Seroprevalence Study of the EAP Sardenya

Which is the community immunity against SARS-CoV-2? In this study of EAP Sardenya, it will be monitored the seroprevalence of antibodies against COVID-19 in probable and possible cases

Dr. Carles Brotons, director of the Research Unit of the EAP Sardenya and Dr. Jordi Serrano, founder and CEO of Universal Doctor explain us about the study of the use of rapid diagnostic tests of the COVID-19 in the Primary Care of Catalonia.

Keywords: General practice; infectious diseases; practice management; primary care; public health; screening


Images of some of the results obtained

Results for the EAP Sardenya COVID-19 seroprevalence study.
Prevalence by age groups in Spanish asymptomatic population (2020).
Results for the EAP Sardenya COVID-19 seroprevalence study.
Frequency of symptoms in positive cases in a Spanish symptomatic population (2020): overall and by sex.

Key Messages:

  1. Seroprevalence of SARS-CoV-2’s antibodies in possible cases is 5.5%.
  2. Seroprevalence of SARS-CoV-2’s antibodies in symptomatic patients is 40%.
  3. Thirteen percent of symptomatic patients were hospitalized and 2% died.

Description of the Study:

  • Title: Community Seroprevalence of COVID-19 in Probable and Possible Cases at Primary Health Care Centres in Spain.
  • Principal Investigator: Patricia Montenegro and Carlos Brotons.
  • Co-Investigators: Jordi Serrano, Diana Fernández, Carlos Garcia-Ramos, Begoña Ichazo, Jeannine Lemaire, Irene Moral, Ricky Pérez Wienese, Marc Pitarch, Mireia Puig, M Teresa Vilella, Jaume Sellarès.
  • Center of Implementation: EAP Sardenya.
  • Study Population:
    For the seroprevalence study, we selected a simple random sampling of 600 individuals 1 year or older from a total population of 19 899 individuals registered at a primary health care center from a community area of Barcelona, Spain. Besides, institutionalized patients, terminally ill patients, and suspected cases of COVID-19 were excluded because they were confined either at home or at the community residences. Also, patients who tested positive for COVID-19 prior to recruitment were excluded.
    And, for the follow-up study, we included all patients aged 1 year or older consulting the primary care physician either face-to-face or by phone with mild or moderate symptoms (without a confirmed diagnosis) during the COVID-19 pandemic from 2 March to 24 April 2020.
  • Design: The seroprevalence study in asymptomatic patients used a cross-sectional survey approach to recruit individuals for participation in the study (Study population A). The follow-up study used an observational prospective follow-up approach for monitoring suspected cases of COVID-19 followed by primary care physicians (Study population B).
  • Methods: COVID-19 rapid lateral flow immunoassays.

Objectives of the Study:

Principal Objective: This study aims to estimate the seroprevalence of antibodies against SARS-CoV-2 in possible cases (without symptoms) in a community setting and to outline the antibody profiles in probable cases (with mild or moderate symptoms) that were followed up by GPs since the beginning of the pandemic.

Secondary Objective: As a secondary objective, we estimated the proportions of symptomatic patients seen at an emergency department (ED), hospitalized or dying, and identified the most important clinical symptoms associated with a positive infection.

More about this Study:

Scientific Context: There is a scarcity of information about patients with mild or moderate symptoms during the coronavirus disease 2019 (COVID-19). This is especially true for those who attended and were followed up at primary care settings.

EAP Sardenya: It is a health center open to society with the mission of offering high-quality services to the patient, using the most innovative technology. It aims to take responsibility for the Primary Care of the population integrated in its Basic Health Area (ABS). Since the start of the pandemic, the EAP Sardenya has been actively involved in many COVID-19 related projects such as this seroprevalence study.

EAP Sardenya leads this COVID-19 seroprevalence study.

Other Studies about Serology:

Effectiveness of vaccine combination

Científicos franceses demuestran que la vacunación primaria con dos vacunas diferentes sería más eficaz que la vacunación con dos vacunas idénticas.

COVID-19 immunity in healthcare professionals

Determining whether there is protection against reinfection is important for controlling healthcare workers implications during the pandemic due to their continous professional contact with COVID-19…

COnV-ert study, convalescent plasma to stop COVID-19

Early administration of convalescent plasma in people over 50 years of age with mild to moderate COVID-19 disease may slow disease progression and decrease the…

Mass SARS-CoV-2 Serological Screening in Andorra

This study aims to estimate the prevalence of antibodies against SARS-CoV-2 and help improve the prediction of infectious diseases and increase biosecurity in the Principality…


SAPRIS-SERO is a study to estimate the seroprevalence of SARS-CoV-2 infection in the epidemiological cohorts Constances, E3-E4N, NutriNet-Santé and Elfe-Epipage2 in France.


Identifying true markers of protective immunity will allow for the identification of individuals, in particular healthcare personnel working with COVID-19 patients and in other critical…


The COVICAT study aims to evaluate the evolution of the incidence of SARS-CoV-2 coronavirus infection in the Catalan population over a 12-month period.

Convalescent plasma therapy and COVID-19

Convalescent plasma with anti-SARS-CoV-2 antibodies appears to be a very promising approach in the context of protracted COVID-19 symptoms in patients unable to mount a…

COVonco Study

Join the COVonco study and help understand the impact of COVID-19 in oncology.


The EpiCOV project aims to provide a global and scientifically reliable mapping of the immune status of the population in France through serological tests and…