US incidence of meningococcal disease highest among infants
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Incidence of meningococcal disease was at historic lows in the United States from 2006 through 2012 yet it remained greatest among infants aged younger than 1 year.
Jessica R. MacNeil, MPH, of the CDC, and colleagues calculated incidence rates for Neisseria meningitidis during that period using data from an active, population- and laboratory-based surveillance system, Active Bacterial Core surveillance. The surveillance area included Connecticut, Georgia, Maryland, Minnesota, New Mexico and Oregon, plus counties within California, Colorado, New York and Tennessee.
There were 127 cases of meningococcal disease among infants aged younger than 1 year in the surveillance area, with an average annual incidence of 3.3 cases per 100,000 infants. Incidence ranged from 1.11 cases (Connecticut) to 10.45 cases (Oregon) per 100,000 infants. Oregon’s incidence rate was due to hyperendemic serogroup B disease, according to the researchers.
Sixty-four percent of disease isolates were serogroup B, 16% were serogroup Y, 12% were serogroup C, 6% were serogroup W, and 2% were nongroupable.
From 2006 to 2011, there were an estimated 113 cases of culture-confirmed meningococcal disease annually among children aged younger than 1 year, an overall incidence of 2.74 per 100,000 infants.
“Approximately 23% of infant meningococcal disease cases could be prevented with a serogroup C and Y vaccine if protection was achieved by age 4 months; a vaccine that protects against serogroup B by 4 months of age would have the potential to prevent about 37% of infant cases,” the researchers wrote. “A combined serogroup B, C, and Y vaccine would have the potential to prevent up to 63% of infant meningococcal disease cases in the United States.”
Further analysis of case report forms indicated 19.5% of cases had a history of current breast-feeding; 26% attended day care, and 62% had a smoker in their household.
“Because the largest burden of disease in <1-year-olds occurs in children 0 through 6 months of age, many will be too young to have received the minimum two or three doses of vaccine that likely will be needed to prevent disease,” the investigators concluded. “Consideration of other programmatic interventions may be necessary to protect these youngest infants because direct protection of most infants with these vaccines is not possible.”
Disclosure: Harrison reports financial ties with GlaxoSmithKline, Merck, Novartis, Pfizer and Sanofi Pasteur. Schaffner reports financial ties with Dynavax, Merck, Pfizer and Sanofi Pasteur. The other researchers report no relevant financial disclosures.