A vaccine used to prevent meningitis in young people also cuts the rate of the sexually transmitted infection (STI) gonorrhoea, which is caused by a related bacterium.
The vaccine’s effect is relatively modest, lowering rates of the STI by up to 40 per cent, but it could still have a useful impact on rates of the infection, especially as antibiotic-resistant cases are on the rise, says Helen Marshall at Women’s and Children’s Hospital in Adelaide, Australia.
Gonorrhoea, also known as the clap, can cause pain and discharge from the genitals in men or women, but in up to half of women and a tenth of men it causes no symptoms. Left untreated, it can cause infertility in women and blindness in babies born to infected mothers.
The STI is proving increasingly hard to treat, because the bacteria are becoming more resistant to standard antibiotics. Even after successful treatment, people may get repeated reinfections. Some “super-gonorrhoea” strains are resistant to nearly all possible antibiotics.
The meningitis vaccine, called 4CMenB, was designed to target a bacterium called Neisseria meningitidis, which is a cause of brain infections, and is closely related to the gonorrhoea-causing Neisseria gonorrhoeae. Some of the antibodies generated by the meningitis vaccine bind to the gonorrhoea bacteria.
The 4CMenB vaccine was introduced in Australia for people aged between 17 and 20 in 2019. Marshall’s team compared the rates of gonorrhoea in people who did or didn’t get the meningitis vaccine. This showed that receiving the two required doses of the vaccine reduced the chances of getting gonorrhoea by 33 per cent.
A similar study in the US, where the vaccine was introduced for 16 to 23-year-olds in New York and Philadelphia, found the effectiveness of the vaccine to be 40 per cent.
“Even though the effectiveness is moderate rather than high, it still would see a really impactful reduction in gonorrhoea,” says Marshall.
In a modelling study, Peter White at Imperial College London and his colleagues found that it would be cost-effective to offer the meningitis vaccine to men who have sex with men if they are attending STI clinics, because they are at high risk for the infection. This would include those who test positive for gonorrhoea or say they have more than five sexual partners a year.
Ideally, we would offer people a vaccine against gonorrhoea that is more effective, says Colin Garner, head of the Antibiotic Resistance UK charity. “But anything that can be used against these types of resistant bacteria is obviously of interest. Antibiotic-resistant gonorrhoea is becoming an increasing problem.”