Meningococcal vaccination: a discussion with all adolescents, whether college-bound or not

ABSTRACT

Introduction: Adolescents and young adults are the primary reservoirs and transmitters of meningococci. In the US, meningococcal serogroup B (MenB) disease predominates over A, C, W, and Y; ACIP-recommended MenACWY and MenB vaccines are available. We investigated invasive meningococcal disease (IMD) burden and vaccination among non-college adolescents.

Methods: IMD incidence by college attendance status and vaccination rates were analyzed using publicly available surveillance data.

Results: 64/158 IMD cases occurred in non-college 18–24-year-olds during 2015–2017. Among non-college cases, the MenACWY vaccination rates were 38%–57% vs 90%–100% among college cases when vaccination status was known; MenB vaccination was 0% vs 0%–7%, respectively. In 2018, 17.2% of all 17-year-olds received ≥1 dose of multidose MenB vaccines; ≤50% completed the series.

Conclusion: Meningococcal vaccination is emphasized for college-bound adolescents, but non-college adolescents bear much of the disease burden. Low vaccine receipt preserves their risk, underscoring the need to protect all adolescents through vaccination.

KEYWORDS:

• Meningococcal serogroup B
• adolescents
• prevention and control
• epidemiology
• vaccination
• college

1. Introduction

Although uncommon, invasive meningococcal disease (IMD) caused by the bacterium Neisseria meningitidis is unpredictable and serious [1,2]. Infection may be difficult to diagnose and can progress rapidly to death; up to 19% of survivors experience permanent disability. Adolescents and young adults have the highest nasopharyngeal carriage rates (~1 in 4 can be asymptomatic carriers); they are considered the principal transmitters of meningococci via respiratory droplets and secretions through their typical behaviors, including kissing, social mixing, and frequent close contact [2].

In the United States, IMD is caused by serogroups B, C, W, and Y; serogroup B (MenB) now predominates among adolescents and young adults aged 16–23 years, accounting for 69.6% (48/69) of cases in 2017 [3]. IMD due to serogroups A, B, C, W, and Y is vaccine-preventable. Quadrivalent polysaccharide conjugate vaccines for serogroups A, C, W and Y (MenACWY) are recommended by the Advisory Committee on Immunization Practices (ACIP) for routine vaccination of healthy adolescents at ages 11 and 16 years [4]. MenB vaccination is routinely recommended (previously called ‘Category A’) for individuals aged ≥10 years at increased risk of IMD due to underlying conditions (e.g., immune or complement deficiencies), or exposure due to outbreaks or occupation (e.g., microbiologists) [5]. ACIP also recommends MenB vaccination for healthy 16–23-year-olds (16–18 years preferred) under shared clinical decision-making (previously called ‘Category B’) [5,6].

The MenB vaccination recommendation for shared clinical decision-making was the first non-routine ACIP recommendation for an entire age group (i.e., adolescents) [7]. Pediatricians and family practice physicians have since reported confusion regarding the specifics and implementation of this recommendation. Additionally, providers are more likely to recommend MenB vaccination to college-bound individuals in this age group [8]. When establishing the 2015 recommendation, the ACIP concluded that disease incidence in college students was similar to or lower than that in all individuals aged 18–23 years and those not attending college [5]; however, enhanced meningococcal surveillance data from 2014 to 2016 showed that college students have 3.5 times greater relative risk for MenB disease versus non-college adolescents [9].

We analyzed 3 years (2015–2017) of IMD epidemiology among US individuals aged 18–24 years by college status and vaccine coverage to determine the optimal approach to exercising the existing shared clinical decision-making recommendation for MenB vaccination.

2. Methods

We analyzed Enhanced Meningococcal Disease Surveillance (EMDS) data from the Centers for Disease Control and Prevention (CDC) from 2015 to 2017 [3], focusing on 18–24-year-olds by college attendance status. For statistical analyses, the college (10.95 million) and non-college (13.64 million) populations surveyed were estimated using the number of IMD cases and incidence rate (IR; cases per 100,000 individuals) in 2015; P-values comparing average annual IRs between college and non-college individuals across the 3-year surveillance period were calculated using Poisson regression. Vaccination coverage was examined using the 2018 CDC National Immunization Survey–Teen [10]. As an analysis of publicly available data, this study was exempt from human subjects committee review.

