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Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease , has spurred a global health crisis. To date, there are no proven options for prophylaxis for those who have been exposed to SARS-CoV-2, nor therapy for those who develop COVID-19. Immune (i.e. "convalescent") plasma refers to plasma that is collected from individuals, following resolution of infection and development of antibodies. Passive antibody administration through transfusion of convalescent plasma may offer the only short-term strategy to confer immediate immunity to susceptible individuals. There are numerous examples, where convalescent plasma has been used successfully as post-exposure prophylaxis and/or treatment of infectious diseases, including other outbreaks of coronaviruses (e.g. SARS-1, Middle East Respiratory Syndrome [MERS]). Convalescent plasma has also been used in the COVID-19 pandemic; limited data from China suggest clinical benefit, including radiological resolution, reduction in viral loads and improved survival. Globally, blood centers have robust infrastructure to undertake collections and construct inventories of convalescent plasma to meet the growing demand. Nonetheless, there are nuanced challenges, both regulatory and logistical, spanning donor eligibility, donor recruitment, collections and transfusion itself. Data from rigorously controlled clinical trials of convalescent plasma are also few, underscoring the need to evaluate its use objectively for a range of indications (e.g. prevention vs treatment) and patient populations (e.g. age, comorbid disease). We provide an overview of convalescent plasma, from evidence of benefit, regulatory considerations, logistical work flow and proposed clinical trials, as scale up is brought underway to mobilize this critical resource.

The late twentieth century witnessed the emergence of numerous infectious diseases that are caused by microorganisms that rarely cause disease in normal, healthy immunocompetent hosts. The emergence of these diseases shows that the existing concepts of pathogenicity and virulence do not take into account the fact that both the microorganism and the host contribute to microbial pathogenesis. To address this impediment to studies of host-microorganism interactions, we propose a new theoretical approach to understanding microbial pathogenesis, known as the 'damage-response' framework.

Antibody-based therapies are currently undergoing a renaissance. After being developed and then largely abandoned in the twentieth century, many antibody preparations are now in clinical use. However, most of the reagents that are available target non-infectious diseases. Interest in using antibodies to treat infectious diseases is now being fuelled by the wide dissemination of drug-resistant microorganisms, the emergence of new microorganisms, the relative inefficacy of antimicrobial drugs in immunocompromised hosts and the fact that antibody-based therapies are the only means to provide immediate immunity against biological weapons. Given the need for new antimicrobial therapies and many recent technological advances in the field of immunoglobulin research, there is considerable optimism regarding renewed applications of antibody-based therapy for the prevention and treatment of infectious diseases.

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