How Effective Is A Flu Shot?

Flu season is right around the corner. That’s why the CDC (Centers for Disease Prevention and Control) “recommends a yearly flu vaccine for everyone 6 months of age and older as the first and most important step in protecting against this serious disease.” But how good is the flu shot when it comes to protecting against influenza or the complications of this viral infection?
The CDC’s answer to this question is ambiguous at best. Our premier public health organization says that effectiveness of the vaccine “can range widely from season to season.” If the match between the shot and the circulating viruses is bad, “It’s possible that no benefit from the vaccination may be observed.” If the match is very good, “substantial benefits” in preventing flu are observed. What does that really mean?
A brand new study by a leading infectious disease epidemiologist casts more doubt on the benefits of the flu vaccine. Michael Osterholm, PhD, M.P.H., is a prominent public health scientist. He and his colleagues reviewed 5,707 influenza articles in the medical literature that were published between Jan. 1, 1967 and Feb. 15, 2011 (The Lancet Infectious Diseases, online Oct 26, 2011). From that enormous number they narrowed their analysis down to 31 of the absolute best studies.
Of those top-notch investigations, there were 10 randomised, controlled trials that could be analyzed for overall efficacy. What Dr. Osterholm and his colleagues found was that together, the benefit was 59%. In other words, 41% of the people who got a flu vaccine experienced no protection against influenza.
In our opinion that’s disappointingly low. If your toaster only toasted your bread a little more than half the time you would demand your money back. Perhaps even more disheartening is the observation that there were no good trials for children between the ages of 2 and 17 or adults over the age of 65. Those are precisely the groups that are most vulnerable to complications from influenza.
This isn’t the first big study to suggest that the flu vaccine leaves a lot to be desired. An analysis in the Journal of Infectious Diseases (Jan. 15, 2010) concluded that when it comes to senior citizens: “the ‘effectiveness’ of the vaccine is in great part due to the selection of healthier individuals for vaccination, rather than due to true effectiveness of the vaccine” (Journal of Infectious Diseases, Jan. 15, 2010).
Even healthy younger people don’t have fewer sick days, shorter hospital stays or fewer deaths from influenza if they get vaccinated (British Medical Journal, Oct. 28, 2006).
Questions also persist about the benefits of flu shots for babies and toddlers under two. Although they are more vulnerable to influenza complications, the data suggest that most flu vaccines are not terribly effective for these young ones (Cochrane Database Systematic Reviews, April 16, 2008).
The authors of the most recent study in The Lancet Infectious Diseases call for improved vaccinations. We couldn’t agree more. It is sad that after so many years we still lack a highly effective flu shot.
What can people do while we wait for something better? We think that at this time of year vitamin D supplementation makes a lot of sense. Grandmothers all over the world knew that in the fall and winter they needed to encourage their children and grandchildren to take cod liver oil. They didn’t know why, but they frequently dosed the family with foul-tasting cod liver oil, which contained vitamin D as well as omega-3 fatty acids. This was especially true in northern countries like Scandinavia where sunlight is in short supply at this time of year.
Research now suggests that the grandmothers were on to something. A study published in the British Journal of Nutrition (June, 2011) concluded that there is a strong relationship between vitamin D levels, respiratory infections and lung function. An article published in Epidemiology and Infection concluded that “Vitamin D deficiency predisposes children to respiratory infections…An interventional study showed that vitamin D reduces the incidence of respiratory infections in children.” The same authors concluded in the journal Alternative Medicine Reviews that “Theoretically, pharmacological doses of vitamin D may produce enough of the naturally occurring antibiotic cathelicidin to cure common viral respiratory infections, such as influenza and the common cold, but such a theory awaits further science.”
So science is beginning to catch up with grandma. The doctor could also prescribe an antiviral drug such as oseltamivir (Tamiflu), amantadine, rimantadine or zanamivir (Relenza) to help some people recover from influenza faster than they normally would.
Ultimately, we do need a better influenza vaccine. In the meantime, though, there are some things that may help you avoid the flu. Wash your hands religiously. Consider every surface you touch when you are out in public a possible source of flu virus–that includes gasoline pump handles, ATM buttons and banisters. Keep your fingers out of your eyes and nose, no matter how good a job you do washing your hands.
If you have any question about vitamin D, you can get a blood test for 25-hydroxyvitamin D. Keep your levels above 20 ng/ml. Some health experts recommend levels above 30 ng/ml at this time of year. If flu is widespread in your community and you start to feel ill, ask your MD about a rapid flu test and inquire if a prescription is warranted for one of the antiviral medications.