The flu and you

Jan 16, 2020

According to the Centers for Disease Control and Prevention, flu activity in the United States is high and is expected to continue that way for several weeks. It is currently below epidemic thresholds but it is definitely worth watching. If you haven’t yet, you still have time to get a flu vaccine and prepare your home for any family members who may still get the flu.

Kinds of fu

Influenza is primarily a respiratory illness caused by a multitude of viruses under two general categories (A and B). 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. Currently, the B/Victoria strain is predominant nationally, which is unusual for this time of year. This year’s vaccine focused on the following strains: A/Brisbane (in Australia), A/Kansas, B/Colorado and B/Phuket (in Thailand). While the current vaccine isn’t a perfect match to the predominant strain, it may still give some protection, and it is possible that the predominant strain will shift during flu season to one that does match the vaccine.

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.

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 bottom line: Get vaccinated.

You can learn more about the current flu situation at the CDC website.