Original Paper

Safety and efficacy of the seven-valent pneumococcal conjugate vaccine: evidence from Northern California

Abstract. Pneumococcal disease remains a significant cause of morbidity among young children. A large-scale efficacy trial in the Northern California Kaiser Permanente system (the KP trial) demonstrated that a seven-valent conjugate vaccine (PCV) is safe and immunogenic in young children and effective in preventing both invasive pneumococcal disease caused by vaccine serotypes (97.4% efficacy) and episodes of otitis media (7.0% efficacy). Since the publication of the results of the KP trial in 2000, we have performed an additional analysis on the safety, immunogenicity, and efficacy of the vaccine in low birth weight (LBW) and preterm (PT) infants, and have examined the efficacy of the vaccine during 1 year of wide-scale post-licensure use. The vaccine was at least as immunogenic in LBW and PT infants as in normal-weight, full-term infants and was 100% effective, although the LBW and PT infants had higher rates of adverse events such as redness and swelling. LBW and PT infants receiving pneumococcal vaccine also had higher rates of adverse events, such as hives, than those receiving control meningococcal vaccine, but these reactions were not severe. When the PCV was used in the general population, the efficacy remained high and there was no corresponding increase in disease caused by nonvaccine serotypes. There was also evidence that vaccine administration led to herd immunity. Febrile illness was the only adverse event seen more frequently after vaccine administration than during a control period. Conclusion: the seven-valent conjugate vaccine is safe and effective for use in the general population.

Keywords. seven-valent conjugate vaccine - efficacy - trial - immunogenecity

Abbreviations. DTaP diphtheria-tetanus-toxoid acellular pertussis DTwP diphtheria-tetanus-toxoid whole cell pertussis FT full-term IPD invasive pneumococcal disease ITT intent-to-treat KP Kaiser Permanente LBW low birth weight NBW normal birth weight PCV seven-valent conjugate vaccine PT preterm

E-mail: steve.black@kp.org Phone: +1-510-2677534