RESUMO
Monitoring the burden and spread of infection with the new coronavirus SARS-CoV-2, whether within small communities or in large geographical settings, is of paramount importance for public health purposes. Serology, which detects the host antibody response to the infection, is the most appropriate tool for this task, since virus-derived markers are most reliably detected during the acute phase of infection. Here we show that our ELISA protocol, which is based on antibody binding to the Receptor Binding Domain (RBD) of the S1 subunit of the viral Spike protein expressed as a novel fusion protein, detects antibody responses to SARS-CoV-2 infection and COVID-19 vaccination. We also show that our ELISA is accurate and versatile. It compares favorably with commercial assays widely used in clinical practice to determine exposure to SARS-CoV-2. Moreover, our protocol accommodates use of various blood- and non-blood-derived biospecimens, such as breast milk, as well as dried blood obtained with microsampling cartridges that are appropriate for remote collection. As a result, our RBD-based ELISA protocols are well suited for seroepidemiology and other large-scale studies requiring parsimonious sample collection outside of healthcare settings.
RESUMO
BackgroundSARS-CoV-2, the virus that causes COVID-19, has rapidly spread globally beginning in late 2019. Early areas impacted by this pandemic in the US include Essex County, New Jersey. Beyond understanding the prevalence of active infections and deaths, it is important to understand the true burden of infection in the community, as indicated by seroprevalence of antibodies directed to the virus. Understanding the spectrum of disease is key to the effectiveness of primary prevention and control measures and the design of interventions against transmission of infection. MethodsWe utilized venue-based-sampling (VBS), implemented by a community partner, to sample members of the community in Essex County. In VBS the venues are randomized as a proxy for randomizing the attendees of the venues. We asked standard demographic questions, questions about symptoms and PCR testing and previous antibody testing. Participants provide a blood sample collected by finger stick with the Neoteryx Mitra Collection device. Samples were tested using a novel ELISA based approached developed by our team. ResultsFrom September 15, 2020 to December 22, 2020, we conducted 92 randomly selected sampling events where we approached 1349 individuals for screening. Of these, 924 consented and had complete data for analysis. Only 6.5% of the sample reported any COVID-19 like symptoms while 45.9% had sought out a COVID-19 test. In total 13 (1.4%) participants received a positive SARS-CoV-2 PCR test result. While 33 participants (2.6%) sought a SARS-CoV-2 antibody test, only 0.5% of the sample reported a positive antibody result. Testing in this study identified 83 (9.0%) participants positive for SARS-CoV-2 antibodies. ConclusionWe recruited a large sample of the population of Essex County, New Jersey using VBS, electronic surveys, novel sample collection and lab methods. Our findings suggest that the burden of SARS-Cov-2 is slightly more than six times than that suggested by PCR testing. This burden is higher than most estimates obtained through studies of remnant blood samples from hospitals (4.2%), samples from staff at a public-school system (2.9%), and residents of a California county recruited with targeted Facebook ads (1.5%). (9-11) Moreover, with only 6.5% of the sample reporting any COVID-19-like symptoms, our finding suggests that the number of asymptomatic persons may be close to 1.5 times greater than anyone reporting symptoms.
