Immune Resilience to SARS-CoV-2 Infection by Shifting Risk Within Normal and Disease Populations

ABSTRACT: The idea of a Common Mucosal Immune system (CMS) is 50 years old. Its relevance to immune protection at mucosal sites and its potential to modulate the impact of vaccination-induced protection against infection of the airway, has been poorly understood. The consequent failure of current SARS-CoV-2 vaccination to satisfy expectations with respect to prevention of infection, viral transmission, duration of protection and pattern of clinical protection, led to public health and medical decisions now under review. This review summarises knowledge of the CMS in man, including the powerful role it plays in immune protection and lessons with respect to what can and can not be achieved by systemic and mucosal vaccination for prevention of airway infection. The powerful impact in both health and disease of optimising delivery of immune protection using selected isolates from the respiratory microbiome, is demonstrated through review of randomised controlled trials (RCT’s) in subjects with chronic airway disease, and in otherwise healthy individuals with risk factors, in whom the idea of mucosal immune resilience is introduced.