Impact of the 2023/24 autumn-winter COVID-19 seasonal booster campaign in preventing severe COVID-19 cases in Italy (October 2023–March 2024)

: We assessed the impact of the 2023/2024 COVID-19 vaccination campaign in Italy by estimating the number of averted COVID-19 severe cases (i.e. COVID-19 associated hospitalisations or deaths) between October 2023 and March 2024, in those aged ≥60 years. We estimated that 565 (95 % CI: 497-625) cases, corresponding to 2.1 % (95 % CI: 1.8-2.3) of the expected cases without a vaccination campaign, were averted. We simulated three vaccination coverage scenarios: 50 %, 75 %, 90 % (versus the observed 10.7 %), finding that 9.7 % (95 % CI: 8.5-10.7); 14.5 % (95 % CI: 12.8-16.1); and 17.4 % (95 % CI: 15.3-19.3) of the expected cases would have been averted, respectively.