Learning from inborn errors of immunity and secondary immune deficiencies about vaccine immunogenicity, efficacy, and safety.

Since its discovery in the late 18th century, the role of vaccination in preventing death and disease has expanded across many infectious diseases and cancer. Key to our understanding of vaccine immunogenicity and efficacy is knowledge of the immune system itself. Inborn errors of immunity (IEI) represent a heterogeneous group of disorders characterized by impaired function of the immune system. Patients with IEI can have variable responses to vaccinations, depending on the nature and extent of the defect. Studies performed during the recent COVID-19 pandemic have brought unique insight into vaccine immunogenicity in individuals with IEI, knowledge that can be extended to the growing number of patients with secondary immunodeficiency arising from malignancy, organ transplantation, autoimmune conditions, and their treatments. In this review, we describe vaccine immunogenicity in IEI alongside their equivalent secondary immunodeficiencies and discuss what lessons can be learned about immunization strategies more broadly.