Dr. Jon Hallberg: questions about flu season 2013

Flu season has arrived, here in Minnesota and around the nation. Since late last year, the Minnesota Department of Health has classified influenza as "widespread" here in the state. Four hundred people were hospitalized for flu in the first week of the year, and 47 states nationwide are reporting similar outbreaks. There have also been questions about the effectiveness and availability of the flu vaccine.

MPR News' Tom Crann spoke with Dr. Jon Hallberg this week about the flu outbreak. Hallberg is a physician in family medicine at the University of Minnesota and medical director of the Mill City Clinic.

Tom Crann: Is this year actually noticeably different with flu outbreak?

Dr. Jon Hallberg: Not really. If we look historically, it's not that different, but we've had it easy for the last couple of years and I think that's why it seems like we're having an uptick in activity.

Crann: The [Centers for Disease Control and Prevention] has called it an epidemic. What should we know or think of when we hear that word being used? It worries people, I think.

Hallberg: It's such a charged phrase, but really what it means is that there's something going on, and this can be diabetes or violence or influenza, that can be reported as epidemic. And it's simply a rise from the baseline that you would expect of a certain thing happening. So we're seeing more cases than we might normally see at this time of year, so therefore it's an epidemic.

Crann: Seeing them earlier, too, right?

Hallberg: Yes, if we look historically at the last several decades, February is the peak month of activity, and it looks like ... it may be peaking now, a month earlier, but January's typically the second-busiest month, and March is the third-busiest.

Crann: Every year, they try to match the vaccine to the strains of flu. So tell us what we're dealing with this year and how well they did that.

Hallberg: There's three strains in this year. We have an old favorite - H1N1 is one of the three strains. We're not seeing very much of that at all happening. There's an A strain called H3N2, and about two-thirds of the cases out there match up with that. And then there's a B strain, a Wisconsin B strain, and about a third of the cases are that.

So as it turns out, actually it was a good match. They guessed correctly this year.

Crann: If you do get the flu and you're unlucky, are you done for the season then? Is that it?

Hallberg: If you've seen a particular strain, it is highly unlikely and maybe even impossible in many cases to get that same strain again, but we have more than one strain circulating. So theoretically, a person could get the flu, get influenza, but then get a different strain and it might feel exactly the same.

Crann: We always hear about people with compromised immune systems, maybe they have a chronic condition, or the elderly. Are they more susceptible?

Hallberg: Yes, sure. People at the extremes of life, those less than six months of age and those who are older, and it's hard to know what we mean by 'older' these days, their immune systems are inherently weaker. People who have chronic conditions, diseases like emphysema, severe asthma, congestive heart failure, they are also susceptible, in that if they get influenza, it can really throw those underlying conditions into a severe state.

Crann: For those populations with compromised immune systems, including the elderly, is the flu shot less effective?

Hallberg: Well certainly in the elderly it appears that it is. We're learning more and more about this, and frankly, this is a little embarrassing. The flu shot just isn't as good as it should be and needs to be, so that's certainly an area of focus is to really, really figure out a good flu shot for the elderly.

Crann: The flu shot is never 100 percent effective, right?

Hallberg: Right.

Crann: And this year we're hearing it is 62 percent effective. Tell us what that really means.

Hallberg: I think that we can't go into this thinking that if you get the shot, you have a two-thirds chance of it working for you. I think we have to assume that if you get it, it's going to work. I think a better way of thinking about this is if you immunize a hundred people, 62 percent of those people will be fully immunized, and it might not work in the other 38 percent. I think that's a better way of looking at that. And if you think about that, the people who are older and younger and immune-compromised and chronically ill, they're less likely perhaps to get the protection that they need, in a way.

Crann: But for those 62 people, they are fully immunized and protected, at least.

Hallberg: Well, yes, that's the way we should think about this ... So many people have spoken eloquently about the fact that we need a better vaccine. We need a better vaccine, but it's the best we've got, and therefore we've got to get it.

Crann: Is it ever too late to get a shot?

Hallberg: No. The flu season will kind of trickle off in March and maybe even into April a little bit. I think people have thought in the past that if they get it after Thanksgiving, it's too late, and that's simply not true. It takes about two weeks for it to become fully effective, and so we're looking (at) going into February for sure, so get it now.

Crann: We all know people who say, 'Well, I got the flu shot once, and then I got the flu. I felt awful after.' How often do you hear that?

Hallberg: All the time. If people tell me that they don't want to get the flu shot and they have a very convicted reason why, that's what they typically will tell me.

Crann: Any truth to it?

Hallberg: No. I tend to be very diplomatic about a lot of things, but this is one thing I just don't think we can be diplomatic about. It's a killed virus. There's no genetic material that is capable of replicating itself inside these immunizations. They check this before they go out the door.

What happens, and I think this explains it, is on the one hand, somebody might have actual influenza virus in them because they hadn't been immunized yet, and it takes several days to manifest, and so it seems like a causal relationship in a way. And now we know, too, that the vaccine simply isn't as effective as we'd thought, so they got the influenza but not from the vaccine.

(Interview edited and transcribed by MPR reporter Madeleine Baran)

Are you still planning to get a flu shot this year but aren't sure where to go? The Minnesota Department of Health's website has a "find a flu shot clinic" tool on its website where you can search for clinics with flu shots available.

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