Chlamydia Vaccine Passes Safety Test In First Ever Human Trial

Maricruz Casares
Agosto 13, 2019

He said the study suggested the injection could provide sufficient protection against chlamydia, without the need for the nasal spray.

Chlamydia is a major global health problem with 131 million cases occurring annually around the world.

Investigator Prof Robin Shattock said: "The findings are encouraging as they show the vaccine is safe and produces the type of immune response that could potentially protect against chlamydia".

For one in every six women infected with chlamydia, the infection travels up from the cervix and causes pelvic inflammatory disease.

National screening programmes and antibiotic treatment have failed to reduce infection rates, and the highest number of new cases are found in teenagers and young adults.

Researchers discovered the vaccine triggered an immune response during preliminary tests on 35 women. Without treatment, it can lead to a range of complications for men and women, including fertility issues and an increased risk of HIV. The researchers compared two different formulations-one with added CAF01 liposomes created to aid cellular immunity and one with aluminium hydroxide known for its ability to help produce antibodies-to examine which formulation would perform better.

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If all goes well, Shattock says the vaccine could be commercially available in some countries in as few as five to seven years, then make its way to less-developed regions. Of those receiving the vaccine, 15 participants received the vaccine combined with CAF01 liposomes (CTH522:CAF01), and the other 15 received the vaccine with aluminium hydroxide (CTH522:AH). All received three injections into their arm muscle over four months, followed by two doses administered through a nasal spray in the weeks after.

Both formulations of the vaccine provoked an immune response in 100% of participants, whereas no participants in the placebo group achieved an immune response.

While both formulations of the vaccines were found to provoke an immune response, CTH522:CAF01 consistently performed better (producing 5.6 times more antibodies), so the authors suggest this formulation should be pursued for further clinical development. "We see the antibodies as a first line of defence", he said.

Although the vaccine provokes an immune response, whether this translates into protective immunity remains unclear. "To have a real public-health impact, you need to have something that just prevents infection, and that's what a vaccine would be created to do", says Lancet study co-author Robin Shattock, a professor of mucosal infection and immunity at Imperial College London. There were no related serious adverse events reported. Thirty-two women received all five jabs.

"A vaccine for prevention of C trachomatis infection would have enormous public health and economic impact", Toni Darville from the University of North Carolina wrote in a linked comment.

In the latest trial, researchers compared two different formulations of the new vaccine to examine which would perform better.

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