A discontinued vaccine against a bacteria that causes brain inflammation also shielded people against gonorrhea, researchers said Tuesday.
Using a condom or abstaining from sex are currently the only ways to avoid contracting gonorrhea, which infects about 80 million people every year, according to the World Health Organization.
As drug resistance spreads, doctors are diagnosing more and more cases that cannot be treated by antibiotics, making it a major public health concern. , the WHO said there was an urgent need for new drugs to prevent and treat gonorrhea, often called "the clap", which is spread by vaginal, oral and anal sex.
For the new study, researchers looked at diagnosed gonorrhea cases among people who would have been eligible for a meningococcal B vaccine administered to over a million New Zealanders between 2004 and 2006.
Meningococcal bacteria, spread through coughing or kissing, can cause meningitis, an inflammation of the brain and spinal cord, and a blood infection called septicaemia. Both can be fatal.
While they are vastly different in symptoms and transmission, the meningitis and gonorrhea bacteria are a very close genetic match, the researchers said.
Experts recently noticed a decline in gonorrhea after meningococcal B vaccine campaigns. So the team set out to investigate, and found that people who got the meningitis vaccine in New Zealand "were significantly less likely to have gonorrhoea" than people who did not get the shot.
The vaccine was estimated to have reduced gonorrhoea cases by 31 percent -- a level that would decrease the prevalence of the disease by about a third within 15 years.
"This is the first time a vaccine has shown any protection against gonorrhoea," said study co-author Helen Petousis-Harris of the University of Auckland in New Zealand.
How the immune system is triggered for gonorrhea is not understood, and the vaccine, used in a specific outbreak, is no longer available. Some of the same molecules were used, however, to manufacture another meningococcal vaccine that is still in use.
Further study is crucial to determine how the meningitis shot blocked gonorrhoea, Kate Seib of the Institute for Glycomics at Australia's Griffith University wrote in a comment on the study.
"In light of the high burden of disease and the threat of gonorrhoea becoming untreatable because of antibiotic resistance, there is an increased imperative to revisit vaccine options and reinvigorate research in this field."
