Chlamydia jab could end UK's most common STI infection

Henrietta Strickland
August 13, 2019

Professor Robin Shattock, Head of Mucosal Infection and Immunity within the Department of Infectious Disease at Imperial 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".

Chlamydia, caused by the bacterium Chlamydia trachomatis, presents a major global health burden - with 131 million new cases occurring annually.

As many as three in four cases show no symptoms, leading some to think they are not infected.

"Given the impact of the chlamydia epidemic on women's health, reproductive health, infant health through vertical transmission, and increased susceptibility to other sexually transmitted diseases, a global unmet medical need exists for a vaccine against genital chlamydia", study author Peter Anderson from the Statens Serum Institut in Denmark said in a statement.

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.

"In the same way that HPV is a sexually transmitted infection, but people are motivated to get vaccinated because they want protection from cancer, we would anticipate that this would be positioned as a fertility vaccine", he says.

Researchers discovered the vaccine triggered an immune response during preliminary tests on 35 women. This can result in chronic pelvic pain and even infertility or ectopic pregnancy, especially in the developing world, where access to treatment and screening is limited. Thus, it is this version of the vaccine the researchers hope to take to the next stage.

Dr Shattock continued: "The major issue with chlamydia is the long-term consequences".

If the "phase two" trials are successful, scientists would then set up a final round of tests. In the small trial, about 30 healthy women ages 19 to 45 received doses of one of two experimental chlamydia vaccines, while five were given a placebo.

The vaccine was administered with three injections (on day 0, 28, and 112) and two intranasal boosts (on day 126 and 140).

Both formulations caused an immune response, but the one containing extra CAF01 liposomes produced 560 percent more antibodies. "Although clinical vaccine testing for chlamydia is in its infancy, this trial suggests optimism for the future". The most common local reactions were injection-site pain, tenderness, and movement impairment, with 88-93% of events being reported as mild in each of the groups, lasting a median of 2-4 days in all groups.

The research was made possible through grants from the European Commission.

"Increasingly vaccine development requires multiple partners", said Professor Shattock. "We have a wealth of world-leading expertise in the United Kingdom, with our scientists working to tackle infections, and to discover and develop new vaccines". But if we are no longer part of that European network we may be left behind.

This article is based on materials from The Lancet Infectious Diseases.

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