Chlamydia vaccine shows promise in phase I studies

Chlamydia vaccine shows promise in phase I studies

A vaccine to protect against the common sexually transmitted infection (STI) chlamydia was found safe and showed promising signs of being effective, reported a recent clinical trial. The research was published in The Lancet Infectious Diseases.

The preliminary trial was carried out on 35 healthy women. The researchers found that the vaccine provoked an immune response in these subjects.

“The findings are encouraging as they show the vaccine is safe and produces the type of immune response that could potentially protect against chlamydia,” said Professor Robin Shattock, from Imperial College London.

The study, led by Imperial College London and the Statens Serum Institut in Copenhagen, tested two different formulations of the vaccine to examine which would perform better.

Participants were injected on the first day of the trial, and then again on days 28 and 112, with boosters on days 126 and 140.

All of the vaccinated women — 30 out of 30 — showed an immune response. None of the women in the placebo group had such a response.

One of the vaccine variants, however, produced nearly six times more antibodies than the other, and has been chosen for the next round of testing.

Chlamydia is the most common bacterial STI in the world and can lead to infertility, as well as complications such as ectopic pregnancy, arthritis and increased susceptibility to other STIs such as HIV.

“The major issue with chlamydia is the long-term consequences,” said Professor Shattock.

“It is very treatable if identified, but as many people don’t have symptoms it can be missed, and the biggest problem is that it can go on to cause infertility in women.”

The infection is currently treated with antibiotics, and has the chances of recurrence. As many as three out of four cases show no symptoms.

“One of the problems we see with current efforts to treat chlamydia is that despite a very big screening, test and treat programme, people get repeatedly re-infected. If you could introduce a protective vaccine, you could break that cycle.”said Prof. Shattock.

Further trials will soon be carried out to determine whether it can fully protect against the infection, says the study.

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