CDC News Conference Transcript

Update on Current Influenza Season

November 17, 2003

DR. GERBERDING: Thank you very much for taking time to join us today.

What I'm going to do at this press briefing is to provide an update on the influenza outbreak this year.

We have some information that's been accumulated through our many efforts to conduct surveillance for this problem on an ongoing basis, and some of that news is very concerning.

In particular, we're very concerned that the flu season has had an earlier onset than we've seen in many years, and we are seeing some parts of the country that are having very high levels of widespread flu infection.

You can see here on my map of the United States [graphic posted at www.cdc.gov/media “Weekly Influenza Activity Estimates; as of November 8, 2003.”] Texas is really standing out as a state where there's widespread involvement of influenza. States in the dark purple, actually, right now, just Colorado is the state that's having a fairly high degree of activity, and then the states in the lighter phase of purple where there's local activity but not as quite widespread as it is in the regional perspective in Colorado or in Texas.

Some other states are not showing activity or at least have not yet reported activity to us, but it's still very early in the flu season.

I'm bringing this up today for a couple of reasons.

One is because there's a lot of concern about the early onset and the need for immunization, and second, because our early information from the evaluation of the strains involved in these problems suggest that a high proportion of flu this year is of a strain called H3N2. This is a type of influenza A. The strain that we're most concerned about right now is a strain that's slightly different from the strain that is in the vaccine. This is what is known as the "drift" strain.

This year's influenza vaccine for the northern hemisphere contains material that will protect against three strains of flu, H3N2 Panama, H1N1 New Caledonia, and Influenza B Hong Kong.

The strain that we're most concerned about, that is a drift version of H3N2 is called the Fujian strain. It's very similar, it's just drifted a little bit from the Panama strain, and our animal studies suggest that the vaccine will provide cross-protection against this strain. In the past this has happened. It's a very common thing. As flu strains gradually evolve in people, we don't always have exactly have the same strain as a vaccine that is circulating in the community and our experience so far, historically, has been that whatever the drift is, that the vaccine will still provide some cross-protection.

So we're optimistic that would be the case this year but of course we'll be watching that very carefully and we'll know more as the flu season evolves.

The point is that people need to get their flu shot. This is the time for Americans to really step up to the plate and get vaccinated against influenza, especially because this could be a worse-than-usual flu season and especially because we have this particular strain circulating and in some previous situations H3N2 strains have been associated with perhaps more severe disease.

So let me just review, one more time, who should have a flu shot.

Bottom line is that anyone who wants a flu shot should get a flu shot. But there are some people who are at especially high risk for serious influenza and let me just remind you how serious influenza can really be.

In this country, where we have over 114,000 hospitalizations usually from influenza, we have 36,000 people die from the complications of influenza. So this is very serious. People who are over age 50 are recommended to get the vaccine because, in part, people over this age group are at higher risk for the conditions that increase the probability of more serious influenza disease.

People with heart disorders, people with lung disorders, people with kidney disorders, people with any condition that causes the compromise in their immunity should be vaccinated, and certainly everyone over age 65 should be vaccinated against influenza.

We're also encouraging immunization of children between ages of six months and 23 months.

The reason for this is that the evidence indicates that children in those age groups are at increased risk for hospitalization from the complications of flu and if they get vaccinated, they're much, much less likely to need to be in the hospital. So those are individuals that we are also encouraging immunization for.

There's one very important group of people who we are strongly encouraging get vaccinated this year and those people are health care workers.

We know that the environment of health care is a place where people get admitted, or come to receive treatment when they have influenza. Influenza can be transmitted from health care worker to patient in those contexts. Health care workers can also acquire influenza from their patients.

While they may not be at high risk for the serious complications, they can develop serious complications and they can also bring that influenza home to their families or others who live in their households.

So we are working very hard with the medical community, distributing information such as this, such as a very important tool kit that contains a lot of information for clinicians, to help them encourage and motivate their own vaccination as well as getting their patients vaccinated.

We know from previous experience that immunization rates in health care workers are not optimal. From several different sources, we know that, on average, less than 50 percent of the health care workers who should be vaccinated actually receive their vaccine.

I just got mine, and I'm encouraging all the health care workers I know, who are in contact with patients, to receive their flu vaccine.

But it is not just a good idea. I think it's really a responsibility for health care workers to provide that level of extra protection to themselves, their patients, and their families.

We will be working even harder and more aggressively with the health care community to try to encourage this.

The last very important point about influenza is that the flu shot is very safe. The only contraindication to receiving the flu vaccine is an allergy to eggs because the vaccine is made in egg products. It's a very, very safe vaccine and it absolutely does not give you the flu.

