Unpredictability of flu season should be motivation to get shot

Oct 4, 2013

Every year at this time, public health officials encourage Americans to get a flu vaccine, but the majority of people choose not to have a flu shot. Lorraine Rapp and Linda Lowen, hosts of WRVO's health and wellness show Take Care, recently spoke with Dr. Joseph Bresee of the Centers for Disease Control about how the vaccine works to prevent the flu, and why the CDC recommends it.

Lorraine Rapp: What sort of flu season is expected this year?

Dr. Joseph Bresee: Well you never actually know. One thing we know about flu is that it’s unpredictable each year. So some years, we’ll have mild years, some years we’ll have severe years, and you can’t really predict it. That’s why we have everybody get vaccinated before flu season starts, because once it starts, it’ll be severe or mild, but you really don’t know ahead of time.

Linda Lowen: What are the factors that will influence whether a flu season is severe or mild?

Dr. Bresee: I think that some of the things that clearly affect how severe a season’s going to be are the types of viruses that circulate, some flu seasons tend to cause more disease and deaths than other flu viruses. The attack rate by age-- viruses that attack older people tend to result in more hospitalizations and deaths than viruses that tend to affect younger people for instance. But a lot of the things that affect how severe or mild a flu season is going to be are really hard to predict.

Lorraine: How does the flu shot work to prevent, or help them prevent getting the flu?

Dr. Bresee: To start with, remember that there are two types of flu vaccines. One is an injectable vaccine, the sort of classic vaccine you inject into somebody’s arm, and the other is a live vaccine, which you spray up somebody’s nose. The injectable vaccine, the way it works, is you inject pieces of a flu virus, usually the outer coating of the virus, and what that does, it allows the body’s immune system to detect the virus and the proteins of the virus, and develop antibodies against them. So once you have those antibodies, when you’re infected later in the season with a real flu virus, you already have antibodies against that very flu virus that can act quickly to rid yourself of the disease or give yourself a milder illness than you otherwise would have. The live vaccine works a little differently. It’s live, so it actually grows like a real flu virus, but its weakened flu virus. And so, it doesn’t cause disease, but because it grows in your nose and your throat, it allows your body to develop a very robust immune response to it, just like it would to a natural infection to flu.

Lorraine: How long between injection, or how long in between the nasal spray, and somebody’s ability to fight off the flu should they be exposed?

Dr. Bresee: It really does take about two weeks. And this is important because as we think about when to vaccinate people, we want to make sure that people get vaccinated early enough in the fall, before flu hits their community, so they develop good protection before they experience flu in the wild.

Linda: So when does flu activity usually begin, and when can we expect to see it peak?

Dr. Bresee: Generally speaking, we start to see activity around now, in the fall time—October and November. The peaks usually occur somewhere between January and March in the United States, and then you get a tail off into April and May.

Lorraine: What percent of the population chooses to get a flu shot every year?

Dr. Bresee: The most recent data we have is from last year, and last year 45 percent of the US population got a flu vaccine, and that’s an all-time high, and gratifying because it’s slightly higher than the year before and we’re trending the right way. But the other side of looking at it is that more than half the people in the United States didn’t get a flu vaccine last year, and that’s a shame, and we need to do a better job in getting people to get the vaccine.

More of this interview can be heard on "Take Care," WRVO's health and wellness show Sundays at 6:30 p.m.  Support for this story comes from the Health Foundation for Western and Central New York.