Systemic infection is associated with heart attacks and strokes. The mechanisms, according to Reference 1, include inflammation and biomechanical stress on the coronary arteries. During the first three days of a respiratory infection, there is an increased risk of cardiovascular and cerebrovascular events. Thus, researchers in Hong Kong hypothesized that vaccines for pneumonia and influenza may prevent hospitalization and death from heart attack and stroke in adults over age 65 at risk. Their study of 36,636 subjects indicated they were right.
Pneumonia vaccination rates are low in Hong Kong, so this location was ideal for the study. Researchers recruited the test subjects from patients age 65 and older who visited the Hong Kong West cluster of outpatient clinics, with at least one of the following conditions: asthma, chronic obstructive pulmonary disease (COPD), coronary artery disease, high blood pressure, diabetes mellitus, stroke, chronic kidney or liver disease, or cancer. All were invited to receive both vaccines, and all were monitored for 64 weeks after enrolling in the study.
Subjects who received both vaccines had a 48 percent reduction in heart attacks (acute myocardial infarction), a 33 percent reduction in ischemic stroke, and a 35 percent reduction in ischemic heart disease, compared to the unvaccinated group. The overall death rate during the study was 35 percent reduced for the group with both vaccines.
A limitation of the study is that the subjects were not randomized, for ethical reasons. However, the baseline characteristics were well-matched for each group:
1. Unvaccinated, 25,393 subjects
2. Dual vaccine group, 7,292 subjects
3. Influenza vaccine only group, 2,076 subjects
4. Pneumonia vaccine only group, 1,875 subjects
Results for the groups with only one vaccine were intermediate between the unvaccinated and dual vaccine groups.
In the United States, the Centers for Disease Control Advisory Committee on Immunization Practices recommends one dose of the pneumonia vaccine PPSV23 for adults 65 or older.