There's a lot of confusing information out about the flu shot side effects, but there's absolutely no chance of getting influenza from the flu shot because it's made from a product that is killed, not a living vaccine.

And so the main complication people experience from the flu shot is a sore arm and that's one that I think we all agree would be a minor price to pay for the incredible benefit that this vaccine provides, not only ourselves but also the people we care about.

Let me stop there and take some questions.

A question here in the room?

If not, let me take the first question from the phone, please.

MODERATOR: Mr. Daniel DeNoon [ph] from WebMD. Your line is now open.

QUESTION: Hello. Thank you, Dr. Gerberding. I have kind of a two-part question.

One is the Fujian drift variant, as you put it, the H3N2, I think last reported, there were four deaths from children in the UK.

Does this mean this is a much more dangerous and lethal strain, and could you comment on that and what makes it so dangerous.

And secondly, could you go over the evidence suggesting that the Panama strain in the vaccine does in fact offer protection.

DR. GERBERDING: Thank you.

You know, all flu strains can cause serious disease, but in the past we have seen perhaps a more severe presentation of strains involving the H3N2 characteristic.

This is not anything we know for sure, looking prospectively with the Fujian strain, but the early information suggests that we need to be concerned about that and that's part of the reason why we're really pushing the vaccine.

This is not a pandemic at this point in time. I don't want to confuse people. This is just an earlier onset of flu season in the United States as well as some European countries than we've seen earlier, and we will be working very hard to get out in front of this in every way that we can.

The evidence about the cross-protection from the vaccine, which is again the H3N2 Panama, compared to the H3N2 Fujian strain, is based, first, on animal experiments.

This is the way we typically look for the capacity of one antibody to effect similar strain of virus, and the animal studies that have been done are very promising, that there is cross-protection between these two strains. That's what we've seen in previous years, where that's been proven in retrospect to the case clinically as well.

So there is that very promising laboratory perspective on it.

Second, and I think a very strong argument here, is what we've learned from the many years where we've been in this situation. It's always a challenge to make sure that we get a perfect match between what's in the vaccine and what circulates in the community.

In fact, in almost all years, by the end of flu season, some new strain or some new drift species will show up, and so by the end of the flu season we don't always have the same match that we do. So this is a very common challenge that we face here.

But what we can say is from all of our past experience, when we've had a drift evolve, and it's not included in the vaccine, that we still are able to identify effectiveness of the vaccine, so there is cross-protection at the population level, and we will of course do everything we can to evaluate that in this particular situation.

But we're optimistic, and that's why we're saying please get your flu shot. All this discussion about drift strain is important in trying to achieve the very best match, and it's important because the vaccine that's made for the Southern Hemisphere, that will be initiating immunization for their flu season, will contain the H3N2 Fujian strain.

But the vaccine that is available to us right now in the Northern Hemisphere does not. We still believe the existing vaccine will protect against that Fujian strain.

So please get your flu vaccine.

QUESTION: I wonder about now, in the context of SARS, and what that will mean for the health care system, people thinking maybe that they have symptoms of SARS and having the flu, or vice-versa.

DR. GERBERDING: Thank you. You know, with any respiratory illness, for a given person, at the beginning of the illness it's very difficult to tell from clinical information what is causing it.

But in flu season we know that there's a higher chance that it's either influenza or one of the other respiratory viruses.

Right now, SARS has not emerged in any corner of the world. We're obviously very vigilant about that. We're doing everything we can to be prepared for it.

But today, if someone develops a flu-like illness and goes to the health care facility, it should be assumed to be influenza or some other common respiratory virus and not SARS.

We are also, at least in this country, anticipating that if SARS emerges, it's most likely going to emerge in travelers or in people who've been in parts of the world where it has emerged, and as I said, so far we have no evidence that it has emerged anywhere.

Another question from the phone, please.

MODERATOR: Miriam Falco from CNN, your line is open.

QUESTION: Hi, Dr. Gerberding, thanks for doing this. A two-part question. Number one, is this the most serious early onset since 1976? Would you describe it as "serious"?

DR. GERBERDING: This is early onset from the standpoint that we have more cases, particularly in Texas, where we see it's fairly widespread, spread of flu. But we have had many years where flu has started early and peaked earlier than average.

So it's a little too early in the game to say whether or not this portends the worst flu season we've had in a long time, and we're putting the word out now because the early signs are that at least in some parts of the country it's a serious problem and now is a chance to jump in there and prevent it from getting any worse.

Did you have a second part to your question, Miriam?

[No response.]

DR. GERBERDING: It doesn't sound like it.

OPERATOR: Miriam Falco, your line is open.

QUESTION: I'm done. Thank you.

DR. GERBERDING: Okay. Thanks. She always has two parts to her question, so I was waiting for the second part.

