Jessica R. MacNeil
New surveillance data demonstrated a steady decline in the incidence of meningococcal disease over the past 2 decades in the United States.
Substantial reductions in serogroups covered by the meningococcal conjugate vaccine (MenACWY) reflect the impact of the Advisory Committee on Immunization Practices’ (ACIP) 2005 recommendation to vaccinate individuals aged 11 to 18 years, and the committee’s 2010 recommendation to administer a booster dose to adolescents aged 16 years and older, according to Jessica R. MacNeil, MPH, epidemiologist at the CDC’s National Center for Immunization and Respiratory Diseases, and colleagues.
“Although it does not appear the adolescent meningococcal vaccination program has resulted in any significant indirect benefits in other age groups at this time, these data are the first to suggest an impact of the adolescent MenACWY program in reducing rates of serogroups A, C, W and Y among adolescents,” the researchers wrote in Clinical Infectious Diseases. “The largest declines in serogroups A, C, W and Y have been observed in younger adolescents, possibly due to high vaccination coverage in that age group.”
According to the researchers, 81.3% of adolescents aged 13 to 17 years have received at least one dose of the MenACWY vaccine by 2015. However, only 33.3% of patients aged 17 years received the booster dose. In addition to MenACWY, two serogroup B meningococcal (MenB) vaccines were approved in 2014 and 2015 for patients aged 10 to 25 years. Although the ACIP did not recommend routine vaccination with MenB vaccines, the committee encouraged individual clinical decision-making regarding MenB vaccines in adolescents and young adults aged 16 to 23 years.
“This recommendation for individual clinical decision-making was made, in part, because of the current low incidence of meningococcal disease,” MacNeil and colleagues noted.
To investigate trends in meningococcal disease incidence, the researchers examined data on confirmed and probable cases that were identified from 2006 to 2015 through the National Notifiable Diseases Surveillance System (NNDSS) as well as confirmed cases identified from 1996 to 2015 through the Active Bacterial Core (ABC) surveillance system.
According to NNDSS data, 7,924 cases of meningococcal disease occurred in the U.S. from 2006 to 2015 — nearly 15% of which were fatal. The average annual incidence was 0.26 cases per 100,000 population. Oregon had the highest incidence, with 0.79 cases per 100,000 population. Cases were most commonly reported in infants aged younger than 1 year (2.45 cases per 100,000), and fatalities mostly occurred among adults aged 85 years and older (28%). Based on available information, 35.8% of cases were serogroup B, 28.5% were serogroup Y, 22.8% were serogroup C, 6.8% were serogroup W and 6.1% belonged to other serogroups.
The overall national incidence declined 70.8%, from 0.40 cases per 100,000 in 2006 to 0.12 cases per 100,000 in 2015. There was a 76% decline in serogroups covered by the MenACWY vaccine in patients aged 11 to 20 years. Smaller reductions in serogroup B were also observed in this population.
ABC surveillance data demonstrated steady reductions in meningococcal disease incidence among all age groups from 1996 to 2015. The largest decline was among infants aged younger than 1 year, which decreased 93%, from 11.04 cases per 100,000 population to 0.73 cases per 100,000 population. The incidence of serogroup B declined 80%, serogroup C declined 97% and serogroup Y declined 95%. Other serogroups remained fairly stable, according to the researchers. – by Stephanie Viguers
Disclosures: The authors report no relevant financial disclosures.