Invasive pneumococcal disease reduced after vaccine introduction

ATLANTA — The use of the pneumococcal conjugate vaccine (Prevnar, Wyeth) is associated with a significant reduction in invasive pneumococcal disease in vaccinated children, according to a recent study.

The study, published recently in The New England Journal of Medicine, also demonstrated that the overall incidence of invasive disease caused by penicillin-resistant Streptococcus pneumoniae bacteria substantially declined since the vaccine’s introduction.

Approved by the FDA in February 2000, the vaccine remains the first and only vaccine approved to help prevent invasive pneumococcal disease in infants and toddlers. The routine schedule is vaccination at 2, 4, 6 and 12 to 15 months of age.

The study, led by Cynthia G. Whitney, MD, and other researchers from the CDC, documented a steep decrease in the incidence of disease in children younger than 2 years of age from the 1998 baseline period through 2001.

The researchers examined population-based data from the Active Bacterial Core Surveillance of the CDC to evaluate changes in the burden of invasive disease defined by isolation of S. pneumoniae from a normally sterile site. The researchers assessed trends using data from seven geographic areas from 1998 through 2001.

The rate of invasive disease dropped from an average of 24.3 cases per 100,000 people in 1998 and 1999 to 17.3 per 100,000 in 2001. The largest decline was in children younger than age 2. In that group, the rate of disease was 69% lower in 2001 than the baseline rate (59 cases per 100,000 vs. 188.0 per 100,000).

The rate of disease caused by vaccine and vaccine serotypes declined by 78% and 50% respectively.

CDC researchers also noted that disease rates fell for adults, dropping 32% for adults 20 to 39 years of age, 8% for those between 40 and 64 years of age, and 18% for those ages 65 and older.

Overall surveillance showed a 78% decline in disease in children younger than age 2 caused by the strains targeted by the vaccine.

The researchers also found a 35% disease reduction caused by strains that were not susceptible to penicillin among children younger than 2 years of age.

Geno Germano, an executive vice president at Wyeth said, “We are excited about the role that Prevnar has played in helping the CDC’s ‘Healthy People 2010’ initiative accomplish one of its objectives.”

For more information:

• Whitney CG, Farley MM, Hadler J, et al. Decline in invasive pneumococcal disease after the introduction of protein-polysaccharide conjugate vaccine. N Engl J Med. 2003;348(18):1737-1746.

• Dr. Whitney has no direct financial interest in the products mentioned in this article, nor is she a paid consultant for any companies mentioned.