Prevalence of SARS-CoV-2 in Spain (ENE-COVID): a nationwide, population-based seroepidemiological study. Issue 10250 (22nd August 2020)

• Record Type: Journal Article
• Authors: Pollán, Marina; Pérez-Gómez, Beatriz; Pastor-Barriuso, Roberto; Oteo, Jesús; Hernán, Miguel A; Pérez-Olmeda, Mayte; Sanmartín, Jose L; Fernández-García, Aurora; Cruz, Israel; Fernández de Larrea, Nerea; Molina, Marta; Rodríguez-Cabrera, Francisco; Martín, Mariano; Merino-Amador, Paloma; León Paniagua, Jose; Muñoz-Montalvo, Juan F; Blanco, Faustino; Yotti, Raquel; Blanco, Faustino; Gutiérrez Fernández, Rodrigo; Martín, Mariano; Mezcua Navarro, Saturnino; Molina, Marta; Muñoz-Montalvo, Juan F.; Salinero Hernández, Matías; Sanmartín, Jose L.; Cuenca-Estrella, Manuel; Yotti, Raquel; León Paniagua, José; Fernández de Larrea, Nerea; Fernández-Navarro, Pablo; Pastor-Barriuso, Roberto; Pérez-Gómez, Beatriz; Pollán, Marina; Avellón, Ana; Fedele, Giovanni; Fernández-García, Aurora; Oteo Iglesias, Jesús; Pérez Olmeda, María Teresa; Cruz, Israel; Fernandez Martinez, Maria Elena; Rodríguez-Cabrera, Francisco D.; Hernán, Miguel A.; Padrones Fernández, Susana; Rumbao Aguirre, José Manuel; Navarro Marí, José M.; Palop Borrás, Begoña; Pérez Jiménez, Ana Belén; Rodríguez-Iglesias, Manuel; Calvo Gascón, Ana María; Lou Alcaine, María Luz; Donate Suárez, Ignacio; Suárez Álvarez, Oscar; Rodríguez Pérez, Mercedes; Cases Sanchís, Margarita; Villafáfila Gomila, Carlos Javier; Carbo Saladrigas, Lluis; Hurtado Fernández, Adoración; Oliver, Antonio; Castro Feliciano, Elías; González Quintana, María Noemí; Barrasa Fernández, José María; Hernández Betancor, María Araceli; Hernández Febles, Melisa; Martín Martín, Leopoldo; López López, Luis-Mariano; Ugarte Miota, Teresa; De Benito Población, Inés; Celada Pérez, María Sagrario; Vallés Fernández, María Natalia; Maté Enríquez, Tomás; Villa Arranz, Miguel; Domínguez-Gil González, Marta; Fernández-Natal, Isabel; Megías Lobón, Gregoria; Muñoz Bellido, Juan Luis; Ciruela, Pilar; Mas i Casals, Ariadna; Doladé Botías, Maria; Marcos Maeso, M. Angeles; Pérez del Campo, Dúnia; Félix de Castro, Antonio; Limón Ramírez, Ramón; Elías Retamosa, Maria Francisca; Rubio González, Manuela; Blanco Lobeiras, María Sinda; Fuentes Losada, Alberto; Aguilera, Antonio; Bou, German; Caro, Yolanda; Marauri, Noemí; Soria Blanco, Luis Miguel; del Cura González, Isabel; Hernández Pascual, Montserrat; Alonso Fernández, Roberto; Merino-Amador, Paloma; Cabrera Castro, Natalia; Tomás Lizcano, Aurora; Ramírez Almagro, Cristóbal; Segovia Hernández, Manuel; Ascunce Elizaga, Nieves; Ederra Sanz, María; Ezpeleta Baquedano, Carmen; Bustinduy Bascaran, Ana; Iglesias Tamayo, Susana; Elorduy Otazua, Luis; Benarroch Benarroch, Rebeca; Lopera Flores, Jesús; Vázquez de la Villa, Antonia;
• Is Part Of: Lancet. Volume 396:Issue 10250(2020)
• Page Start: 535
• Page End: 544
• Publication Date: 2020-08-22
• Subjects: Medicine -- Periodicals; Medicine -- Periodicals; Medicine; Medicine; Electronic journals; Periodicals; 610.5
• DOI: 10.1016/S0140-6736(20)31483-5
• Languages: English
• ISSNs: 0140-6736

Abstract

Summary: Background: Spain is one of the European countries most affected by the COVID-19 pandemic. Serological surveys are a valuable tool to assess the extent of the epidemic, given the existence of asymptomatic cases and little access to diagnostic tests. This nationwide population-based study aims to estimate the seroprevalence of SARS-CoV-2 infection in Spain at national and regional level. Methods: 35 883 households were selected from municipal rolls using two-stage random sampling stratified by province and municipality size, with all residents invited to participate. From April 27 to May 11, 2020, 61 075 participants (75·1% of all contacted individuals within selected households) answered a questionnaire on history of symptoms compatible with COVID-19 and risk factors, received a point-of-care antibody test, and, if agreed, donated a blood sample for additional testing with a chemiluminescent microparticle immunoassay. Prevalences of IgG antibodies were adjusted using sampling weights and post-stratification to allow for differences in non-response rates based on age group, sex, and census-tract income. Using results for both tests, we calculated a seroprevalence range maximising either specificity (positive for both tests) or sensitivity (positive for either test). Findings: Seroprevalence was 5·0% (95% CI 4·7–5·4) by the point-of-care test and 4·6% (4·3–5·0) by immunoassay, with a specificity–sensitivity range of 3·7% (3·3–4·0; both tests positive) to 6·2% (5·8–6·6; either test positive), with no differences by sex and lower seroprevalence in children younger than 10 years (<3·1% by the point-of-care test). There was substantial geographical variability, with higher prevalence around Madrid (>10%) and lower in coastal areas (<3%). Seroprevalence among 195 participants with positive PCR more than 14 days before the study visit ranged from 87·6% (81·1–92·1; both tests positive) to 91·8% (86·3–95·3; either test positive). In 7273 individuals with anosmia or at least three symptoms, seroprevalence ranged from 15·3% (13·8–16·8) to 19·3% (17·7–21·0). Around a third of seropositive participants were asymptomatic, ranging from 21·9% (19·1–24·9) to 35·8% (33·1–38·5). Only 19·5% (16·3–23·2) of symptomatic participants who were seropositive by both the point-of-care test and immunoassay reported a previous PCR test. Interpretation: The majority of the Spanish population is seronegative to SARS-CoV-2 infection, even in hotspot areas. Most PCR-confirmed cases have detectable antibodies, but a substantial proportion of people with symptoms compatible with COVID-19 did not have a PCR test and at least a third of infections determined by serology were asymptomatic. These results emphasise the need for maintaining public health measures to avoid a new epidemic wave. Funding: Spanish Ministry of Health, Institute of Health Carlos III, and Spanish National Health System.