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
“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
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
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
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.
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