Pregnant Women Targeted For H1N1 Vaccine Trials
ROBERT SIEGEL, host:
From NPR News, this is ALL THINGS CONSIDERED. I'm Robert Siegel.
MELISSA BLOCK, host:
And I'm Melissa Block.
The first trial of a new HIN1 swine flu vaccine in pregnant women gets underway this week. The vaccine will be tested on 120 women in their second and third trimesters.
The trial is being run by the National Institute of Allergy and Infectious Diseases, and director Anthony Fauci joins us to talk about it. Welcome to the program.
Dr. ANTHONY FAUCI (Director, National Institute of Allergies and Infectious Diseases): It's good to be here.
BLOCK: We've known that pregnant women are one of the target groups considered at higher risk for HIN1. What is the purpose of this trial? What are you trying to show?
Dr. FAUCI: Well, there are a couple of things. There are some safety studies, which is in the short-term. But as important is to make sure we get the right dose and the right number of doses. So the trial is going to test the standard dose that you generally give with seasonal flu. And twice that dose, given either as a single dose or as two doses separated by 21 days. So we're trying to find out the best way to develop a vaccination program for pregnant women.
BLOCK: You mentioned that one of the goals is to check safety issues. If I'm a pregnant woman, what would convince me that it's safe to be part of this vaccine trial?
Dr. FAUCI: Well, you know, the thing that many people don't appreciate is that this vaccine is really what we call a strain change from the seasonal vaccine, which we have decades of experience with.
BLOCK: Seasonal flu.
Dr. FAUCI: Yeah, seasonal flu vaccine. The seasonal flu vaccine is made by the same companies that are making this HIN1 pandemic flu vaccine. They are the same companies, the same processes, the same types of materials. So there's a track record of really quite good safety for many, many years in a variety of groups, including pregnant women.
BLOCK: You know, Dr. Fauci, I'm just thinking, you know, women - pregnant women are leery of just so many things during their pregnancy: the food they eat, the vaccines they're thinking about getting. I just wonder how you confront people's fears and possible effects since much is unknown about this virus.
Dr. FAUCI: Okay. That's an excellent question - a quite reasonable question. Whenever you talk about any kind of intervention in a pharmaceutical product of any sort, what you do is you balance what we call the risk and the benefit. Pregnant women are at a considerably higher risk for the complications of this pandemic HIN1 flu or of any influenza. In fact, of the deaths that have occurred from serious HIN1 influenza among people in this country, six percent of the deaths are among pregnant women, even though pregnant women comprise only one percent of the population.
BLOCK: Dr. Fauci, why is the risk of serious complications higher in this group of pregnant women?
Dr. FAUCI: Well, the risk of complications is generally two-fold. When women are pregnant their immune system becomes compromised, because the fetus is representing the genes of both the mother and the father. So there's a degree of what we call foreignness to the fetus, so that there would be a tendency to reject something that's foreign.
But Mother Nature, what it does, it allows the immune system of a pregnant woman to adapt itself to be suppressed during the time of pregnancy so that you don't have an immunological rejection of the fetus. That's one of the reasons why.
The other is, particularly in the latter time of the pregnancy, when the mass of the fetus in the abdomen creates a difficulty with the free movement of air in the lungs of women. And women, as you know, during the latter part of pregnancy do not have as good respiratory capacity as someone who is not pregnant. So there are two reasons from a physiological standpoint why women might be and are in reality at a greater risk for the complications of influenza.
BLOCK: Dr. Fauci, thank you very much.
Dr. FAUCI: You're quite welcome.
BLOCK: That's Dr. Anthony Fauci. He's director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health.
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