One of the coronaviruses that cause the common cold helps to boost children’s immunity against COVID-19, according to a new Swedish study.
Researchers at Karolinska Institutet say having identified OC43 as boosting the immune response to COVID-19 could help with the development of more tailored vaccine programmes for both children and adults.
The discovery came about after medical doctors and researchers noticed that children and adolescents infected with COVID-19 became less ill than adults.
One possible explanation was that children already had a prior level of immunity to COVID-19 provided by memory T cells generated by common colds.
The research team from the Karolinska Institutet studied blood samples from children taken before the pandemic and identified memory T cells that react to cells infected with SARS-CoV-2.
These findings, published in PNAS, show how T cells previously activated by the OC43 virus can cross-react against SARS-CoV-2.
Corresponding author Annika Karlsson, research group leader at the Department of Laboratory Medicine, Karolinska Institutet, said: “These reactions are especially strong early in life and grow much weaker as we get older.
“Our findings show how the T-cell response develops and changes over time and can guide the future monitoring and development of vaccines.”
The results show that the memory T-cell response to coronaviruses develops as early as two years.
The study, which involved researchers from the universities of Bern, in Switzerland, Oslo, in Norway, and Linköping, in Sweden, was based on 48 blood samples from two- and six-year-olds, and 94 samples from adults between the ages of 26 and 83. The analysis also included blood samples from 58 people who had recently recovered from COVID-19.
The team wants to continue its research by undertaking analogous studies of younger and older children, teenagers and young adults to better track how the immune response to coronaviruses develops from childhood to adulthood.
Humbert M, Olofsson A, Wullimann D et al. Functional SARS-CoV-2 cross-reactive CD4+ T cells established in early childhood decline with age. PNAS 13 March 2023; doi: 10.1073/pnas.2220320120.
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