PLoS ONE (Jan 2021)

"Mass gathering events and COVID-19 transmission in Borriana (Spain): A retrospective cohort study".

  • Salvador Domènech-Montoliu,
  • Maria Rosario Pac-Sa,
  • Paula Vidal-Utrillas,
  • Marta Latorre-Poveda,
  • Alba Del Rio-González,
  • Sara Ferrando-Rubert,
  • Gema Ferrer-Abad,
  • Manuel Sánchez-Urbano,
  • Laura Aparisi-Esteve,
  • Gema Badenes-Marques,
  • Belén Cervera-Ferrer,
  • Ursula Clerig-Arnau,
  • Claudia Dols-Bernad,
  • Maria Fontal-Carcel,
  • Lorna Gomez-Lanas,
  • David Jovani-Sales,
  • Maria Carmen León-Domingo,
  • Maria Dolores Llopico-Vilanova,
  • Mercedes Moros-Blasco,
  • Cristina Notari-Rodríguez,
  • Raquel Ruíz-Puig,
  • Sonia Valls-López,
  • Alberto Arnedo-Pena

DOI
https://doi.org/10.1371/journal.pone.0256747
Journal volume & issue
Vol. 16, no. 8
p. e0256747

Abstract

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ObjectiveMass gathering events (MGEs) are associated with the transmission of COVID-19. Between 6 and 10 March 2020, several MGEs related to the Falles festival took place in Borriana, a municipality in the province of Castellon (Spain). The aim of this study was to estimate the incidence of COVID-19 and its association with these MGEs, and to quantify the potential risk factors of its occurrence.MethodsDuring May and June 2020, a population-based retrospective cohort study was carried out by the Public Health Center of Castelló and the Hospital de la Plana in Vila-real. Participants were obtained from a representative sample of 1663 people with potential exposure at six MGEs. A questionnaire survey was carried out to obtain information about attendance at MGEs and COVID-19 disease. In addition, a serologic survey of antibodies against SARS-Cov-2 was implemented. Inverse probability weighted regression was used in the statistical analysis.ResultsA total of 1338 subjects participated in the questionnaire survey (80.5%), 997 of whom undertook the serologic survey. Five hundred and seventy cases were observed with an attack rate (AR) of 42.6%; average age was 36 years, 62.3% were female, 536 cases were confirmed by laboratory tests, and 514 cases were found with SARS-CoV-2 total antibodies. Considering MGE exposure, AR was 39.2% (496/1264). A dose-response relationship was found between MGE attendance and the disease, (adjusted relative risk [aRR] = 4.11 95% confidence interval [CI]3.25-5.19). Two MGEs with a dinner and dance in the same building had higher risks. Associated risk factors with the incidence were older age, obesity, and upper and middle class versus lower class; current smoking was protective.ConclusionsThe study suggests the significance of MGEs in the COVID-19 transmission that could explain the subsequent outbreak in Borriana.