A Dual-Antigen Enzyme-Linked Immunosorbent Assay Allows the Assessment of Severe Acute Respiratory Syndrome Coronavirus 2 Antibody Seroprevalence in a Low-Transmission Setting.

Estimates of seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies have been hampered by inadequate assay sensitivity and specificity. Using an enzyme-linked immunosorbent assay-based approach that combines data about immunoglobulin G responses to both the nucleocapsid and spike receptor binding domain antigens, we show that excellent sensitivity and specificity can be achieved. We used this assay to assess the frequency of virus-specific antibodies in a cohort of elective surgery patients in Australia and estimated seroprevalence in Australia to be 0.28% (95% Confidence Interval, 0-1.15%). These data confirm the low level of transmission of SARS-CoV-2 in Australia before July 2020 and validate the specificity of our assay.

Improved vaccines through targeted manipulation of the body's immunological risk-assessment?

Recent advances have highlighted the outstanding role of the innate immune system for instructing adaptive immunity. Translating this knowledge into successful immunotherapies like vaccines, however, has proven to be a difficult task. This essay is based on the hypothesis that immune responses are tightly scaled to the infectious threat posed by a given microbial stimulus. A meticulous immunological risk-assessment process is therefore instrumental for eliciting well-balanced responses and maintaining immune homeostasis. The immune system makes fine distinctions, for example, between live and dead bacteria, or pathogenic and non-pathogenic microorganisms. Here, I discuss recent evidence for some of the mechanisms underlying these distinctions and speculate on strategies for therapeutically targeting the immunological risk-assessment machinery.