3. Results

Between 2015 and 2017, a total of 158 IMD cases occurred in individuals aged 18–24 years for whom college status was known [3]: 64/158 cases (40.5%; 95% CI [32.8%, 48.6%]) occurred among those not attending college and 94/158 cases (59.5%) occurred among college students (Figure 1(a) [3]). MenB caused the highest number of cases (96): 74 and 22 cases in the groups attending and not attending college, respectively (Figure 1(b) [3]); serogroups C, W, and Y collectively caused 10 cases among college students and 25 cases among those not attending college. The average annual number of cases and IRs were significantly different between college vs non-college individuals for both all IMD (31.33 cases, IR = 0.29 vs 21.33 cases, IR = 0.16 [P= 0.0314]) and MenB (24.7 cases, IR = 0.23 vs 7.33 cases, IR = 0.05 [P= 0.0007]).

Figure 1. Meningococcal disease dynamics among adolescents and young adults by college attendance status, and immunization delivery.

(a) Number of IMD cases in US individuals 18–24 years of age by college attendance status during 2015–2017. Data are from Enhanced Meningococcal Disease Surveillance Reports 2015–2017 (available at: https://www.cdc.gov/meningococcal/surveillance/index.html#enhanced-reports) [3]. (b) Serogroup distribution of IMD cases by college attendance status during 2015–2017. Data are from Enhanced Meningococcal Disease Surveillance Reports 2015–2017 [3]. (c) 2018 immunization rates of US adolescents 13–17 years of age for various vaccines. Data are from Walker et al. MMWR Morb Mortal Wkly Rep. 2019;68:718–723 [10]. (d) MenACWY and MenB vaccination status of IMD cases in US individuals 18–24 years of age with known vaccination history by college attendance status in 2015–2017. Data are from Enhanced Meningococcal Disease Surveillance Reports 2015–2017 [3]. HPV = human papillomavirus vaccine; IMD = invasive meningococcal disease; MenACWY = meningococcal serogroups A, C, W, and Y vaccine; MenB = meningococcal serogroup B vaccine; Tdap = tetanus, diphtheria, and acellular pertussis vaccine.^aIn adolescents 17 years of age.

Examining coverage rates for meningococcal vaccines compared with other adolescent vaccines among US 13–17-year-olds showed that the tetanus, diphtheria, and acellular pertussis (Tdap) vaccine had the highest coverage rate (88.9%; Figure 1(c) [10]) and 51.1% of individuals were up-to-date for the human papillomavirus (HPV) vaccine series recommended at age 11–12 years [4,10]. MenACWY vaccine coverage for ≥1 dose (recommended at age 11 years [4]) was 86.6%; coverage for ≥2 doses was 50.8% (booster dose recommended at age 16 years [4]) [10]. In contrast, the MenB vaccination rate, 3 years after the 2015 ACIP recommendations for vaccination at ages 16–18 years [5], was 17.2% for ≥1 dose of a multidose series among 17-year-olds; ≤50% of those who start actually complete a MenB vaccine series [11].

The EMDS system collects data on the vaccination status of IMD cases [3]; however, these data are not complete. That said, between 2015 and 2017, among IMD cases with vaccination records, MenACWY vaccine receipt in the group not attending college was substantially lower (38–57%) than that in the college group (90–100%). With the exception of 2016 (7% in the college group), no cases in either group had received MenB vaccination (Figure 1(d) [3]).

4. Discussion

Meningococcal immunization of college-bound adolescents is a major US public health focus. However, EMDS data show that individuals who are not college-bound bear a substantial percentage (40.5%, 95% CI [32.8%, 48.6%]) of the IMD burden [3]. Among 18–24-year-olds, 22.9% of MenB cases and 71.4% of serogroup C, W, and Y cases combined occurred among those not attending college. Among college students, MenB disease has been increasing over time and has caused all 14 college outbreaks between 2011 and March 2019 [12], while serogroups C, W, and Y disease incidence has remained low and stable [3]. Among those not attending college, IMD incidence has remained relatively stable across these serogroups.

