{"doi":"10.1101/2020.10.05.20206664","title":"Antibody reactivity against SARS-CoV-2 in adults from the Vancouver metropolitan area, Canada","abstract":"BACKGROUND: Pre-existing antibody reactivity against SARS-CoV-2 in unexposed people is a potentially important consideration for COVID-19 severity and vaccine responses. However, it has been difficult to quantify due to a lack of reliable defined background titers in unexposed individuals. METHODS: We measured IgG against multiple SARS-CoV-2 antigens, SARS-CoV and other circulating coronavirus spike proteins using a highly sensitive multiplex assay, and total SARS-CoV-2 spike-specific antibodies (IgG/M/A) using a commercial CLIA assay in 276 adults from the Vancouver area, Canada between May 17th and June 19th 2020. Reactivity threshold in unexposed individuals were defined comparing to pre-pandemic sera and to sera from infants under 6 months of age. RESULTS: The seroprevalence from a SARS-CoV-2 exposure, adjusted for false-positive and false-negative test results, was 0.60% in our adult cohort. High antibody reactivity to circulating endemic coronaviruses was observed in all adults and was about 10-fold lower in infants under 6 months. Consistent with a waning of maternal antibodies, reactivity in infants decreased more than 50-fold eight months later. SARS-CoV-2 Spike, RBD, NTD or nucleocapsid antibody reactivity >100-fold above that of older infants was detected in the vast majority of unexposed adults and pre-pandemic sera. This antibody reactivity correlated with titers against circulating coronaviruses, but not with age, sex, or whether adults were healthcare workers. CONCLUSION: A majority of unexposed adults have pre-existing antibody reactivity against SARS-CoV-2. The lack of similar antibody reactivity in infants where maternal antibodies have waned suggests that this cross-reactivity is acquired, likely from repeated exposures to circulating coronaviruses.","journal":"medRxiv","year":2020,"id":125446,"datarank":0.16479184330021646,"base_score":1.0986122886681096,"endowment":1.0986122886681096,"self_citation_contribution":0.16479184330021646,"citation_network_contribution":0.0,"self_endowment_contribution":0.16479184330021646,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":2,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9537,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":323766,"name":"Sarah O’Connell","orcid":"0000-0002-1645-0722","position":1,"is_corresponding":false},{"id":571496,"name":"Christina Michalski","orcid":"0000-0001-9093-5325","position":2,"is_corresponding":false},{"id":571497,"name":"Sarah Dada","orcid":"0000-0002-3445-2377","position":3,"is_corresponding":false},{"id":480600,"name":"Sandeep Narpala","orcid":"0000-0002-1447-2709","position":4,"is_corresponding":false},{"id":572053,"name":"Jean Gelinas","orcid":null,"position":5,"is_corresponding":false},{"id":571498,"name":"Disha Mehta","orcid":"0000-0002-0856-9512","position":6,"is_corresponding":false},{"id":571499,"name":"Claire Cheung","orcid":"0000-0003-0603-2938","position":7,"is_corresponding":false},{"id":572054,"name":"Manjula Basappa","orcid":null,"position":8,"is_corresponding":false},{"id":571500,"name":"Matthias Görges","orcid":"0000-0003-2193-178X","position":9,"is_corresponding":false},{"id":571501,"name":"Vilte Barakauskas","orcid":"0000-0002-6909-0513","position":10,"is_corresponding":false},{"id":571502,"name":"David A. Goldfarb","orcid":"0000-0003-0835-9504","position":11,"is_corresponding":false},{"id":277153,"name":"Daniel C. Douek","orcid":"0000-0001-5575-8634","position":12,"is_corresponding":false},{"id":218075,"name":"Adrian B. McDermott","orcid":"0000-0003-0616-9117","position":13,"is_corresponding":false},{"id":571503,"name":"Pascal M. Lavoie","orcid":"0000-0002-2205-0362","position":14,"is_corresponding":false},{"id":571495,"name":"Abdelilah Majdoubi","orcid":"0000-0002-2053-4793","position":0,"is_corresponding":true}],"reference_count":33,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-18T23:15:15.482227Z","pmid":"33052362","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}