Vaccination and variants: Retrospective model for the evolution of Covid-19 in Italy
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Abstract
The last year of Covid-19 pandemic has been characterized by the continuous chase between the vaccination campaign and the appearance of new variants that puts further obstacles to the possibility of eradicating the virus and returning to normality in a short period. In the present paper we develop a deterministic compartmental model to describe the evolution of the Covid-19 in Italy as a combined effect of vaccination campaign, new variant spreading and mobility restrictions. Particular attention is given to the mechanism of waning immunity, appropriately timed with respect to the effective progress of the vaccination campaign in Italy. We perform a retrospective analysis in order to explore the role that different mechanisms, such as behavioral changes, variation of the population mobility, seasonal variability of the virus infectivity, and spreading of new variants have had in shaping the epidemiological curve. We find that, in the large time window considered, the most relevant mechanism is the seasonal variation in the stability of the virus, followed by the awareness mechanism, that induces individuals to increase/relax self-protective measures when the number of active cases increases/decreases. The appearance of the Delta variant and the mobility variations have had instead only marginal effects. In absence of vaccines the emerging scenario would have been dramatic with a percentage difference in the number of total infections and total deaths, in both cases, larger than fifty per cent. The model also predicts the appearance of a more contagious variant (the Omicron variant) and its becoming dominant in January 2022.
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SciScore for 10.1101/2022.02.27.22271593: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics not detected. Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Table 2: Resources
No key resources detected.
Results 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:The model has some limitations. The first one is that the system is assumed to be closed and protected from the injection of new cases from abroad. This circumstance is not fully justified, specially in the summer period, when the touristic flows increase. …
SciScore for 10.1101/2022.02.27.22271593: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics not detected. Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Table 2: Resources
No key resources detected.
Results 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:The model has some limitations. The first one is that the system is assumed to be closed and protected from the injection of new cases from abroad. This circumstance is not fully justified, specially in the summer period, when the touristic flows increase. However, according to data published by ISTAT (National Institute of Statistics), even if the international tourist flow in 2021 was in recovery with respect to the year 2020 (+22, 3%), it was still far from the levels of 2019 (−38, 4%) [56]. The extension of the model to open system is left to future work. Secondly, it has been shown that the vaccine efficacy to protect against severe infections is higher than the efficacy against mild or asymptomatic infection. Our model doesn’t distinguish the symptomatic cases according to the severity of symptoms, being pauci, mild and severe symptomatic cases, as well as hospitalized cases, all included in the symptomatic compartment. It would be interesting to rearrange the model in order to measure differences in hospitalization and severity of symptoms between vaccinated and unvaccinated individuals. However this would involve the introduction of new compartments into the model, circumstance that we avoided in order to keep the model simpler in the present paper. In [57] authors study the attenuation of antibody titres after the second dose, showing that the most important factor in determining the waning immunity is sex, age and smoking. Our model does not take into account the ag...
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.
Results from scite Reference Check: We found no unreliable references.
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