A meningitis vaccine may also help to protect against gonorrhoea, researchers say today.
It is the first time such a therapy has provided hope for people with the drug-resistant sexually transmitted infection (STI).
A study, published in The Lancet Infectious Diseases journal found that exposure to the meningococcal group B vaccine during a mass vaccination campaign was associated with a 31% reduced likelihood of contracting gonorrhoea, compared with people who had not been vaccinated.
The researchers say if a similar result is shown in other similar meningococcal group B vaccines, giving the vaccine to teenagers could lead to significant declines in the STI.
Over the past 100 years, attempts to develop a vaccine against gonorrhoea have been unsuccessful and while four vaccine candidates have reached clinical trial stage, none has been effective.
However, analysis of population data suggests a decline of gonorrhoea cases in Cuba, New Zealand and Norway after people were injected with the outer membrane vesicle (OMV) meningococcal group B vaccination as part of mass vaccination campaigns.
Although there are marked differences between gonorrhoea and meningitis, there is an 80-90% genetic match between the Neisseria gonorrhoeae and Neisseria meningitidis bacteria.
For this study, Researchers at the University of Auckland, New Zealand, used data from a mass vaccination programme that took place between 2004 and 2006 in the country, which saw about one million people under the age of 20 – about 81% of that population – receive the MeNZB vaccine, an OMV meningococcal group B vaccine.
They looked at all people aged 15-30 who had been diagnosed with gonorrhoea and/or chlamydia at 11 sexual health clinics and who were eligible to receive the MeNZB vaccine during the vaccination programme.
They used 14,730 cases and controls in the analysis, which comprises 1,241 cases of gonorrhoea; 12,487 cases of chlamydia; and 1,002 cases of co-infection.
Researchers discovered that those who were vaccinated were significantly less likely to have gonorrhoea compared with the control group (41% vs 51%). They said having the MeNZB vaccine reduced the incidence of gonorrhoea by approximately 31%.
Dr Helen Petousis-Harris, University of Auckland and lead author of the study, said: "Our findings provide experimental evidence and a proof of principle that an OMV meningococcal group B vaccine could offer moderate cross-protection against gonorrhoea. This is the first time a vaccine has shown any protection against gonorrhoea.
“At the moment, the mechanism behind this immune response is unknown, but our findings could inform future vaccine development for both the meningococcal and gonorrhoea vaccines."
Previous models have suggested that a vaccine with 30% efficacy could decrease prevalence of gonorrhoea by more than 30% within 15 years, if immunity is maintained. Higher efficacy would offer greater protection over a shorter period of time.
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 10 July 2017; doi: 10.1016/ S0140-6736(17)31449-6 [abstract]
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