Team reveals why children’s immune response to COVID-19 is better than adults’

Researchers have revealed that children and adults exhibit distinct immune system responses to infection by SARS-CoV-2, which causes COVID-19. They say that this finding helps explain why COVID-19 outcomes tend to be much worse in adults.

The research was conducted at Yale University and the Albert Einstein College of Medicine, both US.

A widespread and dangerous immune response to the virus has been linked to acute respiratory distress syndrome (ARDS), the need for ventilation and increased mortality in adults with COVID-19. The team highlight that these outcomes are less common in children, which has led to speculation that immune system response to the virus is somehow suppressed.

The new study investigated variations in the types of immune system responses in patients who experienced different health outcomes from the novel coronavirus. The team examined serum and cell samples obtained from paediatric and adult patients diagnosed with COVID-19 and found that children express higher levels of two specific immune system molecules: interleukin 17A (IL-17A), which helps to mobilise immune system response during early infection and interferon gamma (INF-γ), which combats viral replication. The younger the patient, the higher the levels of IL-17A and INF-γ the analysis showed.

“To our surprise, we found these particular serum cytokines were at higher levels in children than adults,” said Professor Kevan Herold, co-senior author of the paper.

According to the researchers, IL-17A and INF-γ are part of the innate immune system – a more primitive, non-specific type of response activated early after infection. Conversely, the adults showed a more vigorous adaptive immune system response including higher neutralising antibody levels, which record signatures of pathogens and target them for elimination.

From their results, the team suggest that boosting certain types of immune responses may be beneficial to patients with COVID-19.

“The suggestion is that children have a more robust, earlier innate immune response to the virus, which may protect them from progressing to severe pulmonary disease,” said co-senior author Professor Betsy Herold.

The study was published in Science Translational Medicine.