COVID-19 Infection in Children Has a Shorter Duration Than Adults

Children are able to more effectively clear the infection due to the new coronavirus SARS-CoV-2 that leads to COVID, according to the new study by researchers at the Columbia University Vagelos College of Physicians and Surgeons, this is because children and adults produce different types and amounts of antibodies.

This study shows that the most of the children are able to easily clear the virus from their bodies and the difference in the antibodies seen in adults and children show that the course of the infection and immune response is different in children.

‘Children are able to more effectively clear the infection due to difference in antibodies type and amount and also because of innate immune system. The course of COVID-19 infection is shorter in children as compared to adults. Vaccines will be as effective in children as in adults.’

"Our study provides an in-depth examination of SARS-COV- 2 antibodies in kids, revealing a stark contrast with adults," said Donna Farber, PhD Immunologist at Columbia University, the George H. Humphreys II Professor of Surgical Sciences in the Department of Surgery, who led the study along with Matteo Porotto, PhD, associate professor of viral molecular pathogenesis in the Pediatrics Department of Columbia.

The first authors, Stuart Weisberg MD, PhD, assistant professor of pathology & cell biology, and Thomas Connors MD, assistant professor of pediatrics were responsible for enrolling the patients into the study and conducting data analysis.

Unique Response to COVID 19 Infection in Children

Porotto added, "In kids, the infectious course is much shorter and probably not as disseminated as in adults, kids may clear this virus more efficiently than adults and they may not need a strong antibody immune response to get rid of it."

During this Covid-19 pandemic it was observed that most of the children were able to cope well with the virus while most of the adults struggled. Farber said, "This is a new infection for everybody, but children are uniquely adapted to see pathogens for the first time. That's what their immune system is designed to do. Children have a lot of naive T cells that are able to recognize all sorts of new pathogens, whereas older people depend more on our immunological memories. We're not as able to respond to a new pathogen like children can."

There were 47 children who were enrolled in this study, out of which 16 children were treated at Columbia University Irving Medical Center for MIS-C and 31 children who were of similar ages who tested positive after visiting the medical centre for treatment of other conditions. No Covid-19 symptoms were observed in almost half of the children without MIS-C. There were 32 adults enrolled in this study which included severely affected patients admitted in hospital to those with milder disease who recovered at home.

The study found that the adults produced different antibody profile than both the groups of children. When compared with adults, it was observed that the children produced fewer antibodies against virus's spike protein and it also had the least neutralizing activity while adults produced neutralizing antibodies (antibodies that defends cell from the infectious agent) and the sickest adults produced the most neutralizing activity.

Farber says, "There is a connection between the magnitude of your immune response and the magnitude of the infection: The more severe the infection, the more robust the immune response, because you need to have more immune cells and immune reactions to clear a higher dose of a pathogen."

When compared to adults, it was observed that children produced very few antibodies against the viral protein which is recognized by the immune system only after the virus infects the human cells.

Farber said, "That suggests that in kids, the infection doesn't really spread a lot and doesn't kill a lot of their cells. "Porotto said, "Because children clear the natural virus rapidly, they do not have a widespread infection and they do not need a strong antibody response."

Though the researchers did not measure the viral load in the children but they are less likely to spread the virus as they are infectious for a shorter period when compared with adults due to the reduced course of infection.

Farber said, "Current studies in other countries indicate that younger school-age children are not vectors for the new coronavirus, so our data are consistent with those findings".

Vaccine for COVID-19 and its likely Effect on Children

The researchers have said that even though such an antibody response was seen in children, it does not indicate that children will have a weaker response to the vaccine, as the vaccines which are currently under development for SARS-CoV-2 does not mimic the normal route of infection but contains fragments of the virus.

Farber said, "Even though children don't produce neutralizing antibodies in response to a natural infection with SARS-CoV-2, vaccines are designed to generate a protective immune response in the absence of an infection. Children respond very well to vaccines, and I think they will develop good neutralizing antibody responses to a SARS-CoV-2 vaccine, and they'll probably be better protected than the adults. That said, very few vaccine studies are currently enrolling children and we will need this data to really understand how well the vaccines work in children."

As the course of infection in children and adults is different, researchers are still not able to identify what the adult immune system lacks and how the children's immune system is able to clear the infection more easily.

The researchers are now studying the differences in the T cell response (essential in immune response and stimulate production of antibodies) specifically the T cells which are present in the lungs.

It was also observed that children infected with SARS-CoV-2, also generates a stronger response from the innate immune system (barriers that keep harmful materials from entering the body) to attack the infection where as this innate immune may be delayed in adults.

Farber said, "If the innate response is really strong, that can reduce the viral load in the lungs, and the antibodies and T cells of the adaptive response have less to clear up."

Another possibility is that the children's cells contain fewer of the protein which the virus needs to infect the human cells. Researchers at Columbia are now studying all these different possibilities.

Porotto said, "There are still all these issues that we have very little information about. The interaction between the virus and the host is the reason why we see so much diversity in responses to this virus, but we don't understand enough about this virus yet to really determine what leads to severe disease and what leads to mild disease."

Source: Medindia