Age-Related differences in immunological responses to SARS-CoV-2

Yin Wong, Lydia Su; Ling Loo, Evelyn Xiu; Hui Kang, Alicia Yi; Lau, Hui Xing; Tambyah, Paul Anantharajah; Tham, Elizabeth Huiwen

There is a striking age-related disparity in the prevalence and severity of SARS-CoV-2 induced COVID-19 infections, which might be explained by age-dependent immunological mechanisms. These include age-related physiological differences in immunological responses, cross-neutralizing antibodies, differences in levels and binding affinity of ACE-2, the SARS-CoV-2 target receptor; antibody dependent enhancement (ADE) in adults manifesting with an over-exuberant systemic inflammation in response to infection; and the increased likelihood of co-morbidities in adults and the elderly. Emerging immunological phenomena such as PMIS-TS (Paediatric Multi-System Inflammatory Disorder Temporally associated with SARS-CoV-2) or MIS-C (Multisystem Inflammatory Syndrome in Children are now being observed, though the underlying mechanisms are still unclear. Understanding the mechanisms through which pediatric patients are protected from severe novel coronaviruses infections will provide critical clues to the pathophysiology of COVID-19 infection and inform future therapeutic and prophylactic interventions. Asymptomatic carriage in children may have major public health implications which impact on social and healthcare policies on screening and isolation practices, school reopening and safe distancing requirements in the community.