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Vaccine is futile vs. new strains

CHICAGO -- While a new vaccine has all but eradicated common causes of pneumonia, meningitis, and ear infections in children, new strains of bacteria not covered by the vaccine have emerged, US researchers said yesterday.

Since the introduction of Wyeth's wildly successful vaccine Prevnar in 2000, doctors have been waiting and watching for the arrival of replacement bacteria that could undo its progress.

Now they may have found them.

Researchers from the US Centers for Disease Control and Prevention have noted an increase in the rates of bacterial infections not covered by the current pneumococcal vaccine among native children in Alaska.

"People are on top of it. It is not unexpected, but it is important," Dr. Katherine Poehling of Brenner Children's Hospital at Wake Forest University in Winston-Salem, N.C., said in a telephone interview.

The vaccine, also called heptavalent pneumococcal conjugate vaccine or PCV7, is marketed as Prevnar in the United States and Canada and as Prevenar elsewhere in the world. Given initially at ages 2, 4, and 6 months, it protects children from bacteria that often cause ear infections and drug-resistant pneumonia.

"Because of the surveillance, we are seeing it and we can act in a timely manner and maintain the benefits that we've seen," said Poehling, who wrote a commentary on the study published in the Journal of the American Medical Association.

The CDC's Dr. Rosalyn Singleton and colleagues studied pneumococcal infections such as pneumonia, meningitis, or blood infections known as bacteremia that occurred from 1995 to 2006.

They found that in the three years after the introduction of Prevnar, from 2001 through 2003, these diseases fell by 67 percent among native Alaskan children younger than age 2 and 61 percent in non-native children.

Between 2001 and 2003 and 2004 and 2006, these infection rates remained stable in non native Alaskan children younger than 2, but jumped 82 percent among Alaska native children, who are more prone to the infections.

Since 2004, diseases caused by strains of bacteria not covered by the vaccine have risen by 140 percent compared with the prevaccine period.

During the same period, diseases caused by the vaccinecovered strains fell by 96 percent.