“Flu shots”, also known as influenza vaccines, only protect patients from influenza, nothing more.

Flu shots, or influenza vaccines, are given annually just prior to the flu season, usually in mid to late Fall for those who reside in the northern hemisphere. Each year these vaccinations are reformulated to target the prevailing influenza virus types predicted to be epidemic for that season. Some influenza virus types cause more serious infection than others, so that severity of influenza illness may change from year to year. Some people are at greater risk of serious infection than others, such as those with underlying serious medical conditions, and those at the extremes of age. However, even susceptibility patterns may vary, as we saw recently the the H1N1 influenza virus. With H1N1, serious illness occurred more commonly in healthy young people, including teens and adults through age 49, pregnant individuals and infants.

For the United States, vaccination recommendations are provided by the Center for Disease Control, or CDC. These guidelines are utilized by most physicians and other providers when caring for patients.

Influenza vaccines are usually protective for influenza, however because each year the vaccine is reformulated based upon vaccine predictions, it occasionally fails to protect against certain virus strains. The vaccine is not a guarantee of protection.

As of 01/11/2013 the vaccine has been reported by the CDC to cover 62% of influenza virus strains.

The CDC also is reporting an exceptionally early start to the influenza season for 2012-2013. The circulating virus strains are unusually virulent, and have already caused widespread disease in several states.

United States Center for Disease Control Summary of influenza vaccination recommendations:

  • All people 6 months and older should be vaccinated annually, unless they have a rare and specific contraindication (for example, severe egg allergy, previous severe reaction to the vaccine, certain neurologic problems).
  • Protection of people at higher risk for influenza-related complications should continue to be a focus of vaccination efforts as providers and programs transition to routine vaccination of all people 6 months and older.
  • When vaccine supply is limited, vaccination efforts should focus on delivering vaccination to people who:
    • are 6 months to 4 years (59 months) of age;
    • are 50 years of age and older;
    • have chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders (including diabetes mellitus);
    • are immunosuppressed (including immunosuppression caused by medications or by human immunodeficiency virus);
    • are or will be pregnant during the influenza season;
    • are 6 months to 18 years of age and receiving long-term aspirin therapy and who therefore might be at risk for experiencing Reye’s syndrome after influenza virus infection;
    • are residents of nursing homes and other chronic-care facilities;
    • are American Indians/Alaska natives;
    • are morbidly obese (body mass index is 40 or greater);
    • are health care professionals;
    • are household contacts and caregivers of children aged younger than 5 years and adults aged 50 years and older, with particular emphasis on vaccinating contacts of children aged younger than 6 months;
    • are household contacts and caregivers of people with medical conditions that put them at higher risk for severe complications from influenza.

Despite these guidelines, there are many who question the necessity of influenza vaccination. Many are concerned about vaccine safety.

Rare, but serious, adverse events caused by these vaccines include:

  1. Severe allergy (egg allergy is a contraindication to flu vaccination)
  2. Stevens Johnson syndrome-a serious and potentially fatal skin reaction
  3. Guillain-Barre syndrome-a neurologic condition leading to paralysis and potentially respiratory failure (~1-10 cases per million vaccinations) Patients with a previous episode of this syndrome should not receive influenza vaccination.
  4. Thrombocytopenia, a blood disorder leading to potentially severe hemorrhagic events.

A few mild adverse symptoms are fairly common after vaccination, including fever, shivers, headache, myalgias, malaise, and local injection site reactions.

Controversial topics include the effects of thimerosol (mercury-based) preservative used in multidose vials of vaccine. While many countries have banned the use of thimerosol in vaccines, it is still commonly used in the United States. The rational for it’s use here is that it is thought to not build up in the body like regular mercury does (methylmercury). Autism, claimed by some to be caused by thimerosol, is officially thought not to be an effect of thimerosol because autism rates in children have increased, despite thimerosol being banned from use in children’s vaccines since 2001.

The upside to flu vaccination:

  • Minimizing the chance of acquiring influenza infection by you and possibly people whom you are in close contact with.
  • Avoiding 1-2 weeks of down time due to influenza illness, and further minimizing the chance of more rare more serious illness and even death associated with influenza epidemics.
  • Protecting yourself from the occasional more virulent strain of influenza.

So, should you get a flu shot this year?

Overall, the odds of a serious adverse event from vaccination are lower than the odds of acquiring severe influenza. Exact risk of each is difficult to accurately quantify since not all reactions and infections are reported for public health purposes, and because vaccine formulations, illness and epidemic severity varies with time.

The safest solution is to follow CDC guidelines. Unfortunately, a rare individual will suffer a serious adverse event, but far greater numbers of people will benefit by preventing influenza infection in themselves and possibly those around them, and serious infection and even deaths will be reduced overall.

Following recommendations based upon CDC guidelines provides the best odds for the individual and society as a whole, from a safety standpoint.

If you are still not convinced that a flu shot is for you, a few of the many questions you might ask yourself include:

  • Are you in close contact with people?
  • Do you work or live with children, the elderly, or those with serious medical conditions?
  • Do you handle money or other objects touched by others?
  • Are you a good hand washer?
  • Do you avoid touching your face and mouth?
  • Do you spend much time in enclosed public spaces such as airplanes, waiting rooms, etc.
  • Do you consider down time from illness unacceptable? Do you have work, school, business or other responsibilities that must be met with a high priority?
  • Do you have a winter vacation planned that you do not want to risk missing out on?
  • Do you travel in remote places without easy access to medical care?

If a virulent strain of influenza with a tendency to cause serious illness in young, healthy people becomes epidemic or even pandemic (worldwide spread), such as the 2009 H1N1 virus, are you willing to take this risk?

The CDC website is loaded with further information on influenza

Finally, consulting with a doctor who knows you best should provide valuable guiding insight for this potentially important health care decision.