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The flu and you

Mark Jansen
By Mark T. Jansen, M.D. 
Vice President & Chief Medical Officer 
Arkansas Blue Cross and Blue Shield

This is the time of year when “get your flu shot” campaigns start again, and we all wonder what kind of a flu season this one will be.

I thought it might be helpful to share a few flu facts then discuss issues related to the vaccine. Influenza is primarily a respiratory illness caused by a multitude of viruses under two general categories (A and B).

Kinds of flu

As a rule, A types result in more severe symptoms, as opposed to B. In the northern hemisphere, flu typically starts in October, and cases can continue through May. There are several types of vaccines, but I will stick to the most common, which is called an “inactivated” vaccine. The inactivated vaccine is made by killing the active virus and purifying the antigens (or “fingerprints”) of the virus to use in the injection. (More about that later.)

Did you ever wonder why strains of the flu are identified by city or state names? The names are derived from the location where the new strain is first identified. This year, the vaccine will help protect against four strains predicted to be around this season. A/Brisbane (in Australia), A/Kansas, B/Colorado and B/Phuket (in Thailand).

How the flu vaccine works

To make the vaccine, the virus antigens are extracted, purified then injected with the vaccine. Since the virus is inactivated, you cannot get the flu from the vaccine. Older production methods were not so precise, so if your granddad swore he got the flu from the shot, he might have been right.

When our immune systems see the fingerprints, they know that specific virus is in the vicinity and make protective antibodies to shield against the virus. Over time, the level of antibodies decline, so the idea is to maximize the antibody level when flu is most prevalent in communities. This is why the vaccine is annual. For Arkansas, October usually is considered the best month to receive the vaccine. It takes about two weeks to build immunity.

So maybe you got the vaccine and still got the flu. What happened? The prediction of the strains that are likely to be present (which determines what strains the vaccine is made to defend against) is never perfect. Perhaps you were exposed to a strain that was not included in the vaccine. Also, through the season, the virus covered by the vaccine can mutate or change in a process known as antigenic drift. This results in the virus having different “fingerprints” that the immune system has not seen and, therefore, may not be able to protect against as effectively … if at all.

Why flu shots are important

So if the process is not perfect, why bother? Besides, the flu is just an inconvenience, right? Not exactly.

The flu may not be a big problem for your immune system, but it could be a very big threat to people you love. You get immunized to protect yourself, but also everyone around you. Small children and older adults, for example, do not have the ability to fight the flu that young, healthy adults might have. You don’t want to be the one to give the “gift” of the flu to your family or workmates.

The southern hemisphere has just completed winter, so we can get some idea from their experience what might be in store for us. Australia had four times the flu cases they had last year, so we need to buckle our seatbelts for a potentially more virulent season.

The bottom line: Get vaccinated.