children and adults.
“There are still all these issues that we have very little information about,” Porotto said. “The interaction between the virus and the host is why we see so much diversity in responses to this virus, but we still don’t understand enough to really determine what leads to serious disease and what leads to minor disease.”