Exposure to the meningococcal group B vaccine is associated with a reduced likelihood of contracting gonorrhoea, according to the findings of a large study published in The Lancet
The study, carried out during a mass vaccination campaign in New Zealand, involved more than 14,000 people.
Dr Helen Petousis-Harris, University of Auckland, New Zealand, and lead author of the study, said: “This is the first time a vaccine has shown any protection against gonorrhoea. Our findings could inform future vaccine development for both the meningococcal and gonorrhoea vaccines.”
If the effect is confirmed in other available and similar meningococcal group B vaccines, researchers who carried out the study say that administering the vaccine in adolescence could result in significant declines in gonorrhoea, which has increasingly become drug resistant. The vaccine may even help to reduce rates of infection.
Despite the two diseases — Neisseria gonorrhoeae and Neisseria meningitides— being very different in terms of symptoms and how it is transmitted, there is an 80–90% genetic match, which could provide a means of cross-protection.
In New Zealand, approximately one million people (81% of the population under 20 years) received the MeNZB vaccine — an outer membrane vesicle (OMV) meningococcal group B vaccine — during a mass immunisation programme in 2004–2006. This provided researchers with an opportunity to test the idea of cross-protection.
They used data for all people aged 15-30 who had been diagnosed with gonorrhoea or chlamydia, or both, at 11 sexual health clinics, who were eligible to receive the MeNZB vaccine during the 2004–2006 vaccination programme.
A total of 14,730 cases and controls were included in the analysis (1,241 cases of gonorrhoea; 12,487 cases of chlamydia; 1,002 cases of co-infection). Vaccinated individuals were less likely to have gonorrhoea than controls (41% vs 51%). Researchers concluded that for those people who had previously received the MeNZB vaccine there was a reduced incidence of gonorrhoea by approximately 31%.
MeNZB was developed to control a meningitis epidemic and is no longer available, but the OMV antigens thought to provoke the immune response to gonorrhoea have been included in the more recently developed 4CMenB vaccine, available in many countries. The authors say more research is now needed.
The study follows a warning from the World Health Organization (WHO) that untreatable strains of gonorrhoea are on the rise. Gonorrhoea is the second most common bacterial sexually transmitted infection (STI) in the UK after chlamydia, with almost 35,000 cases reported in England in 2014.
The WHO estimates that 78 million people worldwide contract the disease each year, with most cases affecting people under the age of 25.
 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. doi: 10.1016/S0140-6736(17)31449-6