Is there another question from here in the room?

[No response.]

DR. GERBERDING: Great. I'll take a phone question.

OPERATOR: Anita Manning from USA Today, your line is open.

QUESTION: Hi. Can you hear me all right?

DR. GERBERDING: Yes, I can. I can hear your dogs, also.

[Laughter.]

DR. GERBERDING: She hung up. Let's take another phone question.

OPERATOR: Merrill from WTAA, your line is open.

QUESTION: WTAE in Pittsburgh. We have a couple of questions here concerning the hepatitis A outbreak in Beaver County, Pennsylvania. What can you tell us what the CDC has established so far from its investigation and testing, the focus of the CDC in tracing it right now and whether or not it is related to the previous outbreaks in Tennessee, North Carolina or Georgia.

DR. GERBERDING: Thank you. CDC is working with the State of Pennsylvania to provide technical assistance as the state works to solve this particular outbreak problem. Let me just say that we are very concerned and understand how difficult this is for the people who are involved in the outbreak. There are more than 500 cases known to the State Health Department at this point in time, and that's a very big worry for our community. So we are there, and we're doing everything we can to put this whole issue to rest.

CDC has several investigators on the ground who are assisting in the investigation. We have participated in similar outbreaks in Georgia, North Carolina, and Tennessee already this year. The three earlier outbreaks in the Southern states were linked to green onions or scallions. And the FDA, and CDC and the involved states are working to trace back the source of those scallions and to try to identify areas where transmission may have occurred or to find the ultimate reason why those green onions were contaminated.

In Pennsylvania, I don't think that we have confirmed the food source that is the cause of the problem, but the early indications certainly suggest that a food source, again, is the most likely source, as opposed to an infected individual, and the case investigations, where we compare people who have the hepatitis infection with those who had similar exposure, but didn't develop hepatitis, those studies are in progress, and they're going as fast as can be expected, given the very large number of people involved.

So we expect to be able to identify the most likely cause of the outbreak in Pennsylvania, just as this was done in the other three states, but I think the emphasis is on preventing further transmission of hepatitis. So we have alerted health departments all over the country. We're studying at CDC the specific details of the virus strains because we want to see how genetically similar they are. This gives us some clues as to whether we're dealing with one source or a cluster of sources or widespread sources of the problem.

In addition, the immunization program that's been stepped up in Pennsylvania to provide gamma globulin to contacts of individuals, as well as some people who were exposed in the restaurant, is going extremely well. That immunization program will go a long way to preventing any of the people who have been infected at the first exposure from transmitting this to their close household contacts or to others.

So it's a work in progress, and I know everyone wishes that we had all of the answers, but in this case, the good science that's going on is going to take a little bit of time. This is a very large problem, and I think the collaboration between FDA, CDC and the states are certainly doing a terrific job, and the other agencies involved. We'll get to the bottom of it as quickly as we can.

Is there another question here?

QUESTION: I know you are encouraging people to get their flu shots early. Is there a date that you'd say that you're [inaudible], and also the second is where do we [audio break]?

DR. GERBERDING: In terms of getting flu shots, right now is the best time to get a flu shot, if you haven't gotten one already, and we encourage people to get flu shots throughout flu season, which usually lasts through March, but the sooner the better, obviously. And if influenza has not peaked yet in your community, the time is right for a flu shot. So rather than waiting, do it now so that you're protected when it arrives in the community, if it's not already there.

The West Nile situation is that we are not seeing new cases, the onset of new cases at this late part of the year, but we did end the season with the recognition that there was West Nile Virus in Southern California, and usually the pattern has been, when you see it emerging in one new area of the country at the end of the season, that's likely to be a hot spot for transmission the following year.

So obviously we'll be working very closely with the State of California and making sure that we're doing everything that we can to try to be out in front of this from the standpoint of vector control as well as preparing people to take the steps to protect themselves.

Let's have a telephone question, please.

OPERATOR: John Lauerman from Bloomberg News, your line is now open.

QUESTION: Thanks for taking my question. How much earlier are we; that is, is there a way to express in weeks or quantify how much earlier we are, as a follow-up?

DR. GERBERDING: This is a very variable sort of onset. In different years, we see the beginning of the season start early or later, and we see the peak start early or later. I think I have some comments here that I can just follow up with you on later, but this is not out of bounds. The heaviest influenza activity was in December in 4 of the last 26 influenza seasons--January in 6 years, February in 11 years, March in 3 years, April in 1 year and May in 1 year. So there's a broad distribution of when we see the peak of influenza. But for Texas at least, we already see widespread influenza, and so that's on the earlier time frame from what we would normally expect, and that's why we're here today was to sound the alarm, so to speak, so that people can prudently get to the clinician and get their flu shots taken care of.

