Background: Meningococcal disease is a rare but severe and potentially deadly infection caused by Neisseria meningitidis. Two types of vaccines are licensed in the US, quadrivalent vaccines protecting against serogroups A, C, W, Y (MenACWY) and vaccines protecting against serogroup B (MenB). The Centers for Disease Control and Prevention (CDC) recommends routine MenACWY vaccination for 11- to 12-year-olds, with a booster at 16. The MenB vaccine is recommended for 16- to 23-year-olds based on shared-clinical decision-making.
Objectives: This retrospective ecological study aims to evaluate the spatial and social factors associated with county-level stocking rates for both MenACWY and MenB vaccines from 2016 to 2019. We hypothesize that social deprivation, measured by the CDC’s social vulnerability index (SVI), impacts vaccine stocking with generally lower rates of vaccine stocking in areas with greater deprivation in socioeconomic status (SES).
Methods: We compiled a single county-level data set for all fifty states and DC. Vaccine stocking data were sourced from IQVIA (private market) as well as the CDC’s Vaccines for Children program (public market). SVI was calculated using the 2015-2019 American Community Survey and is measured from 0 to 100. Additional county-level measures included availability of pediatricians and primary care providers, proportion of children with public insurance and without insurance, Department of Defense installations, rurality, and tribal lands. We also included indicators for state-level MenACWY and MenB requirements. Our model selection approach used Lagrange Multiplier tests, which indicated that spatial error multivariable regression models were appropriate for these data.
Results: For MenACWY’s private market, a unit increase in SES deprivation is associated with a 0.953 decrease in stocking rates (p = .001). A ten-point increase would, therefore, equate to about 10 fewer doses per 1,000 children. For MenB’s private market, SES has a similar effect, with a -0.368 (p = 0.028) change per unit increase. In the public market, the relationship between SES and stocking is reversed. An increase in SES deprivation is associated with greater MenACWY stocking (beta = 0.632, p = .015), while the association is not significant for MenB (beta = -0.100, p = 0.369).
Conclusions: SVI’s SES measure impacts stocking by vaccine and market, with increasing socioeconomic inequality associated with decreased meningococcal vaccine stocking in the private market after controlling for other factors. For MenACWY’s public market, our findings demonstrate the positive impact of the VFC program on community-level access in deprived areas, while the relationship for MenB needs further research.
