There were several questions about the use of the new conjugate pneumococcal vaccine (Prevnar, Wyeth Lederle Vaccines) by pediatricians attending the Second Annual Infectious Diseases in Children Symposium West, held about one week after the vaccine was licensed. The meeting took place in Marina Del Rey, Calif.
Below is a portion of the question-and-answer session between Henry Shinefield, MD, one of the main investigators of the vaccine, and Philip A. Brunell, MD, chief medical editor of Infectious Diseases in Children.
Philip A. Brunell: Where are we as far as licensure and recommendations for use?
Henry Shinefield: The vaccine has been licensed for use against invasive disease. It has not been licensed for ear infections or pneumonia. The data from our study will be combined with the data from the Finnish study and will be revisited by the Food and Drug Administration from the standpoint of licensing the vaccine for otitis media (OM) and perhaps, pneumonia, as well.
The proposed regimens for the vaccine: for children 0-6 months of age, four doses; for children 7-11 months, three doses; 11-24 months, two doses; and for those 24-59 months, one dose.
Unfortunately, this vaccine is expensive. At this time the Advisory Committee on Immunization Practices (ACIP) recommends that all children up to 59 months of age be immunized with a provision that includes a prioritized list of those who should receive vaccine if resources are limited.
Specifically the ACIP "recommends" the vaccine for infant immunization, catch-up to age <23 months, and children 24-59 months in high-risk groups, such as those with sickle-cell disease, anatomic/function aspenia, HIV, chronic illness or immunocompromising conditions, as well as Alaska Natives, American Indians and African-Americans.
The ACIP recommendations state that the vaccine "should be considered" for 24- to 59-month-olds who attend group child care (>4 hours/week with at least two unrelated children), are socially or economically disadvantaged, and had frequent or complicated acute otitis media in the previous year.
Let me add one more important factor in the use and expectations regarding the new pneumococcal conjugate vaccine. After our initial presentation of the striking effect of this vaccine in invasive disease, the media and news reports were dominated with the cry of the "development of a new vaccine against ear disease." Not a word was said about the effect of this vaccine against ear infections in our presentation. Still, all the news was about "success against ear infections."
The greatest barrier to the successful implementation of the use of this vaccine will be the promotion or expectations regarding ear infections. It has a modest effect against ear disease; somewhat more in children with severe repeated ear infections. However, ear disease is caused by many organisms other than the pneumococcus. Repeat ear infections must be expected even after complete immunization with the conjugate vaccine. This must be made clear to parents. This vaccine is the first step in the prevention of this common troublesome pediatric problem.
Brunell: What about kids who have already received the pneumococcal polysaccharide vaccine?
Shinefield: The conjugate vaccine can be used with those kids. Children, for example, who have sickl- cell anemia and have received one shot of the 23-valent polysaccharide vaccine should get a single dose of the conjugate vaccine. In these and other immunocompromised children who receive conjugate vaccine, it can be boosted later with the 23-valent vaccine.
Brunell: Are we going to have new serotypes emerge and cause disease if we eliminate the seven serotypes in the vaccine?
Shinefield: There is evidence from data in South Africa and Israel that immunization with the conjugate vaccine reduces oropharyngeal carriage of vaccine strains. This may be important in producing herd immunity, which will contribute to the elimination of diseases such as has been seen with Haemophilus influenzae type b.
However, there appears to be either recolonization or appearance of previously inhibited nonvaccine strains that take the place of vaccine stains.
Fortunately, at this point, they are not the serotypes that cause invasive or significant disease. Can this change? In the laboratory, the ability of strains to acquire different serotypes has been demonstrated. It will be necessary to follow colonization and the clinical care status of vaccinees and nonvaccinees to understand all the implications of vaccination. We are going to follow 60,000 vaccinated children long term to evaluate these changes.
Brunell: Would you stop penicillin prophylaxis in a child with sickle-cell disease who has received the conjugate vaccine?
Shinefield: No, because there still may be problems with the other serotypes.
Brunell: Is there any place for this vaccine in adult immunization?
Shinefield: At present, no. There are limited data. The vaccine only covers seven serotypes. There are more types that affect adults in the 23-valent vaccine. The current antibody production has not been studied enough to recommend any change in adults.
Brunell: What happens when you license the nine- and 11-valent conjuggate vaccines? Will the kids who have received the seven-valent vaccine have to be revaccinated?
Shinefield: I doubt that. In the United States, hopefully, there will be enough coverage with the seven-valent vaccine so those children will not have to be revaccinated with the nine- and 11-valent vaccine.
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