A vaccine to protect against chlamydia has moved closer to becoming reality after a pioneering clinical trial found the treatment to be safe.
The vaccine successfully provoked an immune response, boosting levels of antibodies against the chlamydia bacterium in the blood and vaginal fluids.
About 131m cases of the sexually transmitted infection are diagnosed worldwide every year.
Chlamydia can be treated with antibiotics, but infection often has no symptoms and many people are unaware they have it.
Without treatment, it can lead to a range of complications for men and women, including fertility issues and an increased risk of HIV.
Dr Frank Follmann, the head of chlamydia vaccine research at Statens Serum Institut in Denmark and a co-author of the study, said: “Chlamydia is a hidden epidemic.
It is very well adapted to infecting both men and women and in most cases it does it without any symptoms.”
There have been recent drives to improve testing through screening programs, particularly among young people. The study’s authors say such measures have failed to tackle the problem and suggest a vaccine would be beneficial.
Clinical Tests on Chlamydia Vaccine
Writing in the Lancet Infectious Diseases journal, the researchers describe how they tested two formulations of a vaccine. Each type given to 15 women aged between 19 and 45 who did not have chlamydia. Another five chlamydia-free women were given a placebo.
All received three injections into their arm muscle over four months, followed by two doses administered through a nasal spray in the weeks after. Neither the women nor those monitoring the impact of the vaccine were aware of who was in which group.
The results showed no serious adverse reactions to the vaccines. The vaccinations, but not the placebo, produced an immune response.
Follmann said the presence of antibodies in vaginal fluid was important. “We see the antibodies as a first line of defence,” he said. “They should be able to target the bacteria once it enters the genital tract.”
He said the study suggested the injection could provide sufficient protection against chlamydia, without the need for the nasal spray.
The findings raise hopes that the vaccine could eventually be given at the same time as the HPV vaccine, which protects against certain cancers including that of the cervix.
The treatment is still at an early stage of development, but the team said the trial results were promising and that testing should proceed to the next stage with a larger number of participants.
“The next step is to test whether or not it could in fact protect [against chlamydia infection] in humans,” Follmann said.