In-hospital influenza and COVID-19 vaccine availability during acute coronary syndrome boosts vaccination rates and improves outcomes versus out-of-season patients advised post-discharge vaccination

Introduction Current 2023 European Society of Cardiology (ESC) clinical practice guidelines for the management of acute coronary syndrome (ACS) recommend COVID-19 and influenza vaccination, preferably during the index hospitalization for those admitted in the influenza season. However, the benefits of the in-hospital vaccination strategy versus recommendations for vaccination post-discharge remain unclear. Purpose To compare, among patients who were recommended vaccination post-discharge (3 months pre-season) and those offered vaccination during hospitalization (seasonal period): the influenza and COVID-19 vaccination rates during the 2023-2024 season and the incidence of major adverse cardiac events (cardiovascular death, stroke, new ACS or unplanned revascularization) and or pneumonia hospitalization (MACEP) during first year after an ACS hospitalization, focusing on outcomes between 3 and 12 months post-discharge, when vaccines had been available for both groups. Methods Prospective, observational, single-centre study consecutive ACS patients discharged during the 3 months pre-season (1 August to 31 October) and the first 3 months of the 2023-2024 influenza season (1 November to 31 January). Post-discharge vaccination was recommended in the first period, while in-hospital vaccination was available upon physician request in the second. Vaccination rates and patient characteristics were compared. First MACEP incidence was analyzed during two intervals: 0-3 months and 3-12 months post-discharge, using Kaplan-Meier survival analysis. Results The study included 204 ACS patients: 102 (50%) discharged in each period. Overall, 98 (48%) patients received the influenza vaccine and 63 (31%) the COVID-19 vaccine during the 2023-2024 season. Vaccination rates were higher in the second period, with no other significant differences in clinical characteristics or treatment (table). Patients discharged during the seasonal period had significantly lower MACEP incidence between 3 and 12 months post-discharge (2 (2%: 2 ACS) vs. 12 (12%: 7 ACS, 2 strokes and 3 pneumonia hospitalizations), p=0.010, Figure). Conclusions Despite vaccination rate was low, in-hospital vaccine availability significantly increased it. This growth was associated with better prognosis compared with post-discharge recommendations outside the season. These findings support early in-hospital vaccination and highlight the need to improve vaccination strategies for ACS patients admitted outside the influenza season.