Associations between Combined Influenza and Pneumococcal Pneumonia Vaccination and Cardiovascular Outcomes
Authors: Ma Jennifer , Mena Miguel , Mandania Roshni A. , Ghosh Arjab , Dodoo Christopher , Dwivedi Alok K. , Mukherjee Debabrata 
Published: September 2021

<b><i>Background:</i></b> In 2017, the CDC listed heart disease as the leading cause of death, with pneumonia and influenza being the eighth cause of death. Several studies have suggested the protective effects of influenza vaccination on myocardial infarction (MI). Available evidence supports the use of influenza vaccination in decreasing cardiovascular events, and the Joint Commission considers influenza vaccination a metric of quality care for hospitalized patients. Our specific aim was to evaluate the combined use of pneumococcal pneumonia vaccine (PPV) and influenza vaccine on cardiovascular outcomes and mortality. <b><i>Methods:</i></b> A retrospective observational study was conducted using the 2012–2015 US National Inpatient Sample (NIS) database, to compare cardiovascular events in adult patients who did and did not receive vaccination during their hospitalization. ICD-9 codes were used to extract data for specific variables. The outcomes included MI, transient ischemic attacks, cardiac arrest, stroke, heart failure, and death. Adjusted relative risks (RR) were calculated using survey-weighted generalized linear models after adjusting for gender, race, socioeconomic status, diabetes, hypertension, hyperlipidemia, smoking status, prior coronary artery disease, and cerebrovascular disease. The effect of vaccination on in-hospital mortality was assessed in each subgroup of cardiovascular events using RR regressions. <b><i>Results:</i></b> This study included 22,634,643 hospitalizations, of which 21,929,592 did not receive immunization. Vaccination solely against influenza was associated with lower MI (RR = 0.84, 95% CI: 0.82–0.87, <i>p</i> &#x3c; 0.001), TIA (RR = 0.93, 95% CI: 0.9–0.96, <i>p</i> &#x3c; 0.001), cardiac arrest (RR = 0.36, 95% CI: 0.33–0.39, <i>p</i> &#x3c; 0.001), stroke (RR = 0.94, 95% CI: 0.91–0.97, <i>p</i> &#x3c; 0.001), and mortality (RR = 0.38, 95% CI: 0.36–0.4, <i>p</i> &#x3c; 0.001). Vaccination with PPV alone was associated with MI (RR = 1.13, 95% CI: 1.11–1.16, <i>p</i> &#x3c; 0.001), TIA (RR = 1.28, 95% CI: 1.26–1.31, <i>p</i> &#x3c; 0.001), stroke (RR = 1.21, 95% CI: 1.18–1.24, <i>p</i> &#x3c; 0.001), and lower mortality (RR = 0.47, 95% CI: 0.45–0.49, <i>p</i> &#x3c; 0.001). Combined PPV and influenza vaccine was associated with lower mortality (2.21% vs. 1.03%, <i>p</i> &#x3c; 0.001) and lower cardiac arrest (0.61% vs. 0.51%, <i>p</i> &#x3c; 0.001). In the adjusted analysis, the RR was 0.46 (95% CI: 0.43, 0.49) for mortality in the combined vaccinated cohort. The combined vaccination group also had a significantly reduced risk of mortality among those admitted with MI (RR = 0.46), transient ischemic attacks (RR = 0.58), and stroke (RR = 0.42) compared to the nonvaccinated group. <b><i>Conclusions:</i></b> Our study shows a significantly reduced risk of mortality with influenza vaccine and PPV and with combined pneumococcal and influenza vaccination. These data suggest that in-hospital administration of pneumonia and influenza vaccines appears safe and supports the use of combined vaccination during hospitalization due to their cardiovascular benefits.