Effectiveness and impact of the 4CMenB vaccine against invasive serogroup B meningococcal disease and gonorrhoea in an infant, child, and adolescent programme: an observational cohort and case-control study

4CMenB journey to the 10-year anniversary and beyond

The 4-component meningococcal serogroup B (MenB) vaccine, 4CMenB, the first broadly protective, protein-based MenB vaccine to be licensed, is now registered in more than 50 countries worldwide. Real-world evidence (RWE) from the last decade confirms its effectiveness and impact, with infant immunization programs showing vaccine effectiveness of 71-95% against invasive MenB disease and cross-protection against non-B serogroups, including a 69% decrease in serogroup W cases in 4CMenB-eligible cohorts in England. RWE from different countries also demonstrates the potential for additional moderate protection against gonorrhea in adolescents. The real-world safety profile of 4CMenB is consistent with prelicensure reports. Use of the endogenous complement human serum bactericidal antibody (enc-hSBA) assay against 110 MenB strains may enable assessment of the immunological effectiveness of multicomponent MenB vaccines in clinical trial settings. Equitable access to 4CMenB vaccination is required to better protect all age groups, including older adults, and vulnerable groups through comprehensive immunization policies.

Profiling IgG and IgA antibody responses during vaccination and infection in a high-risk gonorrhoea population

Development of a vaccine against gonorrhoea is a global priority, driven by the rise in antibiotic resistance. Although Neisseria gonorrhoeae (Ng) infection does not induce substantial protective immunity, highly exposed individuals may develop immunity against re-infection with the same strain. Retrospective epidemiological studies have shown that vaccines containing Neisseria meningitidis (Nm) outer membrane vesicles (OMVs) provide a degree of cross-protection against Ng infection. We conducted a clinical trial (NCT04297436) of 4CMenB (Bexsero, GSK), a licensed Nm vaccine containing OMVs and recombinant antigens, comprising a single arm, open label study of two doses with 50 adults in coastal Kenya who have high exposure to Ng. Data from a Ng antigen microarray established that serum IgG and IgA reactivities against the gonococcal homologs of the recombinant antigens in the vaccine peaked at 10 but had declined by 24 weeks. For most reactive OMV-derived antigens, the reverse was the case. A cohort of similar individuals with laboratory-confirmed gonococcal infection were compared before, during, and after infection: their reactivities were weaker and differed from the vaccinated cohort. We conclude that the cross-protection of the 4CMenB vaccine against gonorrhoea could be explained by cross-reaction against a diverse selection of antigens derived from the OMV component.

Review of mathematical models of Neisseria gonorrhoeae vaccine impact: Implications for vaccine development

An effective prophylactic vaccine for prevention of Neisseria gonorrhoeae infection would have a major impact on sexual and reproductive health worldwide. Interest in developing gonorrhoea vaccines is growing due to the reported high rates of N. gonorrhoeae infections globally, and the threat of antimicrobial resistance. Several gonorrhoea vaccine candidates are currently under evaluation and various mathematical models have been used to assess the potential population-level impact a gonorrhoea vaccine may have once available. Here we review key aspects of gonorrhoea vaccine mathematical modelling studies, including model structures, populations considered, and assumptions used as well as vaccine characteristics and implementation scenarios investigated. The predicted vaccine impact varied between studies, ranging from as little as ∼17 % reduction in N. gonorrhoeae prevalence after 30 years up to 100 % reduction after 5 years. However, all studies predicted that even a partially effective gonorrhoea vaccine could have a substantial impact in reducing N. gonorrhoeae prevalence or incidence, particularly when high coverage is achieved within either important risk groups or the overall sexually active population. As expected, higher vaccine efficacy against acquisition of N. gonorrhoeae and longer duration of protection were linked to greater reductions in infections. A vaccine that alters onward transmission could also substantially reduce infections. Several gaps and research needs have been identified by researchers in the field and via this narrative literature review. For example, future modelling to inform gonorrhoea vaccine development and implementation should consider additional populations that are at high risk of N. gonorrhoeae infection, especially in low- and middle-income settings, as well as the impact of vaccination on the potential adverse sexual and reproductive health outcomes of infection. In addition, more detailed and robust epidemiological, biological, and behavioural data is needed to enable more accurate and robust modelling of gonorrhoea vaccine impact to inform future scientific and public health decision-making.

