LAUSR

The ongoing pandemic of COVID-19, caused by the novel coronavirus SARS-CoV-2, is a matter of global concern. As of late July 2020, the total number of confirmed COVID-19 cases worldwide has surged past 14 million, causing more than 600,000 deaths [1]. To impede its rapid spread, much of the world have resorted to partial or complete lockdown, resulting in an enormous social and economic impact. In the absence of any functioning vaccine or treatment, rapid and accurate detection of COVID-19 infections is crucial for limiting the associated disease burden. Currently, reverse transcriptase real-time polymerase chain reaction (RT-PCR) based test of nasal and throat swabs is the gold standard for identifying COVID-19 infected patients. However, due to insufficient viral load at the time of testing [2], RT-PCR cannot detect previous exposure to SARS-CoV-2, which is important to evaluate the prevalence of infections in the population for devising measures to control virus transmission. In such cases, serological assays, which detect SARS-CoV-2-specific antibodies in blood samples of patients, could play a significant role by facilitating the identification of previous exposure to SARS-CoV-2. Serological assays can also assist in detecting a large number of subclinical infections in the community arising largely due to the high proportion of asymptomatic COVID-19 cases, and in identifying donors with highly reactive antibodies for convalescent plasma therapy. However, most of the SARS-CoV-2-specific serological assays reported so far in the literature employ recombinant proteins [3], which have several limitations. These include high storage constraints, batch-to-batch variations affecting reproducibility, and most importantly low sensitivity and specificity due to the presence of cross-reactive antibodies arising from previous exposure to genetically similar human coronaviruses [4] (seasonal coronaviruses as well as SARS-CoV, the causative agent of the 2003 SARS outbreak). Thus, there is an imminent need to develop improved serological assays for combating the ongoing COVID-19 pandemic. In the current issue of EBioMedicine, Ng and colleagues attempt to address the above limitations of current serological