The vaccination campaign against COVID-19 in Italy has made it possible to avoid about 8 million cases, over 500,000 hospitalizations, over 55,000 hospitalizations in intensive care and about 150,000 deaths. The estimate, which refers to the period between 27 December 2020, the starting date of the vaccination campaign, and 31 January 2022, is reported in report ‘SARS-CoV-2 infections, hospitalizations and deaths associated with COVID-19 directly avoided by vaccination’ just published by the Istituto Superiore di Sanità.
The calculation was made with a methodology, initially developed for influenza vaccines but already applied in other countries for studies relating to SARS-CoV-2, which uses data from the Integrated Surveillance and the national vaccine register of the Ministry of Health. This approach is based on the idea that the weekly impact of vaccination on the events studied (COVID-19 notified cases, hospitalizations, ICU admissions and deaths) can be estimated by combining vaccination efficacy against the event of interest, coverage weekly vaccination and the weekly number of observed events.
This estimate is called direct as it does not consider the possible indirect impact of the same vaccination on the unvaccinated population (for example: the infections avoided among the vaccinated could have contained the overall transmissibility observed in Italy). The survey shows that from the beginning of the vaccination campaign to 31 December 2021, it is estimated that a total of 2.8 million cases (range 2.8 million-3.4 million), 290 thousand hospitalizations (218 thousand-400 thousand) have been avoided thanks to vaccination , 38 thousand hospitalizations in intensive care (27 thousand-54 thousand) and 78 thousand deaths (54 thousand-114 thousand). These figures represent respectively 43%, 58%, 57% and 64% of expected events (i.e. those observed plus those avoided).
Only in January 2022characterized by the predominance of the highly diffusive Omicron variant, in which a total of 4.3 million diagnoses of SARS-CoV-2 infection were observed, vaccination prevented a total of 5.2 million cases of infection (range 4.3 million-6.4 million), 228 thousand hospitalizations (161 thousand-384 thousand), 19 thousand hospitalizations in intensive care (13 thousand-31 thousand) and 74 thousand deaths (48 thousand-130 thousand).