Vaccine value profile for Neisseria gonorrhoeae

Neisseria gonorrhoeae infection (gonorrhoea) is a global public health challenge, causing substantial sexual and reproductive health consequences, such as infertility, pregnancy complications and increased acquisition or transmission of HIV. There is an urgency to controlling gonorrhoea because of increasing antimicrobial resistance to ceftriaxone, the last remaining treatment option, and the potential for gonorrhoea to become untreatable. No licensed gonococcal vaccine is available. Mounting observational evidence suggests that N. meningitidis serogroup B outer membrane vesicle-based vaccines may induce cross-protection against N. gonorrhoeae (estimated 30%-40% effectiveness using the 4CMenB vaccine). Clinical trials to determine the efficacy of the 4CMenB vaccine against N. gonorrhoeae are underway, as are Phase 1/2 studies of a new gonococcal-specific vaccine candidate. Ultimately, a gonococcal vaccine must be accessible, affordable and equitably dispensed, given that those most affected by gonorrhoea are also those who may be most disadvantaged in our societies, and most cases are in less-resourced settings. This vaccine value profile (VVP) provides a high level, holistic assessment of the current data to inform the potential public health, economic and societal value of pipeline vaccines. This was developed by a working group of subject matter experts from academia, non-profit organizations, public private partnerships and multi-lateral organizations. All contributors have extensive expertise on various elements of the N. gonorrhoeae VVP and collectively aimed to identify current research and knowledge gaps. The VVP was developed using published data obtained from peer-reviewed journals or reports.

Vaccine effectiveness and impact of meningococcal vaccines against gonococcal infections: A systematic review and meta-analysis

OBJECTIVES

To systematically review and synthesis the evidence of vaccine effectiveness (VE) and impact (VI) of meningococcal vaccines in preventing gonorrhoea.

METHODS

We systematically evaluated studies. Literature searches were conducted in PubMed, Embase, Cochrane Library, CINAHL, Google Scholar, clinical trial registries, and major health and immunisation conferences. Meta-analysis was performed with the DerSimonian-Laird random-effects model to estimate the pooled VE.

RESULTS

Twelve studies met the criteria for inclusion. VE of meningococcal B (MenB) outer membrane vesicle (OMV) vaccines was evaluated in nine studies, with one study evaluating a non-OMV vaccine, MenB-FHbp. The majority of studies targeted individuals aged 15-30 years. Adjusted VE for OMV vaccines against gonorrhoea ranged from 22% to 46%. MenB-FHbp did not show protection against gonorrhoea. The pooled VE estimates of OMV vaccines against any gonorrhoea infection following the full vaccine series were 33-34%. VI was assessed for 4CMenB in Canada and Australia, for VA-MENGOC-BC in Cuba; and for MenBvac in Norway. VI ranged from a 30% to 59% reduction in gonorrhoea incidence.

CONCLUSIONS

4CMenB and other MenB-OMV vaccines show moderate effectiveness against gonorrhoea. Further research is required to explore the factors associated with vaccine protection, informing more effective vaccination strategies for the management of gonococcal infections.

Antimicrobial Resistance in Gonorrhea

Antimicrobial resistance is a global public health emergency. The World Health Organization recently highlighted the growing number of new sexually transmitted infections such as gonorrhea, syphilis, and Chlamydia, which are resistant to common antibiotics. The phenomenon is also on the rise due to increasing intercontinental travel. Emerging antibiotic-resistant strains of gonorrhea are particularly associated with international spread from Southeast Asian travelers. Infection with Neisseria gonorrhoeae can cause a wide spectrum of associated diseases such as dermatitis, arthritis and septic arthritis, and pelvic inflammatory disease, and can even lead to serious health consequences for the individual. Natural infection confers no immunity, and vaccination is not available currently, although in several countries, it has been reported that the antimeningococcal vaccine may protect against gonorrhea. Implementing all necessary preventive measures is crucial, as well as appropriate and timely diagnostic methods and effective antimicrobial therapeutic treatments in the correct modalities to avoid the increase of forms of gonorrhea that are resistant to common antibiotics and difficult to eradicate.

