According to researchers, encouraging trial results have brought a chlamydia vaccine one step closer.
Nowadays, the most prevalent sexually transmitted infection (STI) in the US and the UK is chlamydia. The UK had nearly 200,000 cases in 2022, up 24.3% from the previous year, according to the most recent data.
A major cause of infertility in women, the condition frequently shows no signs. In the event that treatment is not received, it may result in pelvic inflammatory disease and reproductive organ scarring.
The development of a commercial vaccination, however, requires the production of an immune response, which is now demonstrated by researchers in the UK and Denmark from an experimental vaccine.
The study, published in The Lancet Infectious Diseases, involved more than 150 people – half women, half men, with an average age of 26.
None of the participants had chlamydia.
Chlamydia: the symptoms
Most people who have chlamydia don’t notice any symptoms. When symptoms do appear, it is usually between one and three weeks after having unprotected sex with an infected person.
Even when symptoms do appear, they may only last a few days, but the infection can remain and be passed on if not treated.
Chlamydia symptoms in women
- pain when urinating
- unusual vaginal discharge
- pain in the tummy or pelvis
- pain during sex
- bleeding after sex
- bleeding between periods
Chlamydia symptoms in men
- pain when urinating
- white, cloudy or watery discharge from the tip of the penis
- burning or itching in the urethra (the tube that carries urine out of the body)
- pain in the testicles
Chlamydia can also infect the rectum, throat and eyes.
The team, working at the National Institute for Health Research in London, tested different dosages of the vaccine in participants, who received either the test jab or a placebo three times over four months.
However, while the vaccine produced an immune response – potentially helping the body fight off the infection itself, there is still a way to go.
Dr Hilary Reno, medical director of the St Louis County Sexual Health Clinic, said questions remained.
‘Does it confer the ability to hold off infection with chlamydia?’ she said. If you do have an infection, does it mean you’re more likely to have an asymptomatic infection?
‘We don’t know that and that’s what the next phase of studies would be.’
Chlamydia is caused by a bacteria, Chlamydia trachomatis, which can also infect the eyes, causing vision loss in 1.9 million people worldwide according to the US Centers for Disease Control and Prevention (CDC).
The team also tested the vaccine in eye drop form, and were pleased by the results.
Co-author Dr Jes Dietrich, from the Statens Serum Institut in Denmark, said: ‘I was very pleasantly surprised because it’s really difficult to induce immunity in the eye.’
David Harvey, executive director of the National Coalition of STD Directors, told NBC News: ‘This is desperately needed.
‘We have the highest STI rates in America since the 1950s and possibly beyond.’
Vaccines are available for other STIs. In 2008 the UK began offering a vaccine against human papilloma virus (HPV), a disease which can lead to cervical cancer, while a hepatitis B vaccine is also available.
More recently, officials have been encouraging those at risk to take the mpox vaccine following a surge in cases.
