World's first vaccine for the STD is in form of nose spray and shows promising results

The first vaccine to protect against the sexually transmitted disease chlamydia has shown promising results, experts have revealed.

The infection, which is often devoid of any obvious symptoms, impacts around 113 million people across the world each year and can render sufferers infertile.

Currently there are no direct preventative methods, other than advising people have safe, protected sex.

But now, a team of scientists at McMaster University, have developed what is believed to be the first widely protective vaccine against chlamydia.

Their tests reveal the antigen, known as BD584 is a potential vaccine candidate for the most common species of chlamydia - Chlamydia trachomatis.

Dr David Bulir, co-author of the study, said the vaccine to prevent the STD would 'extremely beneficial', because of the various side effects.

As most C.trachomatis infections are asymptomatic, chlamydia can often go untreated and lead to upper genital tract infections, pelvic inflammatory disease, and in severe cases, infertility.

Dr Bulir said: 'Vaccine development efforts in the past three decades have been unproductive and there is no vaccine approved for use in humans.

'Vaccination would be the best way to prevent a chlamydia infection, and this study has identified important new antigens which could be used as part of a vaccine to prevent or eliminate the damaging reproductive consequences of untreated infections.' 

The potential vaccine under development would be administered via a nasal spray.

The researchers found that the antigen, BD584 was able to reduce chlamydial shedding - a symptom of C.trachomatis - by 95 per cent.

The vaccine was also found to reduce another symptom, which involves Fallopian tubes becoming blocked with fluid, by 87.5 per cent.

Senior author, Professor James Mahony, from McMaster's Michael G. DeGroote School of Medicine hailed the results are promising.

Co-author and PhD student, Steven Liang, explained: 'Not only is the vaccine effective, it also has the potential to be widely protective against all C.trachomatis strains, including those that cause trachoma.'

Trachoma is an eye infection caused by chlamydia and is the leading cause of preventable blindness affecting millions of people in may resource-poor regions of the world.

Mr Liang added: 'The vaccine would be administered through the nose.

'This is easy and painless and does not require highly-trained health professionals to administer, and that makes it an inexpensive solution for developing nations.'

The next step is for further tests of the vaccine's effectiveness against different strains of chlamydia, and in different fomulations.

The study, which was funded by the Canadian Institutes for Health Research, is published in the journal Vaccine.  

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