Observers had noted that gonorrhea incidence appeared to fall after the vaccination campaign, so Petousis-Harris' group made a decision to see if they could quantify the effect using a case control study of patients at sexually transmitted infection (STI) clinics in New Zealand. The vaccine used, known as "MeNZB", was created to protect against meningococcal group B infection - the cause of the most deadly form of meningitis.
A vaccine targeting the specific strain of bacteria causing meningococcal disease in the New Zealand outbreak was eventually "developed in a collaboration between Chiron Vaccines, the National Institute of Public Health of Norway (NIPH) and the New Zealand government", according to Mary Anne Rhyne, director of corporate communications at GlaxoSmithKline, the pharmaceutical company that inherited the vaccine from Chiron through a series of corporate acquisitions.
Scientists with pharmaceutical companies are working to develop a vaccine specifically against the infection.
Researchers previously noted a decline in gonorrhoea diagnoses in New Zealand after a mass vaccination programme for meningococcal B, a serious cause of life-threatening infections such as meningitis and blood poisoning.
"These cases may just be the tip of the iceberg since systems to diagnose and report untreatable infections are lacking in lower-income countries where gonorrhoea is actually more common", World Health Organization expert, Teodora Wi, said in Geneva.
Our research shows that protection against gonorrhoea could come from an unexpected source - a vaccine against meningococcal group B disease.
Interestingly, after analysing data obtained from sexual health clinics, researchers at the University of Auckland established that cases of gonorrhoea had fallen 31 per cent in those who had been vaccinated, thereby proving that the Men B jab provided "cross protection". If confirmed, the results represent the first instance of a vaccine reducing gonorrhea infections.
Gonorrhea is still treatable in the USA, said Bowen, though resistance to the current antibiotics may develop. The data show that individuals who were vaccinated were significantly less likely to have gonorrhea.
Further analysis was done to include the 1,002 people who had both infections.
The estimated vaccine effectiveness remained significant, they found, whether co-infected people were included as controls or cases - 29% and 23%, respectively.
MeNZB is a type of vaccine called an outer membrane vesicle vaccine.
But it's hard to form any firm conclusions because of the nature of the case and control groups.
"And then we tried a combination, and then it got resistant to those ones and now it's really hard to find a treatment that actually will treat it".
It could just be down to pure chance and have nothing to do with the vaccine.
The designers of the vaccine initially hand in mind to control meningitis epidemics but once OMV antigens known to prove an immune response to gonorrhea were added, the vaccine proved useful against the STD as well. "I wouldn't advise widespread use for the objective of gonorrhea prevention".
The findings should "reinvigorate" gonorrhea vaccine research, commented Kate Seib, PhD, of Griffiths University in Gold Coast, Australia. However, for many people, the infection is asymptomatic and so they can pass on the infection as they have no idea they have it. Meningococcal vaccines that protect against the other strains do not seem to have the same effect. One group had gonorrhea, and the other group had chlamydia, both of which are spread through sexual contact.