November 1999
BETHESDA, Md. - The Food and Drug Administration (FDA) Vaccines and Related Biological Products Advisory Committee recently recommended approval for the seven-valent pneumococcal conjugate vaccine (Prevenar, Wyeth Lederle Vaccines).
The advisory panel looked at two specific issues: efficacy and safety. In its efficacy vote, the panel was unanimous in finding that the data provided sufficient evidence of efficacy against invasive disease, namely bacteremia and meningitis.
For safety, the panel voted 10-1 that the data showed the vaccine to be safe. The lone dissenter was Barbara Loe-Fisher, a non-physician member of the panel.
Doug Pratt, MD, PhD, from the FDA, said that the efficacy vote was based on data presented from a three-year trial from Northern California Kaiser Permanente led by Henry Shinefield, MD, and Steven Black, MD. Data was also presented from a trial conducted in Finland.
More than 38,000 children were enrolled in the three-year, randomized, double-blind study at Kaiser. Half the participants received pneumococcal conjugate vaccine and half received a control vaccine. Each child was given doses at 2, 4 and 6 months of age, with a fourth dose at 12-15 months.
Children also received the diphtheria-tetanus-pertussis/Haemophilus influenzae type b (DTP/Hib) combination at 2, 4, 6 and 24 months of age; the inactivated polio vaccine (IPV, IPOL, Pasteur Mérieux Connaught) at 7, 12 and 24 months; and measles-mumps-rubella (MMR, M-M-R II, Merck) at 18 months of age.
Shinefield and Black found that the vaccine was 97% efficacious against bacteremia and bacterial meningitis.
The seven strains included in the vaccine cause about 85% of the pneumococcal disease reported in the United States. Aside from bacterial meningitis and bacteremia, additional childhood infections commonly caused by Streptococcus pneumoniae include otitis media and pneumonia. The study indicated the pneumococcal conjugate vaccine resulted in a 73% reduction in pneumonia with a chest X-ray pattern showing consolidation, a 33% reduction in pneumonia with an X-ray showing any infection, and an 11% reduction in clinical visits with a diagnosis of pneumonia.
It was also shown to reduce physician visits for otitis media (OM) and reduce the need for tympanostomy tubes in those who suffer from frequent ear infections.
Researchers found a slight interference with the level of protection to one of the pertussis antigens and also to IPV. Dixie Snider, MD, MPH, associate director for science at the Centers for Disease Control and Prevention (CDC), said that he did not think the interference would lead to increased susceptibility to disease. However, he recommended that this trend be monitored. The panel agreed, recommending post-marketing studies to monitor long-term safety and to find out more about the vaccine's effect on OM.
The randomized, controlled Finnish trial indicated the vaccine was effective against both culture-confirmed serotype-specific acute otitis media (AOM) and culture-confirmed pneumococcal OM.
In related news, the CDC's Advisory Committee on Immunization Practices (ACIP) recommended the pneumococcal conjugate vaccine for routine use in all healthy children age 5 and younger, with priority use in specific populations. The recommendation was contingent upon licensure of the S. pneumoniae vaccine and an additional review if any new safety or efficacy data become available and when vaccine cost is known. Look for a more detailed explanation of the ACIP recommendations in our next issue.
Although the FDA does not have to approve a product based on the advisory committee's recommendation, it usually does.
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