The Facts on Flu

By Dan Ketterer, MD

With the media focus on Ebola in the last several months, many people have not even thought about seasonal influenza and what it can mean for their health and the health of their loved ones. We are now in the midst of the 2014-2015 influenza season and Atlanta ID group would like to address some facts and misconceptions regarding influenza and its vaccination.

Influenza vaccine will not give you the flu.

All influenza vaccinations that are injected contain parts from killed or weakened influenza virus. You can not obtain the flu from the injected vaccine. An intranasal vaccine is available that does contain live weakened influenza virus. This vaccine is typically administered to children and those that do not like injections. The intranasal vaccine also does not cause influenza in those with healthy immune systems.

You may have had a friend or family member that got influenza symptoms after the flu vaccine. There are many possible explanations for this. The individual may have acquired another viral illness that mimics the flu. They may have experienced muscle soreness or aches which is a common reaction of the influenza vaccine (symptoms often disappear within a day and are improved by over the counter pain relievers). The influenza virus may have been acquired around the time of vaccination, or it was a strain not covered by the vaccine, which brings me to my next point.

Influenza vaccination is not 100% effective at preventing the flu.

During each flu season, there are numerous circulating strains of influenza. Influenza vaccines are prepared prior to the start of influenza season and use data from animals that also get infected with influenza to try to estimate which strains will predominate in the upcoming year. Occasionally, the vaccine does manage to correctly guess the major circulating strain (as in the case of the 2009 H1N1 strain) but frequently there are slight mutations in the virus which reduces, but does not eliminate the efficacy of the vaccine. By many estimates, the vaccine is between 40-50% effective at reducing your risk of developing influenza. Many stories have been circulating in the news about the 2014-2015 vaccine not covering the flu this year. This is not true. It is still early in flu season and most of the cases will come in Feburary-March of 2015. Most experts predict the predominant strain will be H3N2 strain which is included in the vaccine. There could be some mutations in the virus between now and the major months, but the vaccine is still effective in reducing symptom duration and severity of symptoms in strains with minor mutations.

You can obtain influenza vaccine if you are allergic to eggs.

You may remember being asked if you had an egg allergy before getting your influenza vaccine. Previously, all influenza vaccines were made by injecting the viral particles into chicken eggs. Now, egg free influenza vaccination is routinely available upon request.

Many of the deaths from influenza are due to exacerbation of existing medical conditions

Having influenza sharply increases your risk of fatal heart attacks and strokes. This is due to an inflammatory cascade triggered by an influenza virus infection that makes the individual more likely to form blood clots. Influenza vaccination is extremely important in individuals who suffer from heart or vascular diseases for this reason.

By obtaining the vaccine, you are helping your family and community as well.

The spread of many infectious diseases can be drastically reduced in a community by vaccinating the community against the disease. Even if one does only feel mildly ill with influenza, one can be highly contagious for a week and may put many others whose immune system is compromised such as diabetics, pregnant women, young children, or those chronic medical problems at risk for hospitalization from influenza.

Higher dose influenza vaccine works better in the elderly.

Recent data has suggested that high dose flu vaccine (marketed as Fluzone high dose) is approximately 24% more effective in those 65 years or older.   This is due to the immune system not providing as robust a protective response in advanced age. Asking your doctor for high dose flu vaccine if you are over 65 years of age may help in reduce your risk.

Getting infected with influenza does not provide immunity against reinfection.

While getting infected with influenza in a given year and overcoming the illness will confer a degree of immunity to the strain you were infected, it does not provide immunity to other circulating strains. This is why modern flu vaccines contain 3-4 different strains in each dose to cover against several circulating strains of influenza.

Vaccination saves a lot of time and morbidity.

The CDC estimates that in the 2012-2013 flu season alone, flu vaccinations prevented 6.6 million cases of influenza and stopped nearly 80,000 hospitalizations due to severe influenza. Without question, while the vaccine may not be completely efficacious, it does work and saves countless productivity hours. Why spend a week in bed with muscle pains and chills when you can get the flu vaccine and potentially prevent obtaining the illness? Time is of the essence as we are now in flu season. Obtain the vaccine now if you haven’t already to obtain maximal benefit.