Pneumococcal vaccine and risk for CVA: trying to sort the data

Heart attack and stroke risk related to a common vaccine for pneumonia brings questions to the forefront and leaves many looking for more answers.

The debate over whether or not the pneumococcal vaccination raises the risk for heart attack and stroke events in men is a controversial one to say the least.  There is documentation showing that pneumoccal pneumonias themselves–not the vaccine–can trigger an inflammatory response that could lead to the buildup of fatty plaque within the arteries.  This buildup is known to lead to the occlusion of blood flow to the heart, or break off and lodge in vessels of the brain, resulting in heart attacks or stroke.  Investigations into how the body reacts to the stress of a pneumococcal pneumonia continue to be investigated.  However a study published in the Journal of the American Medical Association presents some obviously concerning data on the issue, then phrases the results so that more questions are raised than answered.

Each year in this country, there are an estimated 175,000 cases of pneumococcal pneumonia.  Caused by the bacteria Streptococcus pneumoniae, the condition may occur in conjunction with other illnesses like meningitis or bacteremia.  Pneumococcal pneumonia , which is most common in children younger than two and adults over the age of 65, presents with a sudden onset of symptoms including fever, cough, shortness of breath, and sometimes chest pain.  The development of a vaccine for this particular type of pneumonia has been beneficial to some but now a few studies are beginning to explore the link between the vaccine and its link to the risk of heart attack and stroke events in men.

The study, published in a 2010 edition of JAMA, looks at a cohort study conducted by Kaiser Permanante Northern and Southern California health plans and gathered data regarding cardiac events in both vaccinated and un-vaccinated adult men.  The study looked at over 84,000 participants between the ages of 45 and 69 years, and followed them from 2002 to 2007.  None of the men in the study had any history or heart disease or previous heart attack.  According to the study, rate of heart attack in vaccinated men was 10.73% per 1,000 person-years.  In unvaccinated men, the rate was 6.07% per 1,000 person-years.  Stroke events presented at 5.3% in vaccinated men, and 1.9% in unvaccinated men.   Personal interpretation of this data may seem simple and clear cut.  But the study authors concluded not that there was any increased risk, but instead chose to phrase the data as “…receipt of pneumococcal vaccine was not associated with subsequent reduced risk of acute MI and stroke.”

If the pneumococcal vaccine is not associated with a reduced risk, then one may consider it to be associated with an increased risk, or chose to draw no conclusions at all until further studies have been conducted.  As more data is gathered and future studies explore the issue, yet another debate over vaccine safety rages on.