• Influenza infection [ Time Frame: 6 months ] [ Designated as safety issue: No ]
  
• Serologic response (≥4-fold HI titer rise) to each of the 3 antigens of the trivalent vaccine of the 2006-07 campaign [Solomon Islands/3/2006(H1N1), Wisconsin/67/2005 (H3N2), and Malaysia/2506/2004 - like strains] [ Time Frame: 1 month ] [ Designated as safety issue: No ]
  

• Magnitude of change in the antibody titer against each of the three influenza vaccine antigens [ Time Frame: 1 month ] [ Designated as safety issue: No ]
  
• Protective antibody (≥1:40) titer after vaccination [ Time Frame: 1 month ] [ Designated as safety issue: No ]
  
• Influenza-related death [ Time Frame: 6 months ] [ Designated as safety issue: No ]
  

Influenza infection may become complicated in patients with chronic conditions, including coronary artery disease (CAD) [1]. Influenza vaccination is now recommended as part of comprehensive secondary prevention in individuals with coronary and other atherosclerotic vascular disease (evidence level: Class I, Level B) [2]. Although there is controversial evidence pro [3,4] and against [5] the efficacy of influenza vaccination in protecting CAD population against cardiovascular events, the efficacy of vaccine in actual reduction in episodes of influenza infection and its fatal complications in CAD patients has not been, to our knowledge, well studied before. Furthermore, we found no report comparing serologic response to the influenza vaccine antigens between CAD patients and healthy controls.

This study aims to identify the efficacy of influenza vaccination in CAD individuals in terms of both serologic response (as compared with healthy individuals) and clinical outcomes (as compared with CAD patients not vaccinated).

Inclusion Criteria:

Coronary artery disease (CAD) group (CAD-Exp and CAD-Control):

• Patients with the diagnosis of acute, evolving or recent MI (after recovered the acute phase) as defined by:

  1. Typical rise and gradual fall (troponin) or more rapid rise and fall (CK-MB) of biochemical markers of myocardial necrosis with at least one of the following:

• Ischemic symptoms
• Development of pathologic Qwaves on the ECG
• ECG changes indicative of ischemia (ST segment elevation or depression); OR

• Coronary artery intervention (e.g., coronary angioplasty).

  2. Pathologic findings of an acute MI [1]:

• Patients with stable angina pectoris (SA) and documented coronary artery stenosis (angiography).

Healthy Control group: healthy controls, proportionally matched by gender and age with the patient group (separate control groups for MI and SA patients).

Exclusion Criteria:

• Any acute disease
• Chronic liver or kidney diseases
• Conditions accompanied by immunosuppression (like organ transplantation, HIV)
• Diagnosed malignancy
• Incubation with influenza vaccine within the past 5 years
• Any psychological disease that interferes with regular follow-up
• Congestive heart failure (Killip class IV)
• Unstable angina; AND
• Contradictions of vaccine incubation (like egg allergy).