Trilogy of COVID-19: Infection, Vaccination, and Immunosuppression

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative respiratory pathogen responsible for coronavirus disease 2019 (COVID-19). In 2020, the power of open science was visible to all, as novel vaccinology led to rapid establishment of vaccine clinical trials, and subsequent authorization of SARS-CoV-2 at an unprecedented pace. This evoked rapid deployment of SARS-CoV-2 vaccines and booster doses to keep with the ever-changing landscape of SARS-CoV-2. In this review, we provide an overview of vaccine efficacy studies, which have been well characterized in healthy individuals. Nevertheless, vaccine efficacy within the immunosuppressed is less well characterized, as these individuals were omitted from initial efficacy studies. Consequently, vaccine-induced responses in this group are relatively unknown. Currently, limited evidence investigating vaccine efficacy within the immunosuppressed is available. Here, we provide an overview of SARS-CoV-2 infection and associated pathogenesis. Furthermore, we undertake a critical analysis of observed vaccine responses from clinical studies, conducted in healthy and immunosuppressed populations. Whilst vaccine deployment has curbed mortality, there are significant challenges that lie ahead. This includes correlating vaccine responses with protective immunity and ensuring that global vaccine equity is met.