meningococcal vaccine

Researchers at the University of Auckland in New Zealand have discovered that a meningococcal vaccine is effective against gonorrhoea.

 

Gonorrhoea is a sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae. The infection typically originates in warm, moist areas of the body, such as the urethra, eyes, throat, vagina, anus, and female reproductive tract. While many individuals experience no symptoms, men may demonstrate burning with urination, discharge from the penis, or testicular pain, while women may have burning with urination, vaginal discharge, vaginal bleeding between periods, or pelvic pain. Women and men may suffer from complications of the infection, such as pelvic inflammatory disease and inflammation of the epididymis, respectively. Gonorrhoea can lead to infertility and chronic pain, and will ultimately spread and cause damage to the joints or heart valves if left untreated. The infection is transmitted through sexual contact (oral, anal, and vaginal sex) with an infected person, as well from mother to child during birth.

With an estimated 78 million new cases recorded annually, gonorrhoea has developed into a serious global public health concern. Drug resistance further complicates an already serious health crisis, since the emergence of extensively drug-resistant strains of gonorrhea in the 1940’s. Unfortunately, up until now, the development of an effective vaccine has been futile and unproductive. However, observational data indicates that outer membrane vesicle (a nano-scale sac used for bacterial communication) meningococcal group B vaccines (MeNZB) impact the incidence of gonorrhoea.

A study published in The Lancet evaluated the effects of the outer membrane vesicle meningococcal vaccine against gonorrhoea in young adults between the ages of 15 and 30 years in New Zealand.  A retrospective case-control study was conducted on data retrieved from 11 sexual health clinics in New Zealand, analyzing a study population of 14,730 patients born between January 1st, 1984, and December 31st, 1998, who were eligible to receive MeNZB vaccinations, and diagnosed with gonorrhoea or chlamydia, or both.  Controls consisted of patients with a positive chlamydia test only.

Using statistical analyses, the study compared disease outcomes in vaccinated and unvaccinated participants, calculating vaccine effectiveness.  According to the data, the probability of a vaccinated individual being a control rather than a case was significantly more likely.  The study revealed that the estimatedmeningococcal vaccine effectiveness against gonorrhoea was 31%, meaning that inoculation with the vaccine appears to be associated with significantly lower likelihood of contracting gonorrhea compared with not being vaccinated.  The study reported a clear association between exposure to MeNSB and reduced rates of gonorrhoea diagnosis – a paramount finding in gonorrhoea research, as a vaccine has not before proved to possess protective properties against gonorrhoea.

This ground-breaking research provides experimental evidence for cross-protection against related organisms by immunological mechanisms, demonstrates for the first time that outer membrane vesicle vaccines can affect a mucosal infection, and has the potential to illuminate prospective vaccine development for both gonorrhoea and meningococcal vaccines. The significant influences the meningococcal vaccines have on gonorrhoea incidence suggest that future research should be focused on identifying the antigens responsible for this effect.

Written by Jordyn Posluns, B.Sc. (Hons)

Reference: Petousis-Harris H, Paynter J, Morgan J, et al. Effectiveness of a group B outer membrane vesicle meningococcal vaccine against gonorrhoea in New Zealand: a retrospective case-control study. The Lancet. 2017 July 10.

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