A Qualitative Concept Elicitation Study to Understand Patient-Reported Symptoms and Impacts of Neisseria gonorrhoeae Infections in the United States

BACKGROUND

Gonorrhea is the second most common bacterial sexually transmitted infection in the United States, with rising rates. Emerging antimicrobial resistance threatens public health, and vaccines are in development. This study documents patient-reported gonorrhea symptoms and health-related quality-of-life (HRQoL) impact in women who have sex with men (WSM), men who have sex with women (MSW), and men who have sex with men (MSM).

METHODS

Semistructured qualitative interviews were conducted (April 2021-March 2022) among US adults with recent (≤6 months) confirmed gonorrhea. Concept saturation was achieved, confirming adequate participant numbers to meet objectives. Elicited symptom and HRQoL impacts were used to develop a conceptual disease model. Common patient-reported outcome measure (PROM) items were compared with elicited concepts.

RESULTS

Thirty-two participants (15 WSM, 8 MSW, and 9 MSM) were included. Eight were asymptomatic, 6 had repeat infections, and 5 women and 4 men had complications (i.e., infertility or pelvic inflammatory disease, and urethritis, respectively).The most frequently reported symptoms were vaginal discharge (n = 11 of 12), dysuria (n = 10 of 12), and abdominal/vaginal pain (n = 9 of 12) for symptomatic WSM; dysuria (n = 5 of 6) and penile discharge (n = 4 of 6) for symptomatic MSW; and throat, testicular, or rectal pain (n = 4 of 6) for symptomatic MSM. All (symptomatic and asymptomatic) participants reported HRQoL impacts including negative emotional experiences (n = 31 of 32), and interference with sexual activity (n = 30 of 32), relationships (n = 24 of 32), and social life (n = 17 of 32). Concepts were poorly represented in existing PROMs.

CONCLUSIONS

Participants reported a diverse range of symptoms and HRQoL impacts, to help inform the value of new treatment and prevention options. More research is needed to quantify patient burden and develop PROMs.

Doxycycline prophylaxis and meningococcal group B vaccine to prevent bacterial sexually transmitted infections in France (ANRS 174 DOXYVAC): a multicentre, open-label, randomised trial with a 2 × 2 factorial design

BACKGROUND

Increased rates of sexually transmitted infections (STIs) are reported among men who have sex with men (MSM) and new interventions are needed. We aimed to assess whether post-exposure prophylaxis (PEP) with doxycycline could reduce the incidence of chlamydia or syphilis (or both) and whether the meningococcal group B vaccine (4CMenB) could reduce the incidence of gonorrhoea in this population.

METHODS

ANRS 174 DOXYVAC is a multicentre, open-label, randomised trial with a 2 × 2 factorial design conducted at ten hospital sites in Paris, France. Eligible participants were MSM aged 18 years or older, HIV negative, had a history of bacterial STIs within the 12 months before enrolment, and who were already included in the ANRS PREVENIR study (a cohort of MSM using pre-exposure prophylaxis with tenofovir and emtricitabine for HIV prevention). Participants were randomly assigned (2:1) to doxycycline PEP (two pills of 100 mg each orally within 72 h after condomless sex, with no more than three doses of 200 mg per week) or no PEP groups and were also randomly assigned (1:1) to the 4CMenB vaccine (GlaxoSmithKline, Paris, France; two intramuscular injections at enrolment and at 2 months) or no vaccine groups, using a computer-generated randomisation list with a permuted fixed block size of four. Follow-up occurred for at least 12 months (with visits every 3 months) up to 24 months. The coprimary outcomes were the risk of a first episode of chlamydia or syphilis (or both) after the enrolment visit at baseline for the doxycycline intervention and the risk of a first episode of gonorrhoea starting at month 3 (ie, 1 month after the second vaccine dose) for the vaccine intervention, analysed in the modified intention-to-treat population (defined as all randomly assigned participants who had at least one follow-up visit). This trial is registered with ClinicalTrials.gov, NCT04597424 (ongoing).

