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 of Andorra

Keywords: COVID-19; Andorra; Screening; SARS-CoV-2; Epidemiology; Diagnostics


– 11% of Andorra’s population had antibodies against the virus during the first wave of the pandemic.

– By age group, prevalence was highest in adults over 90 years of age (15.2%), followed by adults aged 80-89 years (13.8%), adolescents aged 10-19 years (13.7%) and adults aged 50-59 years (13.6%).

 – By population group, seroprevalence was higher in seasonal workers (13.3%)—those working in Andorra during ski season (October to May)—than in the general population (9.7%).

The study allowed us to identify infection hotspots and should contribute to the design of tailored interventions to prevent SARS-CoV-2 transmission in Andorra.

Cristina Royo-Cebrecos, SAAS researcher and lead author of the study

Description of the Study:

  • Title: Mass SARS-CoV-2 serological screening, a population-based study in the Principality of Andorra.
  • Principal Investigator: Cristina Royo-Cebrecos.
  • Co-Investigators: David Vilanova, Joel López, Vanesa Arroyo, Marc Pons, Guillem Francisco, Mireia G. Carrasco, Josep M. Piqué, Sergi Sanz, Carlota Dobaño and Alberto L. García-Basteiro.
  • Coordinating Centres: The study is coordinated by the Servei Andorrà d’Atenció Sanitària (SAAS) and has the collaboration of the Institut de Salut Global de Barcelona (ISGlobal).
  • Study Population: 91% of the population of the Principality of Andorra (70,624 inhabitants).
  • Design: Two cross-sectional serological surveys were conducted throughout Andorra from 4 to 28 May 2020. Seroprevalence of antibodies against SARS-CoV-2 was estimated and the main socio-demographic factors associated with being seropositive were analysed.
  • Methods: Serological surveys were performed using a rapid serological test (nCOV IgG/IgM) on a finger prick blood sample.

Objectives of the Study:

Principal Objective: To estimate SARS-CoV-2 seroprevalence throughout the Principality of Andorra by universal serological testing under a lockdown environment.

More about this Study:

Scientific Context: Andorra is a small country located in the Pyrenees attracting millions of visitors for tourism, mostly associated with skiing, and nature-related activities. As its neighbouring countries, Spain and France, it has been heavily affected by the COVID-19 pandemic. 

Added Value: “This is the first seroprevalence study to assess the entire population of a country with universal serological testing and the largest of its kind worldwide,” explained ISGlobal researcher Alberto García-Basteiro, last author of the paper.

Servei Andorrà d’Atenció Sanitària (SAAS): It is a parapublic entity which, by delegation from the Ministry of Health, is responsible for providing most health care and coordinating all the activities carried out in Andorra in the field of public care.

Some of thefundamental objectives of the SAAS are to promote the most efficient use of all available resources to improve the level of health of the population of the Principality of Andorra; to fulfil the provision of health services, whether individual or collective, for all the population residing or travelling in the Principality of Andorra, in the form and conditions legally established for each case; to establish the appropriate organisation to facilitate health care which includes preventive, curative and rehabilitative aspects, in a coordinated manner between the different levels of care; to integrate all the health resources for public use in a single administrative and functional body and to guarantee the quality of health care and control of expenditure.

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