How Effective Is the Flu Shot, Really?

The Centers for Disease Control (CDC) recommends that everyone six months and older get the flu (influenza) vaccination annually, especially those at risk from flu complications: older adults, pregnant women, caretakers of those at risk, and those with certain medical conditions.

Despite widespread recommendations, there are controversies regarding the flu shot's effectiveness.

It takes two weeks for complete protection after the flu shot. You can still get the flu during that window. Furthermore, 80 percent of all flu-like illnesses during flu season are due to viruses not included in the flu vaccine.

The CDC reports that approximately 200,000 and 36,000 individuals respectively are hospitalized or die annually from the flu. These statistics are based on people with influenza—as well as those who die from pneumonia and respiratory or circulatory illnesses, which the CDC counts as "probably" associated with influenza.

However, according to Barbara Loe Fisher, president of the National Vaccine Information Center (NVIC), the U.S. Vital Statistics Mortality Data reported only 600 to 750 average annual influenza deaths between 1995 and 2007. Fisher says the CDC acknowledges that most people it categorizes as dying from seasonal flu are not actually tested for the influenza virus.

Lawrence B. Palevsky, MD, says thousands of viruses exist around us all the time; exposure alone is not sufficient for us to get a viral illness. Furthermore, the mere presence of a specific virus in someone with flu-like symptoms does not prove causality. We also need a control group to evaluate the rate of that virus in health people.

Dr. Palevsky says multiple studies at the Cochran Vaccine Field in Italy demonstrate flu vaccines have little or no effect on reducing hospitalizations or deaths from flu, or reducing the incidence of flu. There is also little comparative evidence on the safety of the flu vaccine.

Physician Mark Hyman believes we shouldn't confuse ourselves about the pros and cons of a vaccine's worth, safety, and availability when we have so many ways to fight off the flu. Hyman urges us to consume fresh, nutritionally dense food, limit sugar and junk food, stay fit, and take a multi-vitamin, fish oil supplement, and extra vitamin D.

If you're considering a flu shot, the NVIC suggests you evaluate how much you know about the likely health outcome if do you experience a flu-like illness, and your odds of a full recovery (knowing the viruses in the vaccine are not the most likely to infect you). Also consider how much you know about the short- and long-term health outcomes of the vaccine.

Liesa Harte, MD, reviewed this article.


Palevsky, Lawrence B., MD, FAAP. "Swine Flu, Vaccines, Viruses and Fear." Web. November 2009.

Jefferson, T., Rivetti, A., Harnden, A., Di Pietrantonj, C., and Demicheli V. "Vaccines for Preventing Influenza in Healthy Children (Review)." The Cochrane Library V2 2008. Web.

Hyman, Mark, MD. "Should I Get the Flu Shot?"Blog. Web. 23 October 2012.

Centers for Disease Control. "Seasonal Flu Shot." Web. 6 December 2012.

Fisher, Barbara Loe. "Influenza Deaths: The Hype vs. The Evidence." National Vaccine Information Center. Web. 3 October 2012.