In the US, serogroup B, C, and Y each cause approximately 1/3 of invasive meningococcal disease cases (IMD), including outbreaks in 2013-2015. Currently two MnACWY and two MnB vaccines are available in the US, where an age-based Category A recommendation was given for MnACWY vaccines (1 dose at 11 or 12 and booster dose at 16); whereas a Category B recommendation was given for MnB at age 16 to 23 years, with a preference for vaccination at 16-18 years. The difference in these recommendations is challenging; both strategies are designed to prevent IMD during the same period of risk. The objective is to explore potential public health impact of MnB vaccines if implemented using different recommendation strategies.
We constructed a discrete dynamic transmission model to simulate MnB carriage transmission over 30 years in the US population and from that calculate cases, sequelae, and deaths averted by vaccination using current age-specific disease incidence. Impact of vaccine implementation and uptake scenarios were assessed considering vaccination did or did not interrupt carriage acquisition. Base-case scenario assumed carriage protection and 29.6% uptake in age 16 (First observed uptake of MnACWY booster dose in this age group). A scenario using observed MnACWY uptake in 11 years old (77.8%) with a booster at age 16 (29.6%) was also assumed. Different scenarios with very low or high uptake rate of MnB at age 16 were also assessed.
Figure presents potential disease cases and deaths averted over 30 years of different MnB vaccination strategies and levels of uptake. Compared with base case, 400 more cases could be prevented if MnB recommendations mirrored MnACWY and achieved the same uptake. Sensitivity analysis shows the model is most sensitive to assumptions surrounding vaccine efficacy against carriage acquisition and uptake.
US adolescent vaccination rates are low but have been increasing over the past 11 years. Considering current low IMD incidence and improvements in adolescent vaccination, optimization of the MnB vaccination program could maximize IMD prevention.
Figure. Number of cases and deaths prevented with (white) and without (black) protection against carriage under potential vaccination scenarios
M. Xue, None
S. J. Snedecor, None