Did the meningococcal vaccine reduce the incidence of disease?

Routine quadrivalent meningococcal conjugate (MenACWY) vaccination has been recommended for children aged 11 to 12 years following the US Advisory Committee on Immunization Practices recommendation in 2005. In 2010, a booster shot for teenagers aged 16 years was also recommended. A study in JAMA Pediatrics looks at how effective the recommendations were in reducing the incidence of meningococcal disease.¹

The investigators analyzed surveillance data to find all confirmed and probable cases of Neisseria meningitidis that had been reported to the National Notifiable Diseases Surveillance System from January 2000 to December 2017.

They found that the national incidence of meningococcal disease went from 0.61 cases per 100,000 population in the prevaccine era (2000-2005) to 0.15 cases per 100,000 population in the post-booster dose era (2011-2017). Overall the greatest percentage decline following vaccine introduction was seen in the serogroup C, W, and Y (CWY) combined in teenagers aged 11 to 15 years and 16 to 22 years. The incidence of serogroup CWY disease among teenagers aged 11 to 15 years decreased by 16.3% annually during the prevaccine period and 27.8% during the post-primary dose period. In adolescents aged 16 to 22 years, the incidence was cut by 10.6% annually in the post-primary dose period and 35.6% annually in the post-booster dose period. There were an estimated 222 cases of meningococcal disease caused by serogroup CWY that were avoided by vaccine in the evaluation period.

The researchers concluded that the rates of decline in meningococcal disease because of serogroup C, W, or Y was nearly 2-fold to 3-fold in the age groups studied. They did say that the MenACWY vaccine is not solely responsible for the decline in disease, but the study findings do suggest that it is linked to reduced disease rates.

Reference

1. Mbaeyi S, Pondo T, Blain A et al. Incidence of meningococcal disease before and after implementation of quadrivalent meningococcal conjugate vaccine in the United States. JAMA Pediatr. July 20, 2020. Epub ahed of print. doi:10.1001/jamapediatrics.2020.1990