MenACWY program associated with reduced invasive meningococcal disease among adolescentsLatest revision | Image Credit: © Generative AI - © Generative AI - stock.adobe.com.

Results from a decision analytical model of the entire population of the United States from 2001 to 2021 revealed the MenACWY vaccination program in the country was associated with a reduced burden of meningococcal disease. Results demonstrated that incidence of invasive meningococcal disease among individuals aged 11 to 23 years would have been at least 59% higher without vaccination.

Background

In 2005, the United States implemented routine immunization of adolescents with a quadrivalent conjugate vaccine, MenACWY, to prevent IMD, a disease that is associated with severe disease, most frequently meningitis or sepsis. A booster dose was recommended in late 2010 to address vaccine waning immunity concerns.

"Although the MenACWY vaccine has been effective in mitigating the risk of IMD, assessing the population-level association of vaccination with IMD burden has proven challenging, in part due to a decreasing trend in IMD incidence among different age groups that began 8 years before the introduction of the vaccine program," wrote the JAMA Network Open study authors, led by Thomas Shin, MA, Health Economics and Outcomes Research, Sanofi, New Jersey.

Authors noted that an evaluation of the association between MenACWY vaccination and the incidence of IMD in the United States demonstrated the primary and booster doses "accelerated the decreasing rates of IMD by up to 3-fold in the vaccinated adolescent age groups."

"In this study, we evaluated the direct association of MenACWY vaccination with the incidence of IMD among adolescents and young adults 11 to 23 years of age," wrote the authors. "Using a bayesian hierarchical Poisson regression approach, we estimated the age-specific incidence rates of IMD among unvaccinated individuals by fitting the model to national incidence data for serogroups C, W, and Y spanning the years 2001 to 2021 with a parameter associated with the vaccination status of individuals with reported IMD cases."

Investigators simulated a counterfactual scenario in the absence of vaccination, enabling them to estimate the number of IMD cases prevented by vaccination and to quantify incidence rates among adolescents and young adults "in the hypothetical absence of vaccination."

Study details and results

Data for the model was provided by the Centers for Disease Control and Prevention. The model included the entire age-stratified US population and was fitted to national incidence data for serogroups C, W, and Y from January 1, 2001, to December 31, 2021, with stratification by vaccination status for IMD cases, according to the study.

Among the entire population in the United States with stratification for ages younger than, 1, 2 to 4, 5 to 10, 11 to 15, 16 to 23, 24 to 49, 50 to 64, and 65 years or older, the investigative team estimated that vaccine failures occurred in 95 individuals from 2005 to 2021. Of these, 18 were vaccinated with more than 1 dose of MenACWY. Based on the bayesian model and simulating the counterfactural scenario, it was estimated that vaccination among those aged 11 to 15 years averted 172 cases of IMD (95% bayesian credible intervals [CrIs), 85-345). For individuals aged 16 to 23 years during the same period, it was estimated that 328 cases were averted (95% CrI, 164-646).

Without vaccination, according to results, the cumulative incidence of IMD in these respective age groups "would have been at least 59% higher than reported over the same period with vaccination. Based on the counterfactual scenario, the mean incidence rate of IMD per 100,000 population for combined serogroups C, W, and Y among adolescents aged 11 to 15 years would have been 0.17 (95% CrI, 0.08-0.35) from 2006 to 2010, 0.08 (95% CrI, 0.04-0.17) from 2011 to 2017, and 0.05 (95% CrI, 0.03-0.11) from 2018 to 2021 in the absence of vaccination," per study results.

Using case fatality rates of unvaccinated individuals from national data, vaccination averted an estimated 16 deaths among individuals aged 11 to 15 years (95% CrI, 8-31), and 38 deaths among those aged 16 to 23 years (95% CrI, 19-75).

Conclusion

In the analytical model study, vaccination against serogroups A, C, W, and Y of N meningitidis was associated with a reduced burden of IMD in young adults and adolescents in the United States.

The authors concluded that continued vaccination coverage is required to avoid health concerns.

"Given the severity of the disease and its potential lifetime sequelae, any decrease in vaccine uptake or in the level of protection within the US population could become a public health concern, especially during the high-risk period of late adolescence and early adulthood," they concluded.

Reference:

Shin T, Wells CR, Shoukat A, et al. Quadrivalent Conjugate Vaccine and Invasive Meningococcal Disease in US Adolescents and Young Adults. JAMA Netw Open. 2024;7(11):e2443551. doi:10.1001/jamanetworkopen.2024.43551