Exposure to a common seasonal coronavirus stimulates a memory T cell response that protects children against COVID-19. However, this immune response peaks at age 6.
Child Sneeze | Image Credit: © ryanking999 - © ryanking999 - stock.adobe.com.
Throughout the COVID-19 pandemic, children have experienced less severe disease progression than adults. Some investigators hypothesize this is due to common colds helping children generate memory CD4+ T cells that provide a level of immunity against COVID-19.
A team of researchers from the Karolinska Institutet in Sweden wanted to determine whether contracting OC43, 1 of the 4 coronaviruses responsible for seasonal colds, stimulates a T cell response that protects children against COVID-19.
The investigators assessed humoral and cellular immune responses against OC43 and COVID-19 in children and adults who had never been exposed to COVID-19. They collected 48 blood samples from 2- and 6-year-old children, and 94 samples from adults aged 26-83 years. As a control, the study also included blood samples from 58 individuals who had recently recovered from COVID-19.
The investigators found preexisting COVID-19 reactive CD4+ T cell responses targeting spike, nucleocapsid, and membrane were closely linked to the frequency of OC43-specific memory CD4+ T cells in childhood.
This is evidence that functional cross-reactive memory CD4+ T cell immunity against COVID-19 is established during early childhood, similar to early seroconversion with seasonal human coronavirus OC43.
The study authors wrote that compared to other viruses, the high OC43 seroprevalence at age 2 suggests memory responses to coronaviruses develop at a young age. However, unlike other viruses, these OC43-specific antibodies did not increase further with age. “These reactions are especially strong early in life and grow much weaker as we get older,” said Annika Karlsson, a study author and research group leader at the Karolinska Institutet Department of Laboratory Medicine.
The robustness of the memory CD4+ T cell responses peaked at age 6 and then declined with age. The investigators concluded that these age-dependent qualitative differences in preexisting COVID-19-reactive T cell responses may reflect an individual’s ability to control coronavirus infections and mount an immune response to vaccination.
This article was initially published by our sister publication Contagion Live.
Communication, planning, and vaccines prevent infections in the school setting
July 16th 2024Donna Hallas. PhD, PPCNP-BC, CPNP, PMHS, FAANP, FAAN, underscores the critical need for proper vaccination and effective communication between parents and schools to ensure sick children stay home, while addressing logistical challenges faced by parents.