Before introduction of 7-valent pneumococcal conjugate vaccine (PCV7), Alaska Native children and adults experienced high rates of invasive pneumococcal disease (IPD) compared with non–Native Alaskans. Rosalyn J. Singleton, M.D., M.P.H., of the Centers for Disease Control and Prevention, Anchorage, and colleagues evaluated IPD in Alaska children for evidence of the emergence of nonvaccine serotype disease from 1995 till 2006.

The authors found that in the three years after introduction of PCV7 (2001-2003), IPD decreased 67 percent among Alaska Native children younger than 2 years and 61 percent in non–Native Alaska children in the same age group. Between 2001-2003 and 2004-2006, IPD rates did not change for non–Native Alaska children younger than 2 years.

However they increased 82 percent among Alaska Native children so that the overall IPD reduction in these children was only 39 percent during 2004-2006 compared to before vaccine introduction. Since 2004, the invasive pneumococcal disease rate caused by nonvaccine serotypes has increased 140 percent compared with the prevaccine period. During the same period, there was a 96 percent decrease in heptavalent vaccine serotype disease.

"For Alaska Native children there now exists a substantially elevated risk for IPD from serotypes not contained in PCV7. The demonstration of replacement IPD in Alaska Native children may signify a limit to the usefulness of the currently available vaccine and emphasizes the importance of development of extended valency vaccines or vaccines not dependent on serotype-specific prevention. These data also highlight the value of continued surveillance and other epidemiological investigations to monitor the effects of pneumococcal vaccines," the authors of the article which is published in JAMA conclude.; Source: JAMA and Archives Journals