Project Title

Assessing cross-reactive and pre-existing immunity to SARS-CoV-2 in adolescents

EDCTP Project Call

Career Development Fellowship (CDF)

Project Objectives

1. To examine pre-existing antibody responses to SARS-CoV-2 in unexposed South African adolescents. 2. To assess pre-existing T cell immune responses to SARS-CoV-2 in unexposed adolescents. 3. To compare antibody and T cell responses to SARS-CoV-2 between recovered adolescents and adults.

Study Design

Observational

Project Summary

COVID-19 has resulted in more than 15 million excess deaths worldwide. Although vaccines are now available, immunisation coverage remains low, particularly in Africa. Consequently, strategies for prevention, treatment, and diagnosis are still urgently needed to reduce the disease burden of COVID-19. Although significant scientific advances have been made, key questions still remain, particularly in the context of disease severity and pre-existing immunity. Pre-existing and cross-reactive T cell responses to SARS-CoV-2 have been described in unexposed adults, likely due to memory responses from previous endemic coronavirus infections. Given that children and adolescents have milder COVID-19 disease compared to adults, we hypothesise that this may be due to higher pre-existing immunity to SARS-CoV-2 from more recent or frequent infections with common cold coronaviruses. This study also hypothesises that adolescents who have recovered from COVID-19 will have greater immunity to SARS-CoV-2 than recovered adults since pre-existing responses may be boosted by SARS-CoV-2 infection. Antibody responses to endemic coronaviruses were measured to estimate the rate of exposure in South African adolescents. Adults had higher antibody responses to 2/4 endemic coronaviruses, namely HKU-1 and OC43, suggesting differences in circulating viruses. Similar to the global north, pre-pandemic antibody responses to SARS-CoV-2 were rare, detected in less than 4% of samples (7/182). Antibody and T cell responses to SARS-CoV-2 were compared between adolescents and adults who have recovered from COVID-19 to investigate whether pre-existing responses in adolescents may be boosted by subsequent SARS-CoV-2 infection, resulting in higher responses than adults. Interestingly, we found that adolescents had consistently lower T cell responses to SARS-CoV-2, although they had more exposures from multiple waves of infection. These important findings highlight the need to study different age groups, particularly adolescents, who are typically understudied.

Host Organisation

Current Organisation

University of Cape Town

Current Job Title

Junior Research Fellow

Biography

Ruby is an infectious disease immunologist based in Cape Town, South Africa. Her research focuses on immunity in at-risk populations. She is passionate about science communication and advocates for better mental health in academia.

Publications