Article

Toward global prevention of sexually transmitted infections (STIs): The need for STI vaccines

Vaccine (Impact Factor: 3.49). 02/2014; 32(14). DOI: 10.1016/j.vaccine.2013.07.087
Source: PubMed

ABSTRACT An estimated 499 million curable sexually transmitted infections (STIs; gonorrhea, chlamydia, syphilis, and trichomoniasis) occurred globally in 2008. In addition, well over 500 million people are estimated to have a viral STI such as herpes simplex virus type 2 (HSV-2) or human papillomavirus (HPV) at any point in time. STIs result in a large global burden of sexual, reproductive, and maternal-child health consequences, including genital symptoms, pregnancy complications, cancer, infertility, and enhanced HIV transmission, as well as important psychosocial consequences and financial costs. STI control strategies based primarily on behavioral primary prevention and STI case management have had clear successes, but gains have not been universal. Current STI control is hampered or threatened by several behavioral, biological, and implementation challenges, including a large proportion of asymptomatic infections, lack of feasible diagnostic tests globally, antimicrobial resistance, repeat infections, and barriers to intervention access, availability, and scale-up. Vaccines against HPV and hepatitis B virus offer a new paradigm for STI control. Challenges to existing STI prevention efforts provide important reasons for working toward additional STI vaccines. We summarize the global epidemiology of STIs and STI-associated complications, examine challenges to existing STI prevention efforts, and discuss the need for new STI vaccines for future prevention efforts.

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    • "Meeting participants agreed that pursuit of a chlamydia vaccine is important, because of the substantial prevalence of chlamydial infection throughout the world [8], the link with adverse outcomes such as tubal-factor infertility, and the difficulty and expense of chlamydia control using current opportunistic screening strategies [9]. Chlamydia is a global problem, but the prevalence of chlamydia has been much better described in high-income than low-income countries. "
    Vaccine 03/2014; 32(14):1630–1637. DOI:10.1016/j.vaccine.2014.01.053 · 3.49 Impact Factor
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    • "Gonorrhea could soon become untreatable. Based on this observation, the development of STI vaccines could have an important impact on public health [1]. Vaccine development is a long and complex process driven by various forces and involving a large number of partners from various sectors and disciplines. "
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    ABSTRACT: Several barriers limit the development of vaccines against sexually transmitted diseases (STIs). Critical scientific information is missing that makes the feasibility and the likelihood of success of vaccines against genital herpes, chlamydia, gonorrhea and trichomonas uncertain: the immunity induced by natural infection is absent or imperfect which seriously limits the capacity to define the types of immune responses that an effective vaccine must induce. Reliable animal models are lacking and a number of crucial clinical questions are still unanswered about the goal of these vaccines and definition of endpoints for clinical trials. In the absence of a clear recognition of the need for vaccines against these diseases, there is no motivation for public or private research and industry to invest in the development of vaccines against STIs. The STI burden should be evaluated not only in terms of mortality and morbidity, but also in terms of economic and psycho-social impact. A global public-private consortium could mobilize the joint efforts of all stakeholders involved in the research, development and implementation of STI vaccines of the public and private sectors; ensure that sufficient resources are applied to R&D of vaccines against these STIs; and provide the pull-push forces that are necessary to overcome the barriers to develop safe and effective vaccines against these diseases.
    Vaccine 08/2013; 32(14). DOI:10.1016/j.vaccine.2013.08.032 · 3.49 Impact Factor
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    • "Potential interventions for reducing the incidence of infection and disease sequelae associated with Chlamydia include; (i) educational-based behaviour change promotion (e.g. increasing condom use or reducing partner numbers); (ii) increased screening, treatment and contact tracing/partner notification; (iii) the development of new biomedical prevention or therapeutic technologies (such as vaccines) (see review by Gottlieb et al. in this issue) [15]. However, it is not feasible to implement behaviour change campaigns to a sufficient scale and efficacy to result in population-level impacts. "
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    ABSTRACT: Chlamydia trachomatis continues to be the most commonly reported sexually transmitted bacterial infection in many countries with more than 100 million new cases estimated annually. These acute infections translate into significant downstream health care costs, particularly for women, where complications can include pelvic inflammatory disease and other disease sequelae such as tubal factor infertility. Despite years of research, the immunological mechanisms responsible for protective immunity versus immunopathology are still not well understood, although it is widely accepted that T cell driven IFN-g and Th17 responses are critical for clearing infection. While antibodies are able to neutralize infections in vitro, alone they are not protective, indicating that any successful vaccine will need to elicit both arms of the immune response. In recent years, there has been an expansion in the number and types of antigens that have been evaluated as vaccines, and combined with the new array of mucosal adjuvants, this aspect of chlamydial vaccinology is showing promise. Most recently, the opportunities to develop successful vaccines have been given a significant boost with the development of a genetic transformation system for Chlamydia, as well as the identification of the key role of the chlamydial plasmid in virulence. While still remaining a major challenge, the development of a successful C. trachomatis vaccine is starting to look more likely.
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