A large outbreak of COVID-19 linked to an end of term trip to Menorca (Spain) by secondary school students in summer 2021

Abstract

Background: An outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) occurred in young people from Catalonia (Spain) who travelled to Menorca (Spain) in summer 2021. This outbreak appeared when governments relaxed Covid-19 preventive measures: the mask usage and the opening of nightlife. It was related to a super-disseminating mass event: Sant Joan festivities in Ciutadella. The aim of this article is to describe an outbreak of COVID-19 in young people aged 17–19 years from Catalonia travelling to Menorca. Methods: This is an observational study of a COVID-19 outbreak. The study population comprised Catalonian youth aged 17–19 years who travelled to Menorca from 15 June to 10 July. Epidemiological descriptive indicators were obtained. Descriptive and geographical statistics were carried out. Bivariate Moran’s I test was used to identify spatial autocorrelation between the place of residence and deprivation. The outbreak control method was based on identifying and stopping chains of transmission by implementing the test-trace-isolate-quarantine (TTIQ) strategy. Results: We identified 515 confirmed cases infected in Menorca, 296 (57.5%) in girls and 219 (42.5%) in boys, with a total of 2,280 close contacts. Of them, 245 (10.7%) were confirmed as cases. The cases were diagnosed between 15 June and 10 July. None of the persons with confirmed infection died or required hospitalisation. The attack rate was 27.2%. There was an inverse relationship between deprivation and number of confirmed cases (p<0.005), there were clusters of confirmed cases in the most socioeconomic favoured areas. Discussion: The outbreak is related with young people from socioeconomic favoured areas who travelled to Menorca in summer 2021. Failure to comply with preventive measures in binge-drinking events and during holidays may have favoured SARS-CoV-2 transmission. The interauthority coordination and establishment of a clear line of leadership allowed continuous communication between institutions, which were key to managing this complex COVID-19 outbreak.