These data are consistent with observations that nasopharyngeal meningococcal carriage peaks at age 19 years [2]. Individuals of this age are key transmitters of meningococci via sharing saliva through food and utensils, smoking, frequent kissing, and residing in close-contact environments [2]. Importantly, these behaviors are common to all adolescents and young adults rather than restricted to college students, 68.3% of IMD cases in this age group are sporadic and not outbreak-associated [9], and meningococcal carriage rates can be similar between colleges that have experienced an outbreak and those that have not [13]. These data collectively suggest that both behavior (i.e. sharing secretions) and biology (i.e. carriage) enable transmission of meningococci to adolescents irrespective of college attendance.

Fewer opportunities exist to immunize adolescents compared with younger children because adolescents are generally healthy and compliance with recommended annual well visits declines steadily after age 15 years [14]. Meningococcal vaccine coverage (MenB ≥1 dose, 17.2%; MenACWY, 50.8%) is lower than that of other vaccines administered as part of the CDC’s 16-year-old platform (Figure 1(c)) [4,10]. Finally, EMDS data show that fewer IMD cases in those not attending versus attending college had previously been vaccinated with MenACWY (38–57% vs 90–100%); MenB vaccination among IMD cases was extremely low in both groups (0–7%) [3].

In 2017, MenB disease accounted for 69.6% of all IMD among US adolescents and young adults [3]. In contrast, serogroups C, W, and Y disease rates have remained low, likely in part due to the MenACWY vaccination program and highlighting the strength of the age-based routine ACIP recommendation.

MenACWY vaccination appears to be the strongest predictor of MenB vaccine receipt. Analysis of >45,000 electronic health records of 16–23-year-olds from a regional pediatric care network reported a significant association between MenACWY receipt and MenB vaccine series completion [15]. Similarly, a study using national insurance claims data reported that MenB vaccination was most highly associated with MenACWY receipt, followed by HPV vaccine receipt [16]. Additional recent US studies have reported this same association along the continuum of MenB vaccine awareness, intent to vaccinate, and receipt. A nationally representative survey of 619 parents of 16–19-year-olds demonstrated that awareness of MenB vaccines and interest in potentially vaccinating was significantly higher among those aware of MenACWY vaccines [17]. A regional cross-sectional survey of 445 parents of adolescents found that an equivalent percentage of parents were willing to vaccinate their teens with MenACWY and MenB vaccines (58.6% and 55.1%, respectively) and were seeking advice from their provider (79.6% and 81.1%) [18].

MenACWY vaccination is often part of US college-entry requirements. Approximately 35.6% of US individuals aged 18–24 years were enrolled in US colleges in 2015 (the most recent update) [19]. Therefore, since college enrollment almost exclusively drives MenB vaccination, much of the adolescent and young adult population is being left unprotected against IMD during the period of highest risk.

These data collectively suggest that individuals who are not college-bound receive MenACWY and MenB vaccination less frequently than those attending college. An urgent need exists to rectify this disparity by providing comprehensive meningococcal immunization coverage to all adolescents and young adults. Because MenB is the predominant cause of IMD in the United States, every adolescent and his or her family, whether college-bound or not, should discuss MenB vaccination with their physician, consistent with the ACIP’s recommendation for shared clinical decision-making.

Declaration of funding

This work was supported by Pfizer Inc.

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Declaration of interest

All authors are employees of Pfizer Inc and may hold stock or stock options.

Author contributions

J Alderfer and A Srivastava were involved in study conception and design as well as analysis and interpretation of the data. M Moran and R Isturiz contributed to analysis and interpretation of the data. All authors were involved in drafting the manuscript or critically revising it for intellectual content.

Geolocation information

USA

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Acknowledgments

Statistical support was provided by Pingping Zhang, MS, of Pfizer. Editorial support was provided by Judith Kandel, PhD, of Complete Healthcare Communications, LLC (North Wales, PA), a CHC Group company, and was funded by Pfizer.