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Invasive pneumococcal disease decreased after introduction of PCV13

IDSA 49th Annual Meeting

BOSTON — In the first year after the introduction of the 13-valent pneumococcal conjugate vaccine, a cohort of US hospitals showed significant declines in invasive pneumococcal disease, according to findings presented here.

“In the first full year after the vaccine was introduced, we saw about a 35% decline in the number of invasive cases,” Sheldon L. Kaplan, MD, of Baylor College of Medicine and Texas Children’s Hospital in Houston, told Infectious Diseases in Children.

Kaplan’s research, which was presented at the IDSA 49th Annual Meeting, highlighted a 75% reduction in invasive pneumococcal infections in children after the 7-valent pneumococcal conjugate vaccine (PCV7; Prevnar, Pfizer) was introduced in 2000. In 2005, prevalence of non-PCV7 serotypes of invasive pneumococcal disease — particularly 19A — had increased. The current study reports on early data for invasive pneumococcal disease in children after the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13; Prevnar 13, Pfizer) in February 2010.

“After PCV13, we saw a 45% decline in serotype 19A,” Kaplan said. “This is a very encouraging result.”

The researchers prospectively identified children with invasive pneumococcal disease from eight children’s hospitals in the United States since 1993. Isolates were collected, and the proportion of those isolates with penicillin minimum inhibitory concentrations of 2 mcg/mL or more was eligible for analysis. The current data are for the period from July 1, 2007, to June 30, 2011.

Besides declines in serotype 19A, substantial decreases in incidence of serotypes 7F, 3 and 6C were observed during the 4-year period. “Serotype 6A is a new component, but 6A was pretty much gone already because of cross-protection from PCV7,” Kaplan said. “But now, 6C has emerged.”

In 2010-2011, serogroup 15 (n=9; 15A-2, 15B-3, 15C-4) was also common, according to the results. A significant decrease in isolates with penicillin MIC of 2 mcg/mL or more was observed during the study duration (P=.003).

Forty-three percent of children had underlying conditions in 2010-2011. In that same period, 42 children had received one or more doses of PCV13; 27 children had received one dose, nine had received two doses and six had received three doses.

Sixteen children had PCV13-serotype isolates, 12 of which were serotype 19A. Underlying conditions were observed in six of the 16 children with PCV13 isolates. Half of the six children who had received three PCV13 doses had serotype 33F.

The researchers also concluded that penicillin resistance decreased. “However, we did observe that serotype 19A is really driving the antibiotic resistance,” Kaplan said.

Kaplan urged ongoing surveillance of invasive pneumococcal disease incidence among children.

Disclosure: Dr. Kaplan reports being an investigator for and receiving research support from Pfizer.

For more information:

• Kaplan SL. #LB-1. Presented at: IDSA 49th Annual Meeting; Oct. 20-23, 2011; Boston.

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