Pneumococcal Vaccine Cuts Disease 90% in Kids with Sickle Cell

NASHVILLE, Tenn., May 2 -- The rate of invasive pneumococcal disease among children with sickle cell disease has fallen by more than 90% since the introduction of a new multivalent vaccine, according to researchers here.

The finding is another success story for the seven-valent pneumococcal conjugate vaccine, which has led to dramatic drops in invasive pneumococcal disease among children since it was introduced in 2000.

But the size of the decline in children with sickle cell disease -- who are highly susceptible to pneumococcal disease -- was unexpected, said Natasha Halasa, M.D., of Vanderbilt.

"I was not surprised that there was a decrease," Dr. Halasa said, "just surprised about the magnitude of the decrease."

The researchers compared the rates of invasive disease among people with sickle cell disease in parts of Tennessee from 1995 through 1999 and 2001 through 2004, they reported online in the June 1 issue of Clinical Infectious Diseases.

Dr. Halasa and colleagues identified 2,474 patients with sickle cell disease who were enrolled in TennCare, the state's managed health care program covering residents who are eligible for Medicaid benefits and those who are uninsured or uninsurable.

The study cohort included 2,026 (or 82% of the total with sickle cell disease) who lived in 11 counties that had active surveillance for invasive pneumococcal disease, which was defined as the presence of Streptococcus pneumoniae from at least one normally sterile body fluid.

During the study period, 37 patients with sickle cell disease also had invasive pneumococcal disease (no individual had more than one case) and the majority (56%) were children younger than five.

Analysis of the periods before and after the introduction of the vaccine showed:

• The rate of invasive pneumococcal disease fell from 3,630 to 335 cases per 100,000 person-years among children younger than two. The decline was 90.8%, which was statistically significant at P