The Conundrum of Giglio Island: Unraveling the dynamics of an apparent resistance to COVID-19 – A descriptive study Academic Article uri icon

  • Overview
  • Research
  • Identity
  • Additional Document Info
  • View All


  • Objectives: Despite an extensive risk of exposure to COVID-19, the residents of Giglio Island, Italy, did not develop any symptom of SARS-CoV-2. The present study aims to characterize the nature of exposure and to describe the local population dynamics underlying its apparent resistance to COVID-19. Methods: Descriptive study of an islander partially-segregated population cohort based on a seroprevalence screening conducted from Aprile 29 to May 3, 2020 and including SARS-CoV-2 seroprevalence and viral prevalence in samples of saliva assessed through RT-qPCR. Serologic testing was performed using a COVID-19 IgG/IgM rapid test while molecular analyses were carried out by Allplex 2019-nCoV Assay (Seegene). Results: A total of 634 residents out of 748 (84.8%) present at the time, and 89 non-residents underwent serological testing. 364 males and 359 females with a median age of 58.5 years. The serological screening identified one positive, asymptomatic subject. The Nucleic Acid Amplification Tests (NAAT) did not yield any positive result. Conclusion: Despite extensive exposure to SARS-CoV-2, possibly only one new asymptomatic infection occurred in this population, as documented by IgM positivity not confirmed by RT-qPCR. This may be due to unknown protective factors or chance. On the basis of this baseline study, using its population as a reference model, further investigations will be conducted to test the advanced hypotheses, focusing on the evaluation of a possible cross-reactivity to SARS-CoV-2 from exposure to endemic viruses.


  • Bognanni, Antonio
  • Schiaffino, Armando
  • Pimpinelli, Fulvia
  • Donzelli, Sara
  • Celesti, Ilaria
  • Strano, Sabrina
  • Solari, Elena
  • Schiaffino, Giorgia
  • Solari, Gabriele
  • Solari, Domenico
  • Delbue, Serena
  • Rigoni, Marta
  • Nollo, Giandomenico
  • Muti, Greta E
  • Muti Schünemann, Giovanna EU
  • Schunemann, Holger
  • Blandino, Giovanni
  • Morrone, Aldo
  • Muti, Paola

publication date

  • 2021