Meningococcal disease is an infectious bacterial disease associated with a high mortality rate if left untreated. The vaccine for the disease – quadrivalent meningococcal conjugate (MenACWY) vaccine – has been developed, but its efficacy is not well documented. The objective of this study is to determine the incidence of meningococcal disease before and after the implementation of the MenACWY vaccine in the USA.

This is a cohort study that included all the cases of the meningococcal disease between January 1, 2000, and December 31, 2017. The participants were given the MenACWY vaccine, and the primary outcome of the study was the incidence of the meningococcal disease using Poisson segmented regression analysis.

The national incidence of meningococcal disease insuring the pre-vaccine period was 0.61 cases per 100,000 population, which declined to 0.15 cases per 100,000 population during the post-vaccine period. The serogroup (CWY) demonstrated the greatest percentage decline: 16.3% during the pre-vaccine period and 27.8% during the post-vaccine period. A total of 222 cases of meningococcal disease due to serogroup CWY were averted during the evaluation period.

The findings suggested that the introduction of primary MenACWY dose resulted in a decline in the incidence of meningococcal disease due to serogroup CWY.