Friday, October 15

Children are protected against severe COVID by their innate immune systems

Up to one third are asymptomatic.

Up to one third are asymptomatic.

The children are protected against severe Covid-19 because his innate immune system is rapidly attacking the new SARS-CoV-2, according to research led by the Murdoch Children’s Research Institute (MCRI) in Australia.

The study, published in ‘Nature Communications’, included a analysis of blood samples from 48 children and 70 adults in 28 Melbourne households infected or exposed to the new coronavirus. Immune responses were monitored during the acute phase of infection and for up to two months thereafter.

For the first time, the reasons why children have mild Covid-19 disease compared to adults have been observed, and the immunological mechanisms that support this protection. “They were unknown until this study,” said MCRI’s Dr. Melanie Neeland.

“The children have less likely to be infected with the virus and up to a third are asymptomatic, which is strikingly different from the higher prevalence and severity seen in children for most other respiratory viruses, “he added.

In his view, understanding the underlying age-related differences in severity of Covid-19 will provide important insights and opportunities for prevention and treatment, both for COVID-19 and potential future pandemics.

Francesca Orsini and Alessandro Bartesaghi participated in the study along with their two daughters, Beatrice and Camilla, after they all tested positive for Covid-19. Both daughters, six and two years old, they only had a mild runny nose, but Francesca and Alessandro had extreme fatigue, headaches, muscle aches, and loss of appetite and sense of taste. It took Francesca and Alessandro at least two weeks to fully recover.

The study showed that children with COVID-19 have a more robust innate immune response to the virus compared to adults. “Coronavirus infection in children was characterized by the activation of neutrophils, the specialized white blood cell that helps heal damaged tissues and resolves infections, and a reduction in first-responder immune cells, such as monocytes, dendritic cells and natural killer cells in the blood, “he explained.

This suggests that, he explains, “these immune cells that fight infection are migrating to infection sites, quickly eliminating the virus before it has a chance to really take root. This shows that the innate immune system, our first line of defense against germs, is crucial to preventing severe Covid-19 in children. Importantly, this immune reaction was not replicated among the adults in the study. ”

The study also found that children and adults who were exposed, but tested negative for the coronavirus, also had altered immune responses. “Both children and adults had increased numbers of neutrophilsup to seven weeks after exposure to the virus, which could have provided a level of protection against the disease, “he noted.

The study confirms previous MCRI research that found that three children from a Melbourne family developed a similar immune response after prolonged exposure to the coronavirus from their parents. The research indicated that although the children had been infected with the coronavirus, they were able to mount an immune response that was highly effective in stopping the virus from replicating, meaning that they never tested positive.

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