UK : Research does not prove cause and effect , researcher says . The study , published Monday in the Canadian Medical Association Journal , was conducted to add to other studies that suggested that there is a link between respiratory infections and heart attacks . UK researchers say flu vaccine is associated with a 19 percent drop in first time heart rate . Researchers studied a large group of people aged 40 and older .
UK : Research does not prove cause and effect , researcher says . UK researchers say flu vaccine is associated with a 19 percent drop in first time heart rate . Researchers studied a large group of people aged 40 and older .