I may remind you that the reimbursement rate for influenza vaccination has improved this year, so the cost of flu shots should not be a barrier to getting the shot, and people need to do that.

Another telephone question, please.

OPERATOR: Anita Manning from USA Today, you may ask your question.

QUESTION: Thank you. I'm sorry about that. My phone went crazy before.

Dr. Gerberding, when you say a "more severe flu season," do you mean that people will get sicker or that more people will get sick? What exactly do you mean? And, generally, like in the last few years, we've had a couple of very mild seasons, and so I guess you're predicting that this year will be worse than the last couple of years. How do you know that, except for the fact that it's starting a little sooner?

DR. GERBERDING: First of all, we don't have a crystal ball, and so we have to be prepared for the fact that our predictions may not turn out to be exactly as we're presenting them here today, but we do know that we're seeing many states with significant influenza activity in October and early November. So that's one marker of severity, much more widespread disease early on in the season, and the fact that a significant proportion of the 55 virus strains that we characterized so far, 84 percent of them are the H3N2 drip strain.

And because in past years, H3N2 influenza A has typically been associated with higher rates of hospitalization and higher mortality than some of the other flu strains, that is part of the reason why we're worried about this being a more severe year.

So earlier onset, perhaps a signal of more widespread infection, but because it's also involving a particular strain, we are worried about the possibility that there will be greater consequences in the population this year.

All of those facts are subject to revision as we go forward and actually make the measurements, and the one thing that would make all of the difference in the world is that if we really did see the kind of immunization response that we need, we could nip this problem in the bud and really see a much less severe flu season than we're predicting right now. So there's still time to have an impact on this, and we need to take those steps.

I'll take a phone question, please.

OPERATOR: Larry Altman of the New York Times, your line is open.

QUESTION: Julie, I know the biggest problem in preventive medicine is you can't prove what you've prevented. But how would you know if the immunization had been effective and prevented a more serious season this year or, conversely, that the vaccine wasn't as protective as you're hoping that it would be at the moment?

DR. GERBERDING: One way, unfortunately, of assessing the benefit of the vaccine is because not everybody does get their flu shot, and so you can see what happens in groups of people who were not compliant or did not take advantage of this potentially life-saving intervention and compare their rates of hospitalization and deaths from respiratory illness to groups of people that had high immunization rates.

Sometimes there are also outbreaks in institutional settings that help us assess the efficacy of a vaccine. As you know, those studies are tough to do because of the large sample size required, but, nevertheless, we get a lot of clues from that way.

I think what we ultimately will be able to do is a very comprehensive retrospective using data from the Medicare utilization records and so forth as a typical way for us to learn about the value of a vaccine program in retrospect. Unfortunately, to conduct a large-scale, prospective assessment of efficacy or effectiveness is very challenging, but we are working with the Department of Health and Human Services and FDA to see whether or not such an assessment might be feasible in the future.

Does that answer your question, Larry?

[No response.]

DR. GERBERDING: Is he off the line or satisfied?

QUESTION: I mean, one of the problems is that it's hard to prove what you've prevented in preventive medicine. I mean, that's just a given rule.

DR. GERBERDING: Yes, you're absolutely right, and that's part of why we try to have the surveillance system not just focusing on the situation here domestically, but also on an international front. I'd be very happy if we see no or low rates of influenza this year compared to other years, and that may be because our vaccine program is successful. It could also just be because we are wrong in our predictions, but either way we win. So we'll hope that turns out to be the case.

Let's take one more phone question, please.

OPERATOR: Lee Bowman from Scripps Howard News, you may ask your--your line is open.

QUESTION: Thanks, Dr. Gerberding. Just a follow-up of Larry's question.

We know that there's virtually record amounts of vaccine available this year, but do you have any indication so far this year real time of what the level of vaccination activity has been so far?

And, secondly, as far as the community surveillance network that you have, does that track who's gotten vaccinated and who hasn't?

DR. GERBERDING: The information about the specific vaccine coverage is a little premature. We don't have that coming in, in the same real-time way that we do for some other diseases, but we have done an assessment of a sentinel group of hospitals to try to get a sense of where they are. The National Foundation for Infectious Diseases has also hosted a conference earlier this month to try to understand how the vaccine was progressing in the health care environment.

The party line is people have the impression that we're doing better this year than last year, but we don't have the data to back that up at this point in time. We look forward to getting some solid numbers around that as we go forward.

I think I'll stop here. Again, thank you for your attention. This is such an important health issue, and we really appreciate the interest of the press in supporting the influenza program because we have to get this word out in every way that we can.

Thank you for your time.

[Whereupon, the press briefing was concluded.] 

Listen to the telebriefing

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