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A Population-Based Seroepidemiological Study of SARS-CoV-2 in Spain (ENE-COVID)

20 Pages Posted: 14 Jul 2020

See all articles by Marina Pollan

Marina Pollan

Carlos III Institute of Health - National Center for Epidemiology

Beatriz Perez-Gomez

Carlos III Institute of Health

Roberto Pastor-Barriuso

Carlos III Institute of Health - National Center for Epidemiology

Jesús Oteo

Carlos III Institute of Health - National Centre for Microbiology

Miguel A. Hernán

Harvard University - Departments of Epidemiology and Biostatistics

Mayte Pérez-Olmeda

Carlos III Institute of Health - National Centre for Microbiology

Jose L. Sanmartín

Government of the Kingdom of Spain - Ministry of Health

Aurora Fernández-García

Carlos III Institute of Health - National Centre for Microbiology

Israel Cruz

Carlos III Institute of Health

Nerea Fernández de Larrea

Carlos III Institute of Health - National Center for Epidemiology

Marta Molina

Government of the Kingdom of Spain - Ministry of Health

Francisco Rodríguez-Cabrera

Carlos III Institute of Health

Mariano Martín

Government of the Kingdom of Spain - Ministry of Health

Paloma Merino-Amador

Universidad Complutense de Madrid (UCM) - Clinical Hospital San Carlos

Jose León Paniagua

Carlos III Institute of Health

Juan F. Muñoz-Montalvo

Government of the Kingdom of Spain - Ministry of Health

Faustino Blanco

Government of the Kingdom of Spain - Ministry of Health

Raquel Yotti

Carlos III Institute of Health

ENE-COVID Study Group

More...

Abstract

Background: Spain is one of the European countries most affected by COVID-19 pandemic. Serological surveys are a valuable tool to assess the extent of the epidemic, given the existence of asymptomatic cases and the limited access to diagnostic tests. This nation-wide population-based study aims to estimate the seroprevalence of SARS-CoV-2 infection in Spain at national and regional level (province).

Methods: Residents in 35,893 households were selected from municipal rolls using two-stage random sampling stratified by province and municipality size. Participants (74·9% of contacted individuals) answered a questionnaire, received a Point-of-Care (POC) antibody test and, if agreed, donated a blood sample for additional testing with a chemiluminescent microparticle immunoassay. Prevalences (IgG antibodies) were adjusted using sampling weights and post-stratification to allow for differences in nonresponse rates based on age, sex, and census-tract income. Using results for both tests, we propose a prevalence range maximizing either specificity (positivity for both tests) or sensitivity (positive for either test) (Sp-Sn-range).

Findings: Seroprevalence among the 60,979 participants was 5% (POC) and 4.6% (immunoassay) (Sp-Sn-range 3·7% to 6·2%), with no differences by sex or age except lower figures in children. There was substantial geographical variability, with higher prevalences around Madrid (>10%) and lower in coastal areas (<2%). Seroprevalence among participants with a past positive PCR was 89% (Sp-Sn-range 87% to 91%), and, in those with ≥3 symptoms 17% (Sp-Sn-range 15% to 20%). Around 33% of participants with a positive result were asymptomatic (Sp-Sn-range 21% to 36%).

Interpretation: The majority of the Spanish population is seronegative to SARS-CoV-2 infection, even in hot-spot areas. Most PCR-confirmed cases have detectable antibodies, but a substantial proportion of people with symptoms compatible with COVID19 did not have a PCR and one third of infections determined by serology were asymptomatic. These results emphasize the need of maintaining public health measures to avoid a new epidemic wave.

Funding Statement: Spanish Ministry of Health, Institute of Health Carlos III & Spanish National Health System.

Declaration of Interests: The authors declare no competing interests.

Ethics Approval Statement: The Institutional Review Board of the Institute of Health Carlos III approved the study (Register number: PI 39_2020). The Spanish Agency for Personal Protection was consulted. Written informed consent was obtained from all study participants.

Suggested Citation

Pollan, Marina and Perez-Gomez, Beatriz and Pastor-Barriuso, Roberto and Oteo, Jesús and Hernán, Miguel A. and Pérez-Olmeda, Mayte and Sanmartín, Jose L. and Fernández-García, Aurora and Cruz, Israel and Fernández de Larrea, Nerea and Molina, Marta and Rodríguez-Cabrera, Francisco and Martín, Mariano and Merino-Amador, Paloma and Paniagua, Jose León and Muñoz-Montalvo, Juan F. and Blanco, Faustino and Yotti, Raquel and Study Group, ENE-COVID, A Population-Based Seroepidemiological Study of SARS-CoV-2 in Spain (ENE-COVID) (5/28/2020). Available at SSRN: https://ssrn.com/abstract=3616010 or http://dx.doi.org/10.2139/ssrn.3616010

Marina Pollan (Contact Author)

Carlos III Institute of Health - National Center for Epidemiology ( email )

c/ Monforte de Lemos 5
Madrid, 28029
Spain

Beatriz Perez-Gomez

Carlos III Institute of Health ( email )

c/ Monforte de Lemos 5
Madrid, Madrid 28029
Spain

Roberto Pastor-Barriuso

Carlos III Institute of Health - National Center for Epidemiology

c/ Monforte de Lemos 5
Madrid, 28029
Spain

Jesús Oteo

Carlos III Institute of Health - National Centre for Microbiology

Monforte de Lemos 5
Madrid, Madrid 28029
Spain

Miguel A. Hernán

Harvard University - Departments of Epidemiology and Biostatistics

Boston, MA 02115
United States

Mayte Pérez-Olmeda

Carlos III Institute of Health - National Centre for Microbiology

Monforte de Lemos 5
Madrid, Madrid 28029
Spain

Jose L. Sanmartín

Government of the Kingdom of Spain - Ministry of Health

Spain

Aurora Fernández-García

Carlos III Institute of Health - National Centre for Microbiology

Monforte de Lemos 5
Madrid, Madrid 28029
Spain

Israel Cruz

Carlos III Institute of Health

c/ Monforte de Lemos 5
Madrid, Madrid 28029
Spain

Nerea Fernández de Larrea

Carlos III Institute of Health - National Center for Epidemiology

c/ Monforte de Lemos 5
Madrid, 28029
Spain

Marta Molina

Government of the Kingdom of Spain - Ministry of Health

Spain

Francisco Rodríguez-Cabrera

Carlos III Institute of Health

c/ Monforte de Lemos 5
Madrid, Madrid 28029
Spain

Mariano Martín

Government of the Kingdom of Spain - Ministry of Health

Spain

Paloma Merino-Amador

Universidad Complutense de Madrid (UCM) - Clinical Hospital San Carlos

Calle del Prof Martín Lagos
Madrid, 28040
Spain

Jose León Paniagua

Carlos III Institute of Health

c/ Monforte de Lemos 5
Madrid, Madrid 28029
Spain

Juan F. Muñoz-Montalvo

Government of the Kingdom of Spain - Ministry of Health

Spain

Faustino Blanco

Government of the Kingdom of Spain - Ministry of Health

Spain

Raquel Yotti

Carlos III Institute of Health

c/ Monforte de Lemos 5
Madrid, Madrid 28029
Spain

No contact information is available for ENE-COVID Study Group

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