Flu season is here again. Every year from around October through March, the seasonal flu can bring on several days of familiar symptoms: cough, sneeze, chills, fever, and body aches. Misery and missed work or school days follow. Most people think of influenza as a benign disease, perhaps no worse than a cold, that causes temporary discomfort.

But in fact, the flu can be severe and is a leading cause of hospitalization and death in the United States. One study estimated that 200,000 people are hospitalized every year because of flu and flu-related complications, such as pneumonia. In 2009, influenza and pneumonia were the eighth leading cause of all deaths in the nation.

The influenza virus is spread by tiny droplets from an infected person coughing, sneezing, or even talking. Infection is also spread by touching a surface or object with the virus on it. Preventing infection involves good every day health habits – washing your hands frequently with soap and water and covering your nose and mouth when coughing or sneezing. Since influenza is contagious even before symptoms are present, it is sensible to make good health habits a common personal practice. It is also important to stay home if you are sick to avoid spreading the virus to others.

However, the best way of reducing the chance that you will get flu and spread it to others is to get vaccinated. The Centers for Disease Control and Prevention (CDC) recommends flu vaccination for all persons older than 6 months. The flu vaccine is safe; hundreds of millions of doses have administered over the years with relatively few side effects. The vaccine is reasonably effective, conferring protection from illness in 60 to 70 percent of all recipients. Among children, the vaccine is effective 70 to 80 percent of the time. Nevertheless, many people still have sensible questions about the vaccine and the value of being immunized. Some of those questions are answered here.

Can the vaccine give me the flu?

The flu shot contains inactivated, killed viruses that are incapable of causing disease. Exposure to these incapacitated viruses will boost your immune system so that if you encounter a live virus at home or in the community, you can fight it off better and prevent illness. The nasal-spray form of the vaccine, known as FluMist, contains weakened, live viruses but has not been shown to cause illness in healthy people. FluMist is particularly effective in children and certainly easier to administer than an injection.

Can I get the flu even if I’m vaccinated?

The flu vaccine does not work right away. It is possible to become infected with influenza if you are exposed to the virus during the 10-14 day period after vaccination before your body has developed a full immune response. Also, the vaccine will not protect against other viruses that cause flu-like illnesses but are not the flu virus.

It may also happen that a variation of the flu virus – one that is different than the ones in the vaccine – appears during the flu season. The viruses used in the vaccine are chosen months ahead of the start of the flu season to allow time for vaccine production. Every year, scientists from the World Health Organization (WHO), the CDC and the U. S. Federal Drug Administration (FDA) study virus samples from around the world to determine which flu viruses should be included in the vaccine for the Northern Hemisphere.

This year’s vaccine contains three viruses. One virus is similar to the H1N1 virus that caused the 2009 swine flu outbreak in the U.S. and other countries. The other two viruses are seasonal flu viruses that have been prevalent in other countries over the past year. Based on worldwide patterns of disease, these three viruses are thought to be the ones most likely to cause disease in the U.S. Since most flu viruses are similar, however, getting the vaccine should provide some cross-protection and make the illness less severe if you happen to become infected by a non-vaccine virus.

If the vaccine isn’t 100% effective, why bother?

The vaccine will provide protection against the viruses that experts believe are most likely to cause illness this season. It is true that vaccine effectiveness varies from year to year, because no one can know before the flu season starts whether the viruses in the vaccine will exactly match the viruses in circulation. This inherent uncertainty, however, should not be seen as a reason to remain unprotected against the viruses most likely to cause disease, because flu-related complications can cause serious illness. For older persons, flu-related pneumonia can result in hospitalization and even death. Flu can also cause ear infections, sinus infections and exacerbate chronic health conditions, such as asthma. This results in time lost from work and school, and time needed to visit health-care providers and to obtain prescription or over-the-counter medications.

Aren’t there bad side effects from a flu shot?

Most flu vaccination reactions are mild and most often consist of soreness, swelling and redness at the injection site. Other adverse reactions are rare and everyone should weigh the risk of an uncommon reaction against the risk of remaining unvaccinated and getting flu and flu-related complications. The reactions are rare, the flu is not.

The Vaccine Adverse Event Reporting System (VAERS) keeps detailed information about vaccine reactions. Although severe allergic reactions can occur in response to a number of components in the flu vaccine, they are not common. Anyone who has previously had such a reaction is advised to talk with their care provider about receiving the vaccine. In addition, anyone who believes they are allergic to eggs should also talk with their care providers. Influenza vaccines are produced by growing the virus in chicken eggs. This sounds strange, but it is true. It turns out that eggs provide the perfect environment for growing the virus. But this method of vaccine preparation may put those with allergies to egg proteins at risk for an adverse reaction.

In past years there was concern that thimerosol, a mercury-based compound that is used in some vaccines as a preservative, may be related to the onset of autism in children. Research has shown thimerosol to be unrelated to autism. However, out of an abundance of caution, as of 2001, flu vaccines for children and most vaccines for adults contain either no thimerosol or only trace amounts of it. Research has also shown no association between the flu vaccine and asthma.

There also have been concerns that specific vaccines, such as the measles, mumps and rubella (MMR) vaccine, cause autism in children for reasons unrelated to thimerosol. Research over the past ten years has shown no link between vaccines and autism. The original research suggesting such a connection has been debunked and proven fraudulent, and the researcher has been discredited.

Why do I need a flu shot every year?
The vaccine protection wears off after a few months and does not carry over to the next season; therefore, revaccination is required every year.  In addition, the flu virus changes from year to year and so this year’s vaccine is unlikely to be exactly the same as next year’s.

The flu vaccine is not perfect and we do need to develop more efficient and faster ways to produce it. However, the vaccine is safe and everyone must weigh the perceived costs of immunization against the very real costs of being ill from flu with missed work and school days and possible complications. Please visit for more information about influenza and flu vaccination.

Patti Culross, M.D., Master of Public Health, is a preventive medicine physician and a former program director for the Los Angeles County Department of Public Health. She is the sister of Rafu sports editor Mikey Hirano Culross and writes from Glendale. Opinions expressed in this column are not necessarily those of The Rafu Shimpo.

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