The Conundrum of Giglio Island: unraveling the dynamics of an apparent resistance to COVID-19 – A descriptive study
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Abstract
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
We conducted seroprevalence screening from April 29 to May 3, 2020 across the three main settlements on the island. We invited the adult resident population, present on the island to undergo testing by rapid serologic assay and to provide a sample of saliva for molecular validation. We monitored the participation through the official municipality residents’ list. 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 did not yield any positive result.
Conclusion
Despite extensive exposure to SARS-CoV-2, only one new asymptomatic infection occurred in this population. This may be due to unknown protective factors or chance. On the basis of this first descriptive study, using its population as a reference model, further investigations will be conducted to characterize the summer period exposure and to test the advanced hypotheses, focusing on the evaluation of a possible cross-reactivity to SARS-CoV-2 from exposure to endemic viruses.
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SciScore for 10.1101/2021.01.08.20248948: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IRB: This study received ethical approval on April 25, 2020 by the Ethical Committee of the “Istituto Nazionale Malattie
Consent: Subjects signed an informed consent.Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
Antibodies Sentences Resources This rapid kit is a Lateral-Flow, solid-phase Immunochromatographic Assay (LFIA) for the rapid, qualitative and differential detection of IgG and IgM antibodies. IgMsuggested: NoneResults from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Re…SciScore for 10.1101/2021.01.08.20248948: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IRB: This study received ethical approval on April 25, 2020 by the Ethical Committee of the “Istituto Nazionale Malattie
Consent: Subjects signed an informed consent.Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
Antibodies Sentences Resources This rapid kit is a Lateral-Flow, solid-phase Immunochromatographic Assay (LFIA) for the rapid, qualitative and differential detection of IgG and IgM antibodies. IgMsuggested: NoneResults from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Strengths and limitations: There are several strengths to our study. The fact that the island population remained isolated throughout the lockdown period creates a closed cohort model with few confounding factors and a reasonably well characterized exposure. Also, the data and sample collection of our study has been properly standardized on the basis of predetermined criteria, as to increase reproducibility and limit bias. The high participation rate also reduces concerns of selection bias. There are also some limitations. A portion (15.2%) of the resident population did not participate to the serologic screening. This factor, associated to the inevitable lack of blinding among the islanders and the voluntary basis of participation, might have biased the results, underestimating the positive rate. The great variability in rapid serological test performances, particularly in regard of its sensitivity, might have led to overestimate the negative rate. The molecular tests, despite having a confirmatory role, given the time interval between the actual beginning of the study and the time of possible exposure, might have biased the results to finding no cases, failing to recognize a low viral count from the prior month’s infection. While the sample size is limited, it is naturally given by the island’s population. However, chance as a possible explanation of our findings cannot be excluded. Findings in comparison to other studies: There are few comparisons with other studies, becau...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
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