FINDINGS

Between Jan 19, 2021, and Sept 19, 2022, 556 participants were randomly assigned. 545 (98%) participants were included in the modified intention-to-treat analysis for the doxycycline PEP and no PEP groups and 544 (98%) were included for the 4CMenB vaccine and no vaccine groups. The median follow-up was 14 months (IQR 9-18). The median age was 40 years (34-48) and all 545 participants were male. There was no interaction between the two interventions (p≥0·1) for the primary outcome. The incidence of a first episode of chlamydia or syphilis (or both) was 8·8 per 100 person-years (35 events in 362 participants) in the doxycycline PEP group and 53·2 per 100 person-years (80 events in 183 participants) in the no PEP group (adjusted hazard ratio [aHR] 0·17 [95% CI 0·12-0·26]; p<0·0001). The incidence of a first episode of gonorrhoea, starting from month 3 was 58·3 per 100 person-years (103 events in 274 participants) in the 4CmenB vaccine group and 77·1 per 100 person-years (122 events in 270 participants) in the no vaccine group (aHR 0·78 [95% CI 0·60-1·01]; p=0·061). There were no deaths during the study. One drug-related serious adverse event (fixed-drug eruption) occurred in the doxycycline PEP group. Six (2%) participants in the doxycycline group discontinued doxycycline PEP because of gastrointestinal adverse events.

INTERPRETATION

Doxycycline PEP strongly reduced the incidence of chlamydia and syphilis in MSM, but we did not show efficacy of the 4CmenB vaccine for gonorrhoea. Doxycycline PEP should be assessed in other populations, such as heterosexual men and women, and its effect on antimicrobial resistance carefully monitored.

FUNDING

ANRS Maladies Infectieuses Emergentes.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

Comprehensive observational study evaluating the enduring effectiveness of 4CMenB, the meningococcal B vaccine against gonococcal infections in the Northern Territory and South Australia, Australia: study protocol

INTRODUCTION

The effectiveness of antibiotics for treating gonococcal infections is compromised due to escalating antibiotic resistance; and the development of an effective gonococcal vaccine has been challenging. Emerging evidence suggests that the licensed meningococcal B (MenB) vaccine, 4CMenB is effective against gonococcal infections due to cross-reacting antibodies and 95% genetic homology between the two bacteria, Neisseria meningitidis and Neisseria gonorrhoeae, that cause the diseases. This project aims to undertake epidemiological and genomic surveillance to evaluate the long-term protection of the 4CMenB vaccine against gonococcal infections in the Northern Territory (NT) and South Australia (SA), and to determine the potential benefit of a booster vaccine doses to provide longer-term protection against gonococcal infections.

METHODS AND ANALYSES

This observational study will provide long-term evaluation results of the effectiveness of the 4CMenB vaccine against gonococcal infections at 4-7 years post 4CMenB programme implementation. Routine notifiable disease notifications will be the basis for assessing the impact of the vaccine on gonococcal infections. Pathology laboratories will provide data on the number and percentage of N. gonorrhoeae positive tests relative to all tests administered and will coordinate molecular sequencing for isolates. Genome sequencing results will be provided by SA Pathology and Territory Pathology/New South Wales Health Pathology, and linked with notification data by SA Health and NT Health. There are limitations in observational studies including the potential for confounding. Confounders will be analysed separately for each outcome/comparison.

ETHICS AND DISSEMINATION

The protocol and all study documents have been reviewed and approved by the SA Department for Health and Well-being Human Research Ethics Committee (HREC/2022/HRE00308), and the evaluation will commence in the NT on receipt of approval from the NT Health and Menzies School of Health Research Human Research Ethics Committee. Results will be published in peer-reviewed journals and presented at scientific meetings and public forums.

Multicentre double-blind randomised placebo-controlled trial evaluating the efficacy of the meningococcal B vaccine, 4CMenB (Bexsero), against Neisseria gonorrhoeae infection in men who have sex with men: the GoGoVax study protocol

INTRODUCTION

Gonorrhoea, the sexually transmissible infection caused by Neisseria gonorrhoeae, has a substantial impact on sexual and reproductive health globally with an estimated 82 million new infections each year worldwide. N. gonorrhoeae antimicrobial resistance continues to escalate, and disease control is largely reliant on effective therapy as there is no proven effective gonococcal vaccine available. However, there is increasing evidence from observational cohort studies that the serogroup B meningococcal vaccine four-component meningitis B vaccine (4CMenB) (Bexsero), licensed to prevent invasive disease caused by Neisseria meningitidis, may provide cross-protection against the closely related bacterium N. gonorrhoeae. This study will evaluate the efficacy of 4CMenB against N. gonorrhoeae infection in men (cis and trans), transwomen and non-binary people who have sex with men (hereafter referred to as GBM+).

