Children ‘need jab’ against Covid, study finds

Children’s immunity to Covid-19 is robust at first but doesn’t stand up when reinfection occurs highlighting the need for children to be vaccinated against the virus, study finds.

SARS-CoV-2 viruses.

Children’s immunity to Covid-19 is robust at first but doesn’t stand up when reinfection occurs, highlighting the need for children to be vaccinated against the virus, research by Australian scientists has found.

Scientists at the Garvan Institute of Medical Research in Sydney found children’s immune systems are primed to fight off new infections quickly but this had the payoff that their immune systems do not remember the virus.

The study examined a type of white blood cell, called T cells, and how they responded to the SARS-CoV-2 virus to track immunity in adults and children who contracted Covid-19.

Garvan precision immunology program co-lead Tri Phan, who co-authored the paper, said children had what was called a “naive” immune system because they haven’t had to respond to many viruses before.

“Their immune systems are really primed so that when they get infected with a virus they get over it very, very quickly,” he said. “And so we then start asking the question how has that been impacting on the ability of the kids’ immune response to generate memory?

“Memory is really important because memory is what protects you the next time around when you get infected again with the virus.”

Professor Phan said scientists had studied the number of receptors on T cells to measure immunity in adults and children with the same severity of disease.

“Essentially, what we were able to do is we were able to track a type of white blood cell, called a T cell, and we could track whether it was able to respond to the SARS-CoV-2 virus or not through the receptor that it has,” he said.

“So every T cell has a unique receptor that allows us to recognise specific parts of the virus.

“ … we are infected with all sorts of different viruses all the time such as the common cold viruses, the flu virus and respiratory syncytial virus.

“The way our immune system tells all these viruses apart is because they encode all these receptors of the T cells used to distinguish them. So by tracking the receptors on the T cells, we can then determine what the T cells were doing.”

Professor Phan said the study indicated the importance of children being vaccinated as their immune response would wane on their second infection.

“The thinking used to be that it wouldn’t be a problem for children to be exposed to the virus and maybe that might help them over time to develop immunity,” he said.

“Our concern here is that because the kids, when they do get infected, don’t seem to generate good memory T cell responses, that means that they’re at risk of getting infected again.”

The results showed that infected children were not generating sufficient T cell memory while adults who were in the same household were able to generate memory.

The paper was originally published in Clinical Immunology.