Don’t Get Caught! Get the Flu Shot!

If you are a flu shot skeptic, now is a good time to shed your bias and go get that flu shot. A growing body of evidence shows that not only can it prevent a severe episode of flu, but may also increase the lifespan in some cases, especially for patients with heart failure.

The vaccine, usually given in the form of an injection, contains small amounts of deactivated flu viruses. These viruses are not harmful in this state but do trigger the human body to produce antibodies to fight against them. This means that the next time the virus enters the body, it can produce the same response quickly. The Centers for Disease Control and Prevention (CDC) advise that everyone over the age of 6 months has a flu vaccination. However, certain individuals are more at risk of experiencing flu-related complications or even death. This includes people over 65 years old and over, those who are pregnant, and those who have medical conditions, such as heart disease.

Particularly, for patients with heart failure, influenza can be very serious or even fatal because they are often older than 65, and their heart no longer pumps blood efficiently. The flu can exacerbate symptoms of heart failure. Moreover, heart failure is expected to increase over the next decade as the population ages, highlighting a greater need to provide better care for these patients.

In a recent study, published in the journal Circulation, researchers analyzed data on 134,048 patients with newly diagnosed heart failure in Denmark over a 12-year period. The researchers gathered the data from several national registries that store information on hospital diagnoses, prescriptions, and causes of death. Each person born in Denmark receives a unique personal identification number, and this number allowed researchers to follow particular people for 12 years, from 2003 to 2015.

Flu vaccination rates ranged from 16 percent in 2003 to 52 percent in 2015 with a peak of 54 percent in 2009. They found:

  • Annual flu vaccination following a heart failure diagnosis was associated with a 19 percent reduction in both all-cause and cardiovascular death when compared with no vaccination.
  • Flu vaccination frequency mattered; getting a flu shot less than once per year but more than not at all was associated with a 13 percent reduced risk of all-cause death and an 8 percent reduced risk of cardiovascular death.
  • Timing mattered; there was a greater reduction in cardiovascular and all-cause death when vaccination occurred earlier in the flu season during September and October versus in November and December.

While this research only looked at patients with newly-diagnosed heart failure, the protection from a flu shot likely benefits any patient with heart failure.

For patients with heart failure who do get the flu, a new analysis shows just how much sicker it can make hospitalized patients, providing further argument for routinely offering flu vaccination to patients with heart failure after admission or in the community. The analysis is based on more than 8 million records for adults hospitalized with HF in 2013 and 2014 in the National Inpatient Sample (NIS), a US database; they included 54,590 cases (0.67%) of patients who also had the flu.

In the propensity-matched analysis involving more than 100,000 heart failure hospitalizations, the patients who also had the flu were not only more likely to die in hospital, they had much higher rates of acute respiratory failure, whether or not it required mechanical ventilation. Their risk of acute kidney injury was also significantly increased.

Vaccination against influenza is one of the best ways to mitigate the increased risk posed by it in patients with heart failure. Low vaccination rates in such a vulnerable population provide a substantial public health improvement opportunity. Its not too late. Go get your shot now.

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