- Home>
- Specialty Care>
- Infectious Diseases>
- Summary and Comment
Replacement of Pneumococcal Serotypes After PCV7 Vaccination
Since the introduction of the pneumococcal conjugate vaccine, initial reductions in invasive pneumococcal infections among Alaska Native children have been eroded by an increase in nonvaccine-serotype infections.
The introduction of the heptavalent pneumococcal conjugate vaccine (PCV7) in the U.S. in 2000 was followed by a sharp reduction in the rate of invasive pneumococcal disease (IPD) in young children (see Journal Watch Infectious Diseases May 23 2003). This vaccine contains just 7 of >90 known serotypes, but these 7 serotypes have been estimated to cause 80% to 85% of IPD in children.
To measure the effects of PCV7 vaccination, researchers conducted longitudinal population-based laboratory surveillance from 1995 through 2006 for IPD among Alaska Native children <2 years old, a group known to have a high IPD rate. Routine PCV7 immunization began in 2001 in this population. More than 90% of these children receive 
3 doses of PCV7 — a rate significantly higher than that for non-Hispanic white Alaska children or for the overall U.S. population of the same age.
In 2001–2003, the PCV7-serotype IPD rate was 92% lower — and the overall IPD rate was 67% lower — than in 1995–2000. In 2004–2006, however, the overall IPD rate increased by 82% compared with 2001–2003. This increase was associated with a 130% rise in the rate of non–PCV7-serotype IPD. Serotype 19A accounted for 28% of the nonvaccine-serotype cases in 2004–2006.
Comment: These findings demonstrate replacement of PCV7 serotypes with nonvaccine serotypes, particularly 19A, which also has increased in other populations. Such figures, from an especially vulnerable population, demonstrate the need for continued surveillance and for development of pneumococcal vaccines with additional serotypes.
— Robert S. Baltimore, MD
Published in Journal Watch Infectious Diseases May 2, 2007
Citation(s):
Singleton RJ et al. Invasive pneumococcal disease caused by nonvaccine serotypes among Alaska native children with high levels of 7-valent pneumococcal conjugate vaccine coverage. JAMA 2007 Apr 25; 297:1784-92.
- Original article (Subscription may be required)
- Medline abstract (Free)