Pneumococcal (pneumonia) vaccination was associated with a 50% lower risk of heart attacks 2 years after vaccination, suggests a large hospital-based case-control study published in CMAJ. http://www.cmaj.ca/press/pg773.pdf
In a population of patients at high risk of heart attack, the study compared the rates of pneumococcal vaccine between patients having a heart attack and patients without such an event.
"After a number of confounding and modifying variables were taken into account, the odds of having received a vaccination against S. pneumonia in the group who had experienced myocardial infarction was about half that in the control group," write Dr. Danielle Pilon and coauthors from the University of Sherbrooke and McMaster University. "Moreover, this association appeared stronger and the benefit appeared to increase with time since exposure to the vaccine."
In a related commentary http://www.cmaj.ca/press/pg749.pdf, Dr. Mohammad Madjid from the Texas Heart Institute hypothesizes that the pneumonia vaccine protects against heart attacks because it prevents pneumonia which has been shown to trigger heart attacks. Other studies suggest that respiratory (especially influenza) and urinary tract infections are associated with heart attacks. He suggests that physicians should focus on increasing vaccination rates against pneumonia and influenza in high risk patients as rates in the US and other countries are well below target goals.