Here at Johns Hopkins, the annual flu vaccination season is about to be undertaken. It is hospital policy that those who have contact with patients must receive an annual flu vaccine, but the pushback in some circles is ferocious. Even in this bastion of cutting edge medical and scientific endeavor, numbers of people submit that they can't or won't get a flu vaccine. While some arguments such as egg allergy are persuasive (although may soon be obsolete as flu vaccines will be raised using different techniques) others are more suspect, such as 'I got the flu from the vaccine.' Impossible, btw. Okay, rant recorded. What does this have to do with PodMed this week? Rick and I discuss a study in Heart, a BMJ journal, showing that among folks at risk for a heart attack or 'acute myocardial infarction,' or AMI, having a flu vaccine halved their risk of such an event. Yet one more reason to receive the vaccine, methinks.
Australian researchers recruited patients during three winter periods, when exposure to influenza circulating in the population at large was likely. 275 of these folks had an MI and were admitted to the hospital, while 284 were outpatient controls. About half of each group had received the influenza vaccine prior to study enrollment. Subjects were assessed for influenza infection, either laboratory-confirmed or self-report. Flu infection was found in 12.4% of folks who had had an MI and in 6.7% of controls. Unrecognized previous influenza infection was found in about 10% of study participants, conferring a two-fold increase in risk among those participants who were hospitalized for MI. Hmmmm. If you were told you could cut your risk of having a heart attack in half by having a flu shot, would that be compelling?
Certainly many criticisms could be leveled at this study, but lots of evidence points to the role of inflammation in precipitating cardiac events. Observational studies clearly demonstrate more MI during flu season, as well as secondary to other causes of inflammation such as air pollution. Inflammation is known to exacerbate conditions leading to heart attacks such as atherosclerosis. The authors interpret their study as evidence that vaccination guidelines in Australia should be expanded to include those younger than 65, who currently do not enjoy that status, but here in the US the Centers for Disease Control and Prevention has expanded their recommendations for flu vaccination to everyone over the age of 6 months. It's worth remembering that influenza infection often typically is more severe and can be life-threatening in those at the extremes of age, pregnant women and people with chronic medical conditions but certain flu strains, most notably the one that caused the 1918 flu pandemic, disproportionately killed young and middle-aged adults, whose robust immune response seems to have been the culprit. Thus it is the most protective for all of us if all of us get immunized.
Other topics this week include IV iron administration and infection in the BMJ , chronic kidney disease in blacks versus whites in JAMA, and the success of a comprehensive approach to blood pressure control in JAMA. Until next week, y'all live well.