A study published in Open Forum Infectious Diseases found that the four-component meningococcal serogroup B vaccine (4CMenB; also known as MenB-4C) was associated with modest protection against gonorrhea among adolescents in a real-world setting with a high prevalence of disease.

“This is clinically important considering the role of asymptomatic infections in disease transmission and the risks of pelvic inflammatory disease and infertility in women, as well as antimicrobial resistance,” principal investigator and senior author Helen Marshall, MD, of the Women’s and Children’s Health Network, North Adelaide, Australia, said in an interview with this news organization.

The close genetic relationship between Neisseria gonorrhoeae and Neisseria meningitidis may explain emerging evidence that 4CMenB provides moderate protection against gonorrhea.

Dr. Marshall and colleagues assessed the impact of 4CMenB vaccination on gonorrhea and oropharyngeal meningococcal carriage among adolescents aged 14 to 19 years in Australia’s Northern Territory from 2021 to 2023 — a setting with a high prevalence of gonorrhea, particularly among Aboriginal and Torres Strait Islander populations. Vaccine effectiveness was assessed using linked notification and immunization data, while carriage was evaluated using oropharyngeal swabs collected at baseline and 12 months.

The vaccine effectiveness analysis included 30,650 adolescents, 9.6% of whom were fully vaccinated with two doses; 42.4% identified as Aboriginal or Torres Strait Islander. Gonococcal notifications were lower among vaccinated adolescents, the investigators reported, with a two-dose vaccine effectiveness of 38.4% (95% confidence interval [CI], 18.6%-53.4%).

“It is difficult to define a single clinically meaningful level of vaccine effectiveness,” Dr. Marshall stated. However, “in a setting with a high incidence of gonorrhea, a relative reduction of this magnitude [38.4%] could translate into preventing a substantial number of infections and complications.”

Overall meningococcal carriage rose from 4% to 6.2% (odds ratio, 1.68; 95% CI, 1.14-2.48), an increase driven by genogroup B and nongroupable strains, the investigators noted. Carriage of meningococci associated with disease was found to remain stable.

The investigators noted limitations, including lower-than-anticipated two-dose vaccine uptake, the potential for residual confounding related to differences in sexually transmitted infection risk and testing patterns and unavailable data on immunosuppression. Among the limitations of the carriage analysis, the target sample size was not reached, and 57% of 12-month swab data were missing and required imputation.

“Despite the limitations, the results demonstrate that the 4CMenB vaccine provides modest protection against gonorrhea in a real-world setting, in a population with a higher prevalence of gonorrhea and where rates are higher among women than men,” the investigators concluded. “These findings are important for women, considering infections are often asymptomatic and have the potential for serious complications.”

Since January 2025, 4CMenB has been available through a funded Territory Government program for infants aged 6 weeks to 12 months and year 9 students in the Northern Territory. However, Dr. Marshall stated that 4CMenB should be viewed as an additional measure for gonorrhea prevention rather than a replacement for established strategies.

“People who have received 4CMenB should not assume they are protected against all gonorrhea or alter their existing prevention and screening practices,” she emphasized.

Looking ahead, Dr. Marshall said the key unanswered question is why observational studies in adolescents, including the current study, have consistently suggested moderate protection against gonorrhea, whereas randomized trials in populations at very high risk have not demonstrated a significant benefit. “We need adequately powered randomized studies in adolescent populations (including women) vaccinated before repeated gonococcal exposure." she said. "These studies also need to establish how long any protection lasts and whether booster doses would be required.”

Dr. Marshall was an investigator on industry-sponsored vaccine trials. Her institution received investigator-led study funding from Pfizer and GSK; the authors reported no personal industry payments.