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Potential Chlamydia Vaccination

In this series of articles, medical students from across the country will share their knowledge and insight of medical physiology, anatomy and biochemistry to give you a taster of medical school. This will be a fantastic opportunity to build upon your A-Level Knowledge.

These articles give you a basic overview of the principles; we have attached videos and useful websites to develop a more detailed insight.

Chlamydia is one of the most common sexually transmitted diseases (STI’s) among younger people. It is mainly symptomless, with 70% of females and 50% of males not having any obvious signs. However, it can be very serious if not detected. It is more common in females than in males.

Chlamydia trachomatis is a gram-negative non-motile bacterium. It is 0.3-1 micrometres in diameter. If symptoms are present, for females, they will be dysuria (painful urination), bleeding after sex or between periods, increased vaginal discharge and lower abdominal pain. For males, they will be dysuria, white/cloudy discharge from tip of penis, burning or itching in the urethra and pain in the testicles. When detected, the most common drug that is prescribed is azithromycin, which is a protein synthesis inhibitor antibiotic.

However, if this disease is not detected, it can affect fertility in males and females. For males it can progress to epididymo-orchitis, which is inflammation of the testicles and the epididymis, which is where sperm is stored. This can cause infertility in males. Females can develop a disease called pelvic inflammatory disease.

Simple columnar epithelium normally lines the fallopian tubes. These cilia help to waft the egg, or oocyte, towards the womb. There are also secretory cells which secrete a watery secretion to nourish the oocyte. In pelvic inflammatory disease, chlamydia can destroy the cilia and so the oocyte/zygote cannot be passed down the tube as effectively. This can cause ectopic pregnancies to become more common, which is when the oocyte implants in the fallopian tube, or infertility. Therefore, if we had a vaccine for chlamydia, these issues would not occur and the population would be more healthy as a whole.

The research and the trial were run by researchers from Imperial College London and the Statens Serum Institut in Denmark. In total, 35 women took part in the trial – before the trial, they were tested negative for all STI’s and had a regular BMI. The group of women was split into a placebo group (a placebo is a dummy treatment) and a group who would receive the actual vaccine. The trial was double blind, which means neither the patient nor the researcher knew which they had been given to remove bias. Over 5 months, all women received 5 doses of the placebo or the vaccine. During this time, the 15 women who had been given the actual vaccine had started to produce antibodies against the chlamydia bacterium, suggesting that the vaccine works, however more trials need to be conducted. After all, this trial only included 35 women – it must be tested on a wider scale first.

More research is needed to find out more about the quantity and specificity of the antibodies produced. Although it was shown that antibodies were produced, would it be enough to fight off an infection or prevent someone from developing an infection? Is the amount of antibodies specific to chlamydia clinically relevant? Also how specific are these 'specific antibodies'? Are they only targeting the chlamydia bacteria, would they target other bacteria whether it be other STI's or affect bacteria elsewhere in the body? What are the side effects of taking the vaccination? Do the benefits outweigh the costs and risks?

This research brings about a lot of questions. Even if a vaccination for chlamydia was produced with a 90% success rate, is it ethical to have it as a treatment? Would people aware that there is a vaccination, be more likely to engage in unprotected sex? Would it lead to increased rates of unprotected sex and thus have a counterproductive effect? It is also worth noting that the vaccination was only specific to chlamydia and that there still a plethora of sexually transmitted illnesses. Should we be focusing our efforts on increasing the availability of condoms as opposed to funneling research into treating sexually transmitted illnesses? Is prevention better than the cure?