What is meningococcus?
The scientific name of meningococcus is Neisseria meningiditis. While meningococcal disease was first described in 1805 during an epidemic in Geneva, Switzerland, it wasn’t until 1882 that the bacteria was isolated and identified for the first time. Eight years later scientists discovered that the germ can be carried in the nose and throats of healthy individuals. Carriage of this bacteria in healthy, symptom-free individuals varies by age group: 4-5% of infants and children, 7-8% middle-aged adults, 10-25% of late teens/early adults.
As noted in last month’s blog, prior to its vaccine development, Hib, was the leading cause of bacterial meningitis in infants and toddlers. Meningococcus is now the leading cause of bacterial meningitis in both children and adolescents in the U.S. Viruses can also cause meningitis, but discussion of such is beyond the scope of this blog.
Meningitis is inflammation of the meninges – the lining that protects the brain and spinal cord. The onset of meningococcal meningitis symptoms is so quick that a patient can go from completely healthy to a life-threatening state in just a few hours. Meningococcal meningitis kills approximately 1 in 8 infected patients. If meningococcus infects the bloodstream the fatality rate is closer to 40%. Meningococcus can also cause infection of the lungs, heart muscle, heart lining, joints, eyes and urethra. Of those who survive infection, 20% will suffer significant complications such as hearing loss, digit or limb amputations, skin scarring and/or grafting, kidney disease, seizures, intellectual disability, impaired school performance, behavioral problems, and attention deficit disorder.
There are many strains of meningococcus, but the ones most responsible for human infection in the United States are A, B, C, W and Y. Consequently, these are the strains for which we have vaccines. Sometimes these vaccines are referred to by the shorthand MenACWY and MenB.
How is meningococcus spread?
Meningococcus is only spread from human to human. Spread requires close contact with nose, mouth or throat secretions of an infected individual (e.g. nasal discharge, saliva, or airborne droplets from coughing or sneezing). Close contact could be kissing, sharing food/drinks, or being in the same room or house for 4 or more hours per day (e.g. home, daycare, school classroom, dorm room or other cohabiting residence).
The incubation period (i.e. time between exposure and development of symptoms) is 1 to 10 days, but typically 4 days or less.
Can meningococcal infections be treated?
Yes, we do have antibiotics that can treat meningococcal infections. They need to be administered through an IV. Because meningococcal infections progress so rapidly, patients are often extremely sick by the time treatment can be initiated. As noted above, even those fortunate enough to be successfully treated with antibiotics have a 20% chance of significant long-term complications. Therefore, prevention of these extremely serious infections is the key!
How long have meningococcal vaccines been around?
The first meningococcal vaccines made in the 1960s-1980s did not create as effective or as long-lasting of an immune response as those we use today, especially in children. The current conjugate meningococcal vaccines have been around since the late 1990s. In 2005 the MenACWY vaccine became a recommended routine immunization for 11-12 year olds. Since that time, annual incidence of meningococcal infection in the United States has decreased by 75%. In 2010 a booster dose at age 16 was approved and recommended to address follow-up data suggesting decreasing immunity 5 years after administration of the 1st dose.
What type of vaccine is it?
MenACWY vaccines are polysaccharide conjugate vaccines. Meningococcus, like Hib, has sugars (i.e. polysaccharides) on its surface that both help it infect human cells and serve as an attack point for our immune systems. Conjugate vaccines are made by attaching the bacteria’s surface sugars to a harmless carrier protein that helps our bodies make and maintain a protective immune system response. It was the creation of the conjugate Hib vaccine in the late 1980s that paved the way for the more effective and longer-lasting meningococcal vaccines we have today.
The B strain meningococcal (MenB) vaccine has been more challenging to develop because its surface sugar closely resembles sugars that naturally occur on human cells. The result of a polysaccharide conjugate MenB vaccine could therefore cause autoimmunity (i.e. antibodies inadvertently attack the cells of the person they’re supposed to be protecting). Instead, surface proteins, rather than sugars, are used as the antigen (i.e. part of the organism that our immune systems recognize).
The differences between MenB and the other 4 strains is also why it’s taken longer to develop a combined MenABCWY vaccine, the first of which was FDA approved in 2024.
When do pediatric patients receive the meningococcal vaccine?
As of the writing of this blog, MenACWY vaccines are recommended in the U.S. at age 11 with a booster dose at 16 years old. MenB vaccination is recommended between the ages of 16 and 18 years old. Teens and young adults have the greatest risk for meningococcal infection in the United States because of high symptom-free carriage rates, common co-dwelling practices at camps, colleges and military training sites, and social behaviors that increase exposure to this nose/mouth/throat-dwelling bacteria. As population carriage and infection rates change, and updated versions of these vaccines are created, recommendations may change.
Children less than 11 years old with no spleen or a non-functioning spleen, with complement deficiency (a type of immunodeficiency), who are traveling to sub-Saharan Africa between December and June, or who have been exposed in an outbreak are also recommended to receive meningococcal vaccines.
What are possible side effects of the meningococcal vaccine?
The most common side effects are arm soreness or localized reactions such as injection site redness or swelling. Patients may also experience headache, muscle aches, fatigue or malaise.
Why should I vaccinate my child against meningococcus?
The stakes are high. Though it is thankfully a rare infection (in large-part due to vaccination efforts), meningococcal infections’ rapid rate of symptom onset and progression, high fatality rates, and high long-term complication rates for survivors make this a germ worth protecting against through prevention. Some studies have also shown vaccination can decrease carriage rates of the bacteria in healthy, symptom-free individuals.
References
2024. “Meningococcal Infections”, Red Book: 2024–2027 Report of the Committee on Infectious Diseases, Committee on Infectious Diseases, American Academy of Pediatrics, David W. Kimberlin, MD, FAAP, Ritu Banerjee, MD, PhD, FAAP, Elizabeth D. Barnett, MD, FAAP, Ruth Lynfield, MD, FAAP, Mark H. Sawyer, MD, FAAP
https://www.chop.edu/vaccine-education-center/vaccine-details/meningococcal-vaccine
Lee H. Harrison, Kathleen A. Shutt, Kathryn E. Arnold, Eric J. Stern, Tracy Pondo, Julia A. Kiehlbauch, Robert A. Myers, Rosemary A. Hollick, Susanna Schmink, Marianne Vello, David S. Stephens, Nancy E. Messonnier, Leonard W. Mayer, Thomas A. Clark, Meningococcal Carriage Among Georgia and Maryland High School Students, The Journal of Infectious Diseases, Volume 211, Issue 11, 1 June 2015, Pages 1761–1768, https://doi.org/10.1093/infdis/jiu679
Balmer P, Burman C, Serra L, York LJ. Impact of meningococcal vaccination on carriage and disease transmission: A review of the literature. Hum Vaccin Immunother. 2018 May 4;14(5):1118-1130. doi: 10.1080/21645515.2018.1454570. Epub 2018 May 9. PMID: 29565712; PMCID: PMC5989891.
Borrow, R., & Findlow, J. (2024). The important lessons lurking in the history of meningococcal epidemiology. Expert Review of Vaccines, 23(1), 445–462. https://doi.org/10.1080/14760584.2024.2329618
Goldblatt D. Conjugate vaccines. Clin Exp Immunol. 2000 Jan;119(1):1-3. doi: 10.1046/j.1365-2249.2000.01109.x. PMID: 10671089; PMCID: PMC1905528.
Shea MW. The Long Road to an Effective Vaccine for Meningococcus Group B (MenB). Ann Med Surg (Lond). 2013 Nov 4;2(2):53-6. doi: 10.1016/S2049-0801(13)70037-2. PMID: 25628885; PMCID: PMC4306095.
https://www.fda.gov/media/137306/download
https://www.cdc.gov/vaccines/hcp/current-vis/downloads/mening.pdf
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
Balmer P, Burman C, Serra L, York LJ. Impact of meningococcal vaccination on carriage and disease transmission: A review of the literature. Hum Vaccin Immunother. 2018 May 4;14(5):1118-1130. doi: 10.1080/21645515.2018.1454570. Epub 2018 May 9. PMID: 29565712; PMCID: PMC5989891.