An introduction to this common bacterial infection causing severe health issues and discernment from the vaccination progress for safety screening, suggesting Phase II of the clinical trial
This story does not include health advice. It is for information, inspiration, and awareness purposes.
Writing or talking about sexually transmitted infections (STIs) might not be fun and pleasant as it is a taboo topic in some cultures. However, as a scientist and health advocate, I don’t see an issue with discussing sexual health and feel obliged to create awareness as STIs are severe public health and economic concerns. I aim to provide valuable perspectives and updates from credible sources based on my years of research for good reasons.
CDC’s 2022 STI Surveillance Report highlights that STIs must be a public health priority as more than 2.5 million cases of chlamydia, gonorrhea, and syphilis were reported in the United States.
A 2015 meta-analysis informs that educational programs for preventing sexually transmitted infections have often been implemented in different settings and populations. Properly designed interventions can achieve a 30% reduction in STI incidence.
My interest in STIs started with neuroHIV and neurosyphilis, which are viral infections and can affect the brain and the nervous system, leading to cognitive decline and impairment if not treated timely. I wrote about neuroHIV on NewsBreak before.
I also reviewed chlamydia pneumonia, a bacterial infection usually transmitted through respiratory droplets (coughs or sneezes). It is a severe respiratory problem because it is associated with infections in the central nervous system and is linked to Alzheimer’s disease.
However, in this story, I only cover chlamydia trachomatis, which affects the genital tract and is a sexually transmitted infection (STI).
STIs are infections that are spread through sexual activity. In the old literature, they were called diseases. The term infection is now used because it encompasses a broader range of conditions, like those that may not always result in disease symptoms.
Bacteria, viruses, or parasites can cause these infections and affect people of all ages, backgrounds, and sexual orientations. According to WHO, more than 30 different bacteria, viruses, and parasites are known to be transmitted through sexual contact.
WHO states, “Eight pathogens are linked to the greatest incidence of STIs. Of these, four are currently curable: syphilis, gonorrhea, chlamydia, and trichomoniasis. The other four are incurable viral infections: hepatitis B, herpes simplex virus, HIV, and human papillomavirus.”
In this post, I only cover chlamydia trachomatis, a bacterial infection, as I want to update you on a promising clinical trial. As documented by this NIH book chapter, it is the most common sexually transmitted infection globally and in the US. It causes an ocular (eye) infection called trachoma.
I want to highlight trachoma, an eye disease caused by infection with Chlamydia. According to WHO, it is a public health problem in 42 countries and is responsible for blindness or visual impairment in about 1.9 million people.
An Overview of Chlamydia Trachomatis: Impact and Implications
As documented in the literature, chlamydia can affect both women and men, with different symptoms and potential complications.
In women, the cervix is commonly infected, causing health concerns like cervicitis, urethritis, pelvic inflammatory disease, perihepatitis (Fitz-Hugh-Curtis Syndrome), or proctitis. In men, chlamydia infections can cause urethritis, epididymitis, prostatitis, or proctitis.
These health conditions, characterized by inflammation and associated symptoms like pain or discomfort, pose risks of complications necessitating prompt diagnosis and treatment to prevent further spread and mitigate long-term health consequences. Therefore, when suspected, timely checkups and treatments are essential.
During pregnancy, chlamydia infections in women pose risks to both mother and child. Untreated infections in women can increase the risk of infertility and ectopic pregnancy, resulting in high medical costs.
Both men and women infected with Chlamydia trachomatis may experience symptoms like conjunctivitis (eye problem), pharyngitis (inflammation of the mucous membranes), and lymphogranuloma venereum (infection of the genital area), a less common but serious condition characterized by enlarged lymph nodes or severe proctocolitis (inflammation of the rectum and colon).
According to CDC:
“chlamydia spreads through vaginal, anal, or oral sex with someone with the infection. Semen does not have to be present to get or spread the infection. Most people with the infection have no symptoms and do not seek testing. It is most common among young people. Two-thirds of new chlamydial infections occur among youth aged 15–24 years.”
After this background, I’d like to introduce the first promising clinical trial completed in Europe. It is important because there was no vaccine for chlamydia before.
Progress Update on the Safety Screening of the First Chlamydia Vaccine Clinical Trial
As reported by The Lancet in 2019, the phase 1, first-in-human, double-blind, parallel, randomized, placebo-controlled trial was done at Hammersmith Hospital in London, UK, in healthy women aged 19–45.
On 11 April 2024, a new paper in the Lancet informed that currently, no vaccine is available for the prevalent global pathogen Chlamydia trachomatis. So, as a screening follow up of the first clinical trial NCT03926728, they evaluated its safety and immune response.
Between February 17, 2020, and February 22, 2022, they screened 154 people, randomly selected 65 for the trial, and 60 completed it (including 34 women and 46 White participants with an average age of 26.8 years). One person stopped taking the medicine due to mild side effects, but there were no serious side effects.
Most side effects were mild or moderate, with only seven severe cases reported. All active vaccine groups showed a robust immune response, with no such response in the placebo group. The vaccine demonstrated promising results in generating antibodies and immune responses against Chlamydia.
Their findings from this screening indicate a chlamydia vaccine regimen against ocular trachoma and urogenital chlamydia for testing in phase 2 clinical trials.
Interestingly, another group of scientists, who published in Nature on 23 February 2024, informed that they finally demonstrated long-lasting immunity and protection of mice one year after vaccination. Based on the results obtained in their study, they propose further investigation of CTH522/CAF®01 in a phase IIb study.
According to a recent NBC News article:
“Since the research on the vaccine is in its early stages, many questions remain. Dr. Hilary Reno asked if it confers the ability to hold off infection with chlamydia. More specifically, if you have an infection, does it mean you’re more likely to have an asymptomatic infection? She said we don’t know that, and that’s what the next phase of studies would be.” So, we need to wait for phase II.
Conclusions and Takeaways
I wrote this short story because the first clinical trial of the chlamydia vaccine offers hope for combating a prevalent global health concern. Raising awareness for sexually transmitted infections is crucial, especially with the rise in incidence rates among young people.
Chlamydia, the most common bacterial STI, not only affects the genital tract but also poses risks of eye infections, which can lead to blindness. The complications of chlamydia, such as infertility and ectopic (outside its normal position) pregnancy in women, highlight the importance of timely diagnosis and treatment.
Completing the clinical trial and its follow-up screening, which evaluated the vaccine's safety and immune response, marks a significant milestone in STI research. Promising results, including a robust immune response without severe side effects, provide optimism for future vaccine development of this bacterial infection.
Additionally, recent findings demonstrating long-lasting immunity in mice further highlight the potential of this vaccine candidate. Continued research and potential phase II clinical studies offer hope for developing an effective vaccine against Chlamydia trachomatis, potentially reducing the burden of this widespread infection.
Until people wait for approved public vaccination, the CDC advises that anyone experiencing genital symptoms such as discharge, a burning sensation when urinating, or unusual sores or rash should refrain from having sex until they consult a healthcare provider.
In addition, the CDC recommends yearly chlamydia screening of all sexually active women younger than 25. They also recommend screening for older women with risk factors, like new or multiple partners or a sex partner who has a sexually transmitted infection.
The good news is that, as informed by the CDC, antibiotics can easily cure chlamydia. Patients treated with single-dose antibiotics should not have sex for seven days, and their symptoms are gone. This helps prevent the spreading of the infection to sex partners.
Safe sex is believed to be a sustainable solution for STIs.
For example, in this 2020 case study, approximately half of the participants were aware of safe sex and knew about STIs. There is a need to have comprehensive sexual education, particularly emphasizing family planning, STIs, and HIV/AIDS for all grades in schools.
Thank you for reading my perspectives. I wish you a healthy and happy life.