METHODS AND ANALYSIS

This is a double-blind, randomised placebo-controlled trial in GBM+, either HIV-negative on pre-exposure prophylaxis against HIV or living with HIV (CD4 count >350 cells/mm3), who have had a diagnosis of gonorrhoea or infectious syphilis in the last 18 months (a key characteristic associated with a high risk of N. gonorrhoeae infection). Participants are randomised 1:1 to receive two doses of 4CMenB or placebo 3 months apart. Participants have 3-monthly visits over 24 months, which include testing for N. gonorrhoeae and other sexually transmissible infections, collection of demographics, sexual behaviour risks and antibiotic use, and collection of research samples for analysis of N. gonorrhoeae-specific systemic and mucosal immune responses. The primary outcome is the incidence of the first episode of N. gonorrhoeae infection, as determined by nucleic acid amplification tests, post month 4. Additional outcomes consider the incidence of symptomatic or asymptomatic N. gonorrhoeae infection at different anatomical sites (ie, urogenital, anorectum or oropharynx), incidence by N. gonorrhoeae genotype and antimicrobial resistance phenotype, and level and functional activity of N. gonorrhoeae-specific antibodies.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the St Vincent's Hospital Human Research Ethics Committee, St Vincent's Hospital Sydney, NSW, Australia (ref: 2020/ETH01084). Results will be disseminated in peer-reviewed journals and via presentation at national and international conferences.

TRIAL REGISTRATION NUMBER

NCT04415424.

Belgian 2024 guidance on the use of pre-exposure prophylaxis

OBJECTIVES

We aimed to develop a guidance on the use of pre-exposure prophylaxis (PrEP) for HIV tailored to the Belgian context.

METHODS

Different aspects of PrEP care were judged by an expert group of nine Belgian clinicians, seeking consensus for areas of controversies.

RESULTS

PrEP should be considered in HIV negative patients at high risk of acquiring HIV. Currently, only oral tenofovir/emtricitabine is available in Belgium for PrEP, which can be used daily, or also event-driven in cisgender men and trans women who are not taking exogenous estradiol-based hormones. Personal counselling directed at medication adherence and sexual health should have a central role in PrEP care. At the initial assessment clinicians should give attention to symptoms of an acute HIV infection, the patients' immunization status and renal function. A regular follow-up must be set up to diagnose HIV seroconversion, treat sexually transmitted infections, and manage side effects of PrEP.

CONCLUSION

The Belgian guidance on the use of PrEP provides a point of reference for standard PrEP care in Belgium and will be periodically updated.

Neisseria gonorrhoeae vaccines: a contemporary overview

Neisseria gonorrhoeae infection is an important public health issue, with an annual global incidence of 87 million. N. gonorrhoeae infection causes significant morbidity and can have serious long-term impacts on reproductive and neonatal health and may rarely cause life-threatening disease. Global rates of N. gonorrhoeae infection have increased over the past 20 years. Importantly, rates of antimicrobial resistance to key antimicrobials also continue to increase, with the United States Centers for Disease Control and Prevention identifying drug-resistant N. gonorrhoeae as an urgent threat to public health. This review summarizes the current evidence for N. gonorrhoeae vaccines, including historical clinical trials, key N. gonorrhoeae vaccine preclinical studies, and studies of the impact of Neisseria meningitidis vaccines on N. gonorrhoeae infection. A comprehensive survey of potential vaccine antigens, including those identified through traditional vaccine immunogenicity approaches, as well as those identified using more contemporary reverse vaccinology approaches, are also described. Finally, the potential epidemiological impacts of a N. gonorrhoeae vaccine and research priorities for further vaccine development are described.

Neisseria gonorrhoeae lipooligosaccharide glycan epitopes recognized by bactericidal IgG antibodies elicited by the meningococcal group B-directed vaccine, MenB-4C

Introduction

Outer membrane vesicles (OMVs) of Neisseria meningitidis in the group B-directed vaccine MenB-4C (BexseroR) protect against infections with Neisseria gonorrhoeae. The immunological basis for protection remains unclear. N. meningitidis OMV vaccines generate human antibodies to N. meningitidis and N. gonorrhoeae lipooligosaccharide (LOS/endotoxin), but the structural specificity of these LOS antibodies is not defined.

Methods

Ten paired human sera obtained pre- and post-MenB-4C immunization were used in Western blots to probe N. meningitidis and N. gonorrhoeae LOS. Post-MenB-4C sera (7v5, 19v5, and 17v5), representing individual human variability in LOS recognition, were then used to interrogate structurally defined LOSs of N. meningitidis and N. gonorrhoeae strains and mutants and studied in bactericidal assays.

Results and discussion

Post-MenB-4C sera recognized both N. meningitidis and N. gonorrhoeae LOS species, ~10% of total IgG to gonococcal OMV antigens. N. meningitidis and N. gonorrhoeae LOSs were broadly recognized by post-IgG antibodies, but with individual variability for LOS structures. Deep truncation of LOS, specifically a rfaK mutant without α-, β-, or γ-chain glycosylation, eliminated LOS recognition by all post-vaccine sera. Serum 7v5 IgG antibodies recognized the unsialyated L1 α-chain, and a 3-PEA-HepII or 6-PEA-HepII was part of the conformational epitope. Replacing the 3-PEA on HepII with a 3-Glc blocked 7v5 IgG antibody recognition of N. meningitidis and N. gonorrhoeae LOSs. Serum 19v5 recognized lactoneotetrose (LNT) or L1 LOS-expressing N. meningitidis or N. gonorrhoeae with a minimal α-chain structure of Gal-Glc-HepI (L8), a 3-PEA-HepII or 6-PEA-HepII was again part of the conformational epitope and a 3-Glc-HepII blocked 19v5 antibody binding. Serum 17v5 LOS antibodies recognized LNT or L1 α-chains with a minimal HepI structure of three sugars and no requirement for HepII modifications. These LOS antibodies contributed to the serum bactericidal activity against N. gonorrhoeae. The MenB-4C vaccination elicits bactericidal IgG antibodies to N. gonorrhoeae conformational epitopes involving HepI and HepII glycosylated LOS structures shared between N. meningitidis and N. gonorrhoeae. LOS structures should be considered in next-generation gonococcal vaccine design.

The Diverse Spectrum of Invasive Meningococcal Disease in Pediatric and Adolescent Patients: Narrative Review of Cases and Case Series

INTRODUCTION

Invasive meningococcal disease (IMD) is a potentially life-threatening disease caused by Neisseria meningitidis infection. We reviewed case reports of IMD from newborns, infants, children, and adolescents, and described the real-life clinical presentations, diagnoses, treatment paradigms, and clinical outcomes.

METHODS

PubMed and Embase were searched for IMD case reports on patients aged ≤ 19 years published from January 2011 to March 2023 (search terms "Neisseria meningitidis" or "invasive meningococcal disease", and "infant", "children", "paediatric", pediatric", or "adolescent").

RESULTS

We identified 97 publications reporting 184 cases of IMD, including 25 cases with a fatal outcome. Most cases were in adolescents aged 13-19 years (34.2%), followed by children aged 1-5 years (27.6%), children aged 6-12 years (17.1%), infants aged 1-12 months (17.1%), and neonates (3.9%). The most common disease-causing serogroups were W (40.2%), B (31.7%), and C (10.4%). Serogroup W was the most common serogroup in adolescents (17.2%), and serogroup B was the most common in the other age groups, including children aged 1-5 years (11.5%). The most common clinical presentations were meningitis (46.6%) and sepsis (36.8%).

CONCLUSIONS

IMD continues to pose a threat to the health of children and adolescents. While this review was limited to case reports and is not reflective of global epidemiology, adolescents represented the largest group with IMD. Additionally, nearly half of the patients who died were adolescents, emphasizing the importance of monitoring and vaccination in this age group. Different infecting serogroups were predominant in different age groups, highlighting the usefulness of multivalent vaccines to provide the broadest possible protection against IMD. Overall, this review provides useful insights into real-life clinical presentations, treatment paradigms, diagnoses, and clinical outcomes to help clinicians diagnose, