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How effective is Meningococcal vaccine?

Updated April 07, 2023

vaccine effectiveness

Menactra (MCV4 or MenACWY-D), the first meningococcal (serogroups A,C, Y, and W-135) conjugate vaccine received FDA approval in January of 2005 on the basis that the vaccine was not inferior in safety or immunogenicity when compared with Menomune meningococcal polysaccharide vaccine, the only FDA approved meningococcal vaccine available at the time. Clinical trials on Menactra’s efficacy were not a requirement for FDA licensing and the vaccine’s immunogenicity was based on blood antibody testing completed 28 days following vaccine administration. In the spring of 2005, when the CDC’s Advisory Committee on Immunization Practices (ACIP) voted that all 11-12-year olds be administered the vaccine, it acknowledged that immunogenicity data was not sufficient enough to determine the vaccine’s effectiveness. Further, data was not available to determine whether the vaccine could reduce or eliminate vaccine type meningococcal bacteria from the nasopharyngeal region and prevent persons who carried the bacteria from spreading it to others. As well, while the committee recommended that Menactra be administered at the same time as the newly licensed Tdap vaccine, no clinical trials had examined whether administering both vaccines simultaneously would be effective or even safe. 

Menveo (MenACWY-CRM), the second meningococcal (serogroups A, C, Y, and W-135) conjugate vaccine received FDA approval in February of 2010 based on safety and immunogenicity studies reporting the vaccine to be non-inferior to Menactra (MCV4/ MenACWY-D) vaccine. As with Menactra vaccine, no vaccine efficacy studies had ever been completed nor had any studies determined whether or not the vaccine could reduce or eliminate nasopharyngeal carriage. However, ACIP approved the vaccine for use when meningococcal vaccination was indicated. 

When ACIP initially recommended routine vaccination of all 11-12 year olds with Menactra meningococcal conjugate vaccine in 2005, committee members estimated that a single dose of the vaccine would be effective for an average of 22 years.  However, by October of 2010, five years after the initial approval vote, ACIP voted to add a booster dose of meningococcal vaccine at age 16. By this time, data on vaccine effectiveness had determined that by age 16 to 21 years, at a time when the risk of meningococcal disease was noted to be higher, more than 50 percent of 11-12-year olds would lack any protection from the vaccine and be at risk for developing meningococcal disease.  

A 2017 published study on Menactra (MenACWY-D) vaccine effectiveness found that overall, a single vaccine dose was between 51 and 80 percent effective. Within one year after vaccination, the vaccine was found to be between 49 and 91 percent effective, and after 1 to 3 years, this number decreased to between 44 and 83 percent. MenACWY-D vaccine was found to be only 25 to 79 percent effective by 3 to 8 years following vaccination. Study authors concluded that a booster dose of meningococcal conjugate vaccine would likely provide more long-term vaccine acquired immunity, but also stated that “the additional impact gained from the booster dose in terms of cases prevented is likely to be limited.” 

MenQuadfi (Sanofi Pasteur), a third meningococcal conjugate vaccine, received FDA approval for use in April 2020 based on clinical trials that reported the vaccine was not inferior in safety or immunogenicity when compared with Menomune, Menactra, and Menveo.   

As with meningococcal conjugate vaccines, meningococcal serogroup B (MenB) vaccines received FDA approval based on blood tests indicating immune response (immunogenicity) to the particular strains found within the vaccine. Meningococcal serogroup B strains, however, are quite diverse, and as a result, vaccine effectiveness is difficult to assess. Moreover, with meningococcal serogroup B disease rates at historical lows and disease outbreaks sporadic even prior to the licensing of TRUMENBA (MenB-FHbp) and BEXSERO (MenB-4C) vaccines, data on the effectiveness of meningococcal group B vaccines was considered almost impossible to attain. Immunogenicity, however, is not necessarily indicative that either available Men B vaccine is, in fact, effective against any of the various meningococcal group B strains that may be circulating in the environment.  

While ACIP recommends that all persons with complement component deficiencies as well as those taking the medication eculizumab (Soliris®) be vaccinated with a meningococcal conjugate vaccine as well as a Men B vaccine, all meningococcal vaccine package inserts state that these individuals will continue to remain at high risk of meningococcal disease even if they develop antibodies following vaccination.        Several published studies have reported on the failure of meningococcal vaccines to offer protection in this particular susceptible population.         

According to unpublished data submitted by Pfizer to ACIP in 2015, blood antibody levels believed to be indicative of a protective immune response decrease quickly after three doses of TRUMENBA (MenB-FHbp) vaccine. This data reported that within four years, only about 50 percent of vaccine recipients had blood antibody levels above or at the lowest acceptable level indicative of an immune response but only to three out of four of the meningococcal serogroup B vaccine strains tested.  

In BEXSERO (MenB-4C) pre-licensing immunogenicity trials, the three antigen strains found within the vaccine were measured in college students in the United Kingdom at 1 and 11 months following the administration of two doses of the vaccine. At one month, 88 percent of vaccine recipients had an immune response considered to be protective, however by 11 months, this number decreased to only 66 percent. The long-term effectiveness of BEXSERO vaccine is unknown at this time. 

In late 2013 - early 2014, and prior to FDA approval, the FDA and CDC approved BEXSERO (MenB-4C) for use during an outbreak of meningococcal serogroup B invasive disease at Princeton University. In 2016, a published study reported that nearly 34 percent of vaccine recipients had no evidence of a protective immune response against the particular meningococcal serogroup B strain responsible for the outbreak at Princeton University eight weeks following the second dose.  While no additional cases of meningococcal serogroup B invasive disease occurred among vaccine recipients at Princeton University, one additional fatal case was reported during the same time period in a student attending another university who had a history of close contact with several Princeton University students. This additional case provided evidence that the vaccine did not eliminate N. meningitidis serogroup B carriage and that vaccinated individuals who carry serogroup B meningococci in their nasopharyngeal area could still transmit the bacteria and potentially cause invasive disease in others. 

A 2017 published study examining meningococcal carriage during an outbreak of meningococcal serogroup B at a large university in Oregon found that neither BEXSERO (MenB-4C) nor TRUMENBA (MenB-FHbp) had any impact on meningococcal nasopharyngeal carriage reduction and that implementing vaccine programs to target meningococcal serogroup B did not result in herd protection. High vaccination rates coupled with the use of preventative antibiotics in persons with a history of close contact to a person diagnosed with invasive meningococcal disease was recommended during an outbreak, with study authors encouraging that further research be completed to determine “the effectiveness, coverage, and duration of protection afforded by both MenB vaccines.” 

NVIC “Quick Facts” is not a substitute for becoming fully informed about Meningococcal disease, meningitis and the Meningococcal vaccine. NVIC recommends consumers read the more complete information following the "Quick Facts", as well as the vaccine manufacturer product information inserts, and speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child.



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