Flu Vaccine may Protect Against Heart Attacks
Reported September 28, 2009
(Ivanhoe Newswire) -- Flu can trigger heart attacks and cause
cardiovascular death, but the influenza vaccine may offer protection for
Researchers say greater efforts are needed to encourage people with heart
disease and diabetes (which increases the risk of heart attacks) to have the
flu shot, especially with the looming double-whammy of the H1N1 influenza
(swine flu) pandemic and seasonal flu outbreaks.
The cardiac complications of influenza infection, such as myocarditis, are
well known, but the role of influenza as a trigger of heart attacks is less
clear. It has been suggested that influenza might cause acute and severe
inflammation, which in some patients may destabilize atherosclerotic plaques
and cause clots in coronary arteries leading to heart attacks.
Charlotte Warren-Gash and Andrew C. Hayward from the UCL Centre for
Infectious Disease Epidemiology, London, and Liam Smeeth from the London
School of Hygiene and Tropical Medicine, conducted a systematic review of
the evidence to examine the association between influenza and heart attacks
or cardiovascular death, including the possible cardio-protective effects of
the influenza vaccine. They analyzed 42 papers describing 39 studies between
1932 and 2008.
All the population-level studies showed a rise in deaths due to heart
disease or heart attack during times when the influenza virus was
circulating. The proportion of excess influenza deaths that were due to
heart disease averaged 35 percent.
Four out of eight studies also showed a protective effect against heart
attacks or cardiovascular events in those vaccinated against influenza. In
addition, two small randomized trials suggested that influenza vaccination
reduces the risks of cardiovascular death and some cardiac events.
The authors concluded: "We believe influenza vaccination should be
encouraged wherever indicated, especially in those people with existing
cardiovascular disease. . . . Further evidence is needed on the
effectiveness of influenza vaccines to reduce the risk of cardiac events in
people without established vascular disease."
SOURCE: The Lancet Infectious Diseases, October 2009