Antibody response in patients admitted to the hospital with suspected SARS-CoV-2 infection: results from a multicenter study across Spain

Fuentes, Ana; Serrano-Conde, Esther; Roldán, Carolina; Benito-Ruesca, Rafael; Mejías, Gregoria; Sampedro, Antonio; March-Roselló, Gabriel; Fernández-Natal, Isabel; Esperalba, Juliana; Rodríguez, Mario José; Martínez de Aguirre, Paula; Salas, Carlos; Roc, María Lourdes; Soria, Luis Miguel; Parra-Grande, Mónica; Montero, María Dolores; Fernández-Roblas, Ricardo; Franco-Álvarez de Luna, Francisco; Lozano, Carmen; García, Federico

AIM: To evaluate the serological response against SARS-CoV-2 in a multicenter study representative of the Spanish COVID pandemic. METHODS: IgG and IgM + IgA responses were measured on 1466 samples from 1236 Spanish COVID-19 patients admitted to the hospital, two commercial ELISA kits (Vircell SL, Spain) based on the detection of antibodies against the viral spike protein and nucleoprotein, were used. RESULTS: Approximately half of the patients presented antibodies (56.8% were IgM + IgA positive and 43.0% were IgG positive) as soon as 2 days after the first positive PCR result. Serological test positivity increased with time from the PCR test, and 10 days after the first PCR result, 91.5% and 88.0% of the patients presented IgM + IgA and IgG antibodies, respectively. CONCLUSION: The high values of sensitivity attained in the present study from a relatively early period of time after hospitalization support the use of the evaluated serological assays as supplementary diagnostic tests for the clinical management of COVID-19.