Study Finds That 11% of Andorra’s Population Was Exposed to SARS-CoV-2 Virus During First Wave

ISGlobal, Actua Innovació and the Andorran Health Care Service (SAAS) have signed an agreement to improve infectious disease prediction and biosecurity in Andorra

Photo: Ordino Arcalís (Andorra), November 2019 /

During the first wave of the COVID-19 pandemic, 11% of the population of Andorra was exposed to the SARS-CoV-2 virus and seasonal workers were the most affected group, according to a seroprevalence study coordinated by the Andorran Health Care Service (SAAS) in collaboration with the Barcelona Institute for Global Health (ISGlobal)—a centre supported by the ”la Caixa” Foundation—and Actua Innovació. The study, recently published in The Lancet Regional Health – Europe, was conducted under the umbrella of a collaboration agreement between the three institutions to improve infectious disease prevention and biosecurity in Andorra.

SARS-CoV-2 Antibody Prevalence Study

In May 2020, 91% of the population of Andorra—a total of 70,624 people—participated in a study to estimate the prevalence of antibodies against SARS-CoV-2. The study found that 11% of Andorra’s population had antibodies against the virus during the first wave of the pandemic, showing that a considerable portion of the population was apparently exposed to SARS-CoV-2 during the initial peak. This percentage was more than twice as high as that found by the ENE-COVID study in Spain during the first wave (5%). This difference can largely be attributed to the pandemic’s arrival in Andorra during the winter season, when the country experiences a high-intensity influx of tourism, and to the fact that Andorra had strong diagnostic capacity as part of its COVID-19 management strategy.

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%).

“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. “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,” added Cristina Royo-Cebrecos, SAAS researcher and lead author of the study.

Improving Prediction of Other Infectious Diseases and Health Effects of Climate Change and Air Pollution in Andorra

The collaboration agreement undergirding the study calls for the three institutions to work together to develop epidemiological assessment plans, biosecurity reinforcement policies, correlational studies of epidemiological, environmental and demographic variables and the genetic tracing of both the population and micro-organisms with the potential to cause epidemics in Andorra.

“One of Andorra’s priorities is to develop digital health and predictive medicine projects,” explained Marc Pons, director of Actua Innovació. In the context of the pandemic, “these projects need to be extended to the biosecurity aspect,” he added. “Collaboration with ISGlobal is essential in this regard, as it provides us with the necessary excellence and scientific knowledge to address this important issue, which has such a large current and future impact.”

Antoni Plasència, director general of ISGlobal, underscored “the importance of this strategic alliance for epidemic prevention and preparedness”. He concluded: “As we have seen with the COVID-19 pandemic, in a global and hyperconnected world, we need new knowledge and innovative approaches to be ready to prevent and respond to cross-border health risks, which often begin as local phenomena but carry the risk of rapidly affecting the entire planet.”


Cristina Royo-Cebrecos et al. Mass SARS-CoV-2 serological screening, a population-based study in the Principality of Andorra. The Lancet Regional Health – Europe. May 2021.