Canadian researchers say people who receive a pneumonia vaccine may halve their risk of having a heart attack two years later. For the study, researchers compared 999 people admitted to Canadian hospitals for heart attacks with 3,996 admitted for other reasons. They found no difference between those who did or did not have the pneumonia vaccine in the previous year. But people who got the pneumonia vaccine two years earlier had a 50 percent lower heart attack rate. Pneumonia vaccines are...