The overall lower percentages (compared to the high confirmation rates of IgG+IgM or solitary IgG+BIOSYNEX results,Figure 3) are partly due to the fact that an IgG ELISA was used also to confirm results with a solitary IgM band

The overall lower percentages (compared to the high confirmation rates of IgG+IgM or solitary IgG+BIOSYNEX results,Figure 3) are partly due to the fact that an IgG ELISA was used also to confirm results with a solitary IgM band. activity was considerably more stable than S1 and NCP IgG titres, and both reach a plateau after approximately 100 d. The sVNT proved to be not only highly specific, but also more sensitive than the specificity-focussed two-tiered serology approach. == Conclusions == Our results demonstrate the high specificity of two-tiered serology testing and highlight the sVNT used as a valuable tool to support Rasagiline mesylate modelling of SARS-CoV-2 transmission dynamics, Rasagiline mesylate complement molecular testing and provide relevant information to individuals. Keywords:SARS-CoV-2, serology, lateral flow assay, ELISA, longevity, neutralizing antibodies == Introduction == The novel coronavirus SARS-CoV-2 is the causative agent of the worldwide pandemic of coronavirus disease 2019 (COVID-19), which has led to millions of infections with substantial morbidity and mortality [1]. COVID-19 is characterized by a range of symptoms including cough, fever, pneumonia and a characteristic loss of smell and taste [2,3]. The clinical manifestations of COVID-19 differ considerably and range from asymptomatic or mild self-limiting disease to severe disease and death. Next to co-morbidities predisposing to severe disease, immune hyperresponsiveness appears to be a critical factor driving COVID-19 disease severity [4,5]. In the Netherlands, the spread of SARS-CoV-2 started in the Southern provinces, likely exacerbated by regional carnival celebrations following travel to and from Northern Italy during the school holidays [6,7]. However, due to limited capacity at the time, RT-PCR testing for SARS-CoV-2 was largely restricted to hospitalized patients with suspected COVID-19 and symptomatic individuals with moderate disease that had a recent travel history to high-risk areas, such as Northern Italy. Even household members of RT-PCR positive individuals were advised to self-isolate but not tested. Therefore, a large number of symptomatic individuals in The Netherlands were not tested for SARS-CoV-2 up until the start of July 2020, which left many affected individuals uncertain about whether or not their symptoms Rasagiline mesylate were due to COVID-19. Serological testing offers a possibility to abolish this uncertainty. In an early study, it was shown that seroconversion for anti-SARS-CoV-2 IgG and IgM occurred simultaneously or sequentially within 19 d of infection in all symptomatic COVID-19 patients analysed [8]. The receptor-binding domain (RBD) of the spike protein of coronaviruses (CoV) is a particularly interesting target for serological testing since it is the target of neutralizing antibodies [911], and serology tests based on the detection of these antibodies are being evaluated as indicators of protective immunity. A crucial requirement when offering individualized serological testing, however, is a very high specificity of the test(s) selected to avoid false positives. At the early stage of Rasagiline mesylate the pandemic, the risk and benefit of serological tests and in particular rapid tests, such as lateral flow assays (LFAs) were heavily debated [12]. Next to concerns about the performance of such rapid tests, another worry was poor registration and potential misinterpretation of the results of these tests outside controlled laboratory settings [13]. Following careful verification of a range of CE-marked serological test, Innatoss started in April 2020 to offer testing for SARS-CoV-2 antibodies in a mobile lab setting using finger-prick blood. LFA results were interpreted by trained staff and applied in the context of a two-tiered testing strategy to maximize specificity. This testing strategy combined an RBD-directed LFA with strong performance characteristics [14] with a highly specific anti-SARS-CoV-2 nucleocapsid protein (NCP) PTP-SL IgG ELISA for confirmation in follow-up serum samples. This dual test approach is Rasagiline mesylate in line with the recommended common practice for serologic testing of Lyme Borreliosis, which also serves to enhance specificity [15]. Pre-screening with an LFA reduces pressure on the general health care system since it abolishes the need for venous blood collection, which is then only necessary for LFA positive individuals for confirmatory ELISA. Here, we report the verification, performance and outcomes of this two-tiered serological testing strategy applied inn= 7241 individuals from mid-April to mid-August 2020 in The Netherlands. The majority of these individuals had experienced symptoms consistent with COVID-19 at least 4 weeks prior to testing. Our results demonstrate the high specificity and feasibility of this testing approach even in times of strict anti-COVID-19 lock-down measures. We further described the kinetics of anti-SARS-CoV-2 NCP and spike protein domain 1 (S1) IgG levels as well neutralizing antibodies measured using a surrogate virus neutralization test (sVNT) [16] in a subgroup of individuals that underwent diagnostic follow-up up to 20 weeks.