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ACIP clarifies pediatric pneumococcal vaccine recommendations
Concerns regarding combined vaccine schedules and revaccination intervals were discussed.
ATLANTA— The Advisory Committee on Immunization Practices voted in favor of wording changes that will effect 23-valent pneumococcal polysaccharide vaccine use in high-risk children aged younger than 10 years.
The committee’s new recommendations are specific to children who are immunocompromised, have sickle cell disease, or have functional or anatomic asplenia, and state that a single revaccination interval of five years is sufficient for administering a second dose of the vaccine to children aged 2 years and older in these populations, who were previously vaccinated with the seven-valent pneumococcal (PCV7, Prevnar, Wyeth) conjugate vaccine. This simplifies previous recommendations that suggested that second doses be administered between three and five years, depending on the child’s projected immunological response to the vaccine at different ages.
The changes reflect concerns regarding potential hyperresponsiveness that may occur when children are subsequently exposed to pneumococcal antigens after receiving 23-valent pneumococcal polysaccharide vaccine (PPV23, Pneumovax23, Merck) according to Pekka Nuorti, MD, and CDC epidemiologist, who presented the working group’s activities at the ACIP meeting last month.
“Immunocompromised persons, persons with sickle cell disease or functional or anatomic asplenia are at highest risk for serious pneumococcal infection and may have a rapid decline in pneumococcal antibody levels after receiving PPV23,” Nuorti told Infectious Diseases in Children.
A previous recommendation stated that physicians could consider administering a second dose of PPV23 three to five years following the administration of a first dose pneumococcal vaccine.
However, this was based on immunologic data from the 1980s collected using outdated antibody assays that lacked sensitivity and specificity, Nuorti said.
Although data on immunogenicity and clinical efficacy after revaccination with PPV23 remain limited, Nuorti said that a longer interval between administering multiple vaccine doses may reduce hyporesponsiveness in patients recieving these vaccines.
Furthermore, older children may have a better immunologic response, Nuorti added, citing data from previously published studies by Vernacchio et al and Rao et al.
Despite these concerns, data on administering PPV23 to healthy children who have already received either PPV23 or PCV7 indicate an excellent booster response, according to Nuorti. CDC officials said they hope that revaccination recommendations can target the serotypes only contained in PPV23, but Nuorti warned that efficacy data to support this hypothesis do not exist. – by Nicole Blazek
For more information:
- Nuorti P. Revaccination with PPSV23 in high risk children who have previously received PCV7. Presented at: the Advisory Committee on Immunization Practices Meeting; Oct. 22-23, 2008; Atlanta.