First Effective Vaccine Against Gonorrhea Reduces Infection Rate by 31% — by Accident

Sex makes the world go 'round, and when it does, so does gonorrhea. Finally some good news on the growing menace of drug-resistant gonorrhea — a large, long-term study shows a vaccine may work in reducing the incidence of an increasingly dangerous infection.

The announcement of this first step against the too-common sexually transmitted disease (STD) gonorrhea, comes at the same time the World Health Organization (WHO) has issued an alert that the infection is becoming, in some cases, impossible to treat. And this resistant disease is popping up everywhere.

According to WHO, factors contributing to the 78 million new cases of gonorrhea diagnosed annually around the world include spread from globalization, decreased use of condoms, and inadequate surveillance, detection, and ineffective or inappropriate treatment. Add a wily, mercurial bacterium, and you have a global public healthcare menace. Notes WHO Medical Officer, Teodora Wi, in a press release, "The bacteria that cause gonorrhea are particularly smart. Every time we use a new class of antibiotics to treat the infection, the bacteria evolve to resist them."

For researchers at the University of Auckland in New Zealand, a look back at a meningitis vaccine that seemed to decrease gonorrhea infection rates lead to a breakthrough in how we might use a vaccine as our front line offense against gonorrhea. Their study, published in The Lancet, tells the story.

Reducing Infection with Gonorrhea by Protecting Against Meningitis

According to commentary from the Lancet Editorial Board, an estimated one in 12 people has a herpes simplex virus (HSV) infection, and the numbers of cases of chlamydia, bacterial vaginosis, syphilis, and gonorrhea continue to rise. The commentary calls for improved public policy to increase surveillance, diagnostics, and treatment of STDs around the world — a topic that does not have the focus or funding like the prevention and treatment of HIV.

The potential for a vaccine to reduce gonorrhea infection rates occurred as a side story to a large-scale immunization program undertaken by the New Zealand Ministry of Health. Between 2004 and 2006, the Ministry vaccinated more than 1.1 million young people to stop the spread of an epidemic strain of meningitis, caused by the bacteria Neisseria meningitides.

This fluorescent antibody-stained micrograph depicts a positive result testing for the presence of gonorrhea.

In the Lancet study, researchers investigated an association between the wide-spread use of the meningitis vaccination and declining rates of gonorrhea in New Zealand. The research team, using database records, conducted a retrospective, controlled, study of patients between ages 15 and 30 who were eligible to receive the meningitis vaccination when they were younger. A "retrospective" clinical study looks back on incidence or rates of disease, usually through electronic health records, studies, or other documents.

Because gonorrhea and meningitis cause completely different infections, it may seem weird to connect — or control — the two infections with the same vaccine. As it turns out, Neisseria gonorrhoeae and Neisseria meningitides have a genetic match of about 80% to 90%, which creates a reasonable chance that the remedy for one, could help stop the other.

Working through a database, population data, and information from sexual health clinics, and adjusting for control factors, the study weighs in like this:

• Vaccinated patients had far fewer cases of gonorrhea. The estimated effectiveness of the meningitis vaccination against gonorrhea was 31 percent.
• During the study review period, there were 1,241 cases of gonorrhea, and 12,487 cases of chlamydia — an STD that commonly occurs as a co-infection with gonorrhea.
• Study authors note the findings are "proof of principle" toward future development of vaccines against both gonorrhea and meningitis.
• The effectiveness of the vaccine could be different depending on bacterial strains involved in the gonorrhea infection.

Particularly important is that this first successful finding involving a vaccine that reduces the spread of gonorrhea by even 31%, follows more than a century of unsuccessful research and attempts to find a way to protect humans from gonorrhea. Initial infection with the bacteria provides no forward immunity to its victims and four vaccines, so far, have proved unsuccessful in preventing the disease.

The long-term effects of gonorrhea on its victims, particularly women, is well-known, and like other STDs, many people do not know they have it — spreading the infection more deeply into any population.

Lead author, Helen Petousis-Harris, with the University of Auckland, remarks in a press release: "This is the first time a vaccine has shown any protection against gonorrhea. At the moment, the mechanism behind this immune response is unknown, but our findings could inform future vaccine development for both the meningococcal and gonorrhea vaccines."

Data modeling suggests that a reduction in the infection rate by 30% could decrease the rate of gonorrhea by 30% within the next 15 years. With a new door opened to the potential development of a fully effective gonorrhea vaccine, the news about multi-drug resistant Gonorrhea just got a little less grim.

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Cover image by See-ming Lee/Flickr