Meningococcal B Vaccine Fails to Prevent Gonorrhea in High-Risk Men: NEJM Trial
Australia: A randomized clinical trial has found that the four-component meningococcal serogroup B vaccine (4CMenB) did not reduce the incidence of Neisseria gonorrhoeae infection among men who have sex with men (MSM) at high risk for gonorrhea. The findings contrast with earlier observational studies that had suggested the vaccine might provide partial protection against the sexually transmitted infection.
The findings were published in the New England Journal of Medicine by Kate L. Seib and colleagues. The researchers evaluated whether the licensed meningococcal B vaccine could offer cross-protection against gonorrhea, for which no approved vaccine currently exists.
Gonorrhea remains one of the most common bacterial sexually transmitted infections worldwide, and rising antimicrobial resistance has made prevention an increasing public health priority. Because Neisseria gonorrhoeae and Neisseria meningitidis share several surface proteins, previous observational studies suggested that meningococcal B vaccines might also reduce the risk of gonorrhea. However, robust evidence from randomized clinical trials has been lacking.
To investigate this, researchers conducted a multicenter, double-blind, randomized, placebo-controlled trial involving men who have sex with men who were considered at high risk for gonorrhea. Eligible participants had recently been diagnosed with gonorrhea or infectious syphilis and were either receiving HIV pre-exposure prophylaxis (PrEP) while testing negative for HIV or were living with HIV. Participants were randomly assigned to receive two doses of the 4CMenB vaccine or placebo and underwent quarterly screening for sexually transmitted infections over a two-year follow-up period.
Key findings from the study include:
- The trial enrolled 654 participants, with 587 included in the primary efficacy analysis.
- Gonorrhea incidence was 48.1 cases per 100 person-years in the vaccine group and 47.8 cases per 100 person-years in the placebo group.
- The vaccine showed no significant protective effect against gonorrhea, with an estimated vaccine efficacy of −0.5%.
- No meaningful benefit was observed for symptomatic or asymptomatic gonorrhea infections.
- The vaccine also failed to reduce infections at urogenital, anorectal, or oropharyngeal sites.
- Serious adverse events occurred in 4.7% of vaccinated participants compared with 2.8% of those receiving placebo.
The researchers noted that despite encouraging findings from previous observational studies, this rigorously designed randomized trial did not demonstrate any reduction in gonorrhea risk with the meningococcal B vaccine. The results suggest that the associations reported in earlier studies may not reflect a true protective effect.
The investigators concluded that the four-component meningococcal serogroup B vaccine should not be considered an effective strategy for preventing gonorrhea in men at high risk for infection. They emphasized the continued need to develop vaccines specifically targeting Neisseria gonorrhoeae, particularly in light of the growing threat of antimicrobial resistance and the global burden of gonorrhea.
Reference:
DOI: 10.1056/NEJMoa2516739
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