Results
Table 1 shows the patient characteristics of reported heart failure cases with all vaccines. Overall, no significant sex differences existed with about 53.8% of cases reported in males compared to 44.4% in females. The age group of 65 years and above constituted about 49.6% of cases while 37.7% and 6.9% lied within the 18-64- and 0-17-years age groups, respectively. Serious adverse events were reported in 86.8% of cases compared to 13.2% of non-serious events.
As shown in Table 2, the highest incidence of reported adverse events was associated with the COVID-19 vaccine (93.9%) with a remarkable significance. A distant second was the incidence associated with the Influenza vaccine (6.9%). Other reported vaccines included in descending order: zoster (3.1%), pneumococcal (2.9%), hepatitis B (2.3%), and smallpox (2.1%) vaccines. Next, we analyzed different types of heart failure associated with vaccines. While 60% of the reported heart failure are poorly defined, left ventricular failure was the most common type (10%) followed by right ventricular failure (5.5%). Acute exacerbation of heart failure reported among 8%. Interestingly, diastolic heart failure was twice more frequently reported (3%) compared to systolic dysfunction (1.5%) as shown in Table 3.
The patient characteristics of COVID-19 associated reported heart failure cases are shown in Table 4. About 55.5% of cases were reported in males compared to 43.5% in females. As with other vaccines, most reported adverse events were serious in about 88.8% of cases compared to 11.5% of non-serious cases. The highest number of reported cases was associated with the use of the Pfizer/Biontech vaccine with 1212 cases (61.93%). The Moderna vaccine was associated with 910 cases (46.5%) while the Jensen vaccine was associated with 169 cases (8.64%). Other manufacturers accounted for 0.36% of cases (Table 5).
Finally, we analyzed the reported odds ratio (ROR) of the most common vaccines compared the entire database. Individuals who received the COVID-19 vaccine had a significantly higher risk of developing heart failure with a ROR (CI 95%) of 21.6 (18.3 to 25.4) with P<0.0001. The second highest incidence was reported in association with the smallpox vaccine (7.2, 5.5-9.6, P < 0.0001). Interestingly, the risk of heart failure was significantly decreased in those receiving the hepatitis B (0.73, 0.6-9.22, P=0.0242), Influenza (0.71,0.6-0.8, P < 0.0001), and Zoster (0.6, 0.5-0.77, P < 0.0001) vaccines denoting possible cardioprotective properties. PPV vaccine recipients had the least likelihood of developing heart failure with an ROR of 0.1 (0.08-0.13, P<0.0001). Notably, the results of the influenza vaccine conform with research studies showing decreased morbidity and mortality among heart failure patients receiving the annual flu vaccine (12, 13).