Clinical Severity in Different Waves of SARS-CoV-2 Infection in Sicily: A Model of Smith's "Law of Declining Virulence" from Real-World Data.

BACKGROUND: The COVID-19 epidemic had a rapid spread worldwide with a continuous and fast mutation of the virus, resulting in the emergence of several variants of concern (VOC). The aim of this study was to evaluate the severity of each VOC among SARS-CoV-2 infected subjects by investigating deaths, ICU admissions, intubations, and severe critical symptoms. METHODS: An ecological observational study was performed to evaluate mortality rates and clinical characteristics of 321,490 unvaccinated Sicilian SARS-CoV-2 cases observed from 2 March 2020 to 27 March 2022. Odds ratios (OR) and 95% confidence intervals (CI) were calculated by multivariate logistic regression analysis evaluating factors determining a clinical worsening. RESULTS: Delta (adj-OR 3.00, 95% Cls 2.70-3.33) and wild-type (adj-OR 2.41, 95% Cls 2.2-2.62) variants had a higher risk than the Omicron strain for developing critical COVID-19 necessitating intubation and eventually undergoing death. Moreover, males appeared to be significantly more susceptible to developing the worst clinical outcome considered, as did older subjects. CONCLUSIONS: The present study provides evidence of factors implicated in the worsening of SARS-CoV-2-infection-related clinical outcomes. The study highlighted the different roles of VOC, in particular Delta and wild-type, and being male and elderly in the development of a worse clinical outcome.

Exploring the effectiveness of the Digital Green Certificate Law as Public Health instrument to increase anti-COVID-19 vaccination in a sample of working-age adult population in the Palermo Metropolitan Area.

Counteracting vaccine hesitancy should be considered an absolute priority for Public Health Authorities. A correct health communication represents one of the best ways to increase adhesion to vaccination among hesitant population. In order to increase vaccination coverage rates against COVID-19, the Italian government has issued a legislative decree with a mandatory "Digital Green Certificate" (DGC) to access workplaces for some categories considered at risk. Methods: We conducted a cross-sectional study with the aim to highlight the factors associated with the anti-COVID-19 vaccine acceptance and to estimate the influence of the introduction by law of the Digital Green Certificate (DGC) on the adhesion to the COVID-19 vaccination campaign in a sample of individual accessing one of the main vaccination centres of the metropolitan area of Palermo, Italy. An anonymous and validated questionnaire was self-administered through the Google Documents® platform, between October 2021 and March 2022. Results: Among the 467 subjects enrolled, 43.3% were influenced on their vaccination choice by the introduction of the DGC. The multivariate analysis showed that among the respondents emerged contrasting feelings with a self-reported significantly higher sense of freedom (Adj-OR = 2.45, 95%CIs = 1.51-3.97, p-value: < 0.001) but a lower sense of safety (Adj-OR = 0.19, 95%CIs = 0.12-0.29, p-value: < 0.001) after vaccine administration. Conclusions: Our findings, in line with the available literature, suggest that the introduction of DGC has led to a significant increase in the immunization rate and, together with an appropriate communicative approach, it could represent an effective strategy to counteract vaccine hesitancy.