This October, the Food and Drug Administration is expected to approve the 13-valent pneumococcal conjugate vaccine (PCV13) for use in adults aged 50 years and older, but before it becomes widely used for that age group, more research is needed on immune response in adults, the herd effect produced by vaccinating children, and the overall preventable disease burden among adults.
That was the conclusion of the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices, which discussed whether they should expand the recommendations for the vaccine at a recent meeting. Currently, PCV13 is recommended for all children aged 2-59 months and up to 71 months, if underlying conditions put the child at higher risk.
"Licensure will be based on immunogenicity data only, comparing the immune response of PCV13 to PPSV23," said Dr. Michael Marcy, chair of the pneumococcal vaccines working group. Published immunogenicity studies have shown noninferior immune responses in adults after one dose of PCV13, compared to PPSV23 for all common serotypes.
"The models show that PCV13 in adults could be highly cost effective," said Tamara Pilishvili, who is a CDC representative on the pneumococcal vaccines working group. However, the cost-effectiveness model assumes indirect effects of PCV13 on nonbacteremic pneumonia. If PCV13 proved ineffective against nonbacteremic pneumonia, there would be less support to recommend the vaccine for use in adults.
Factors favoring the use of PCV13 in adults include the potential to reduce a large burden of adult disease, improving on the limited acceptance of PPSV23 in the adult population, and capitalizing on the success of the PCV13 vaccine in children, Ms. Pilishvili said.
Factors weighing against the use of PCV13 in adults include the potential for the herd effects from vaccinating children to curtail the overall impact of vaccinating the adult population. Few data back the efficacy of the vaccine to prevent pneumonia in adults. There also are challenges and costs are involved in attempting to expand vaccine coverage in the adult population, she noted.
The working group will evaluate new data as they become available, including results from a randomized, controlled trial of the efficacy of PCV13 against community-acquired pneumonia in adults aged 65 years and older from the Study Evaluating a 13-Valent Pneumococcal Conjugate Vaccine in Adults (CAPITA). Additional immunogenicity data will also be analyzed from a phase III of adults aged 18-49 years, as well as adults at increased risk for pneumococcal disease.
The proposed indication for PCV13 is for the prevention of disease caused by Streptococcus pneumoniae serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F.
Ms. Pilishvili and Dr. Marcy reported that they had no financial conflicts of interest.