In a paper published in MedRxiv are analyzed the effectiveness of the first six months of vaccination campaign against SARS-CoV-2 in Italy by using a computational epidemic model which takes into account demographic, mobility, vaccines, as well as estimates of the introduction and spreading of the more transmissible Alpha variant.

Are considered six sub-national regions and study the effect of vaccines in terms of number of averted deaths, infections, and reduction in the Infection Fatality Rate (IFR) with respect to counterfactual scenarios with the actual non-pharmaceuticals interventions but no vaccine administration. Furthermore, are compared the effectiveness in counterfactual scenarios with different vaccines allocation strategies and vaccination rates.

The results suggest that vaccines avoided 29, 350 (IQR: [16, 454−42, 826]) deaths between 2020/12/27- 2021/07/05. This is about 50% of the number of deaths reported in the country during the same period.
If we look at the different regions considered, 8, 877 (IQR: [5, 502 − 12, 429]) deaths were averted in North West, 3, 121 (IQR: [498 − 6, 035]) in North East, 6, 498 (IQR: [4, 144 − 8, 700]) in Center, 7, 960 (IQR: [4, 885 − 11, 216]) in South, 2, 253 (IQR: [1, 206 − 3, 314]) in Sicily, and 640 (IQR: [219 − 1, 132]) in Sardinia.

To give a better idea, these numbers (medians) corresponds to the following percentages of the total number of deaths observed in the regions during the same period: 58% in North-West, 20% in North East, 60% in Center, 65% in South, 63% in Sicily, and 77% in Sardinia.

Similarly, 4, 256, 332 (IQR: [1, 675, 564 − 6, 980, 070]) infections were avoided in the country, divided into the different regions as follows: 987, 556 (IQR: [226, 372 − 1, 760, 203]) in North West, 482, 314 (IQR: [72, 632 − 975, 406]) in North East, 865, 176 (IQR: [474, 062 − 1, 282, 665]) in Center, 1, 296, 823 (IQR: [584, 453 − 2, 042, 629]) in South, 450, 259 (IQR: [246, 653 − 642, 726]) in Sicily, and 174, 204 (IQR: [71, 392 − 276, 441]) in Sardinia.

During the same period, was achieved a −22.2% (IQR: [−31.4%; −13.9%]) reduction in the IFR.
Furthermore, our results suggest that vaccines prevented an additional COVID-19 wave.

Acampaign that would have strictly prioritized age groups at higher risk of dying from COVID-19, besides frontline workers, would have implied additional benefits both in terms of avoided fatalities and reduction in the IFR. Strategies
targeting the most active age groups would have prevented a higher number of infections but would have been associated with more deaths.

Finally, were studied the effects of different vaccination intake scenarios by rescaling the number of available doses in the time period under study to those administered in other countries of reference. The modeling framework can be applied to other countries to provide a mechanistic characterization of vaccination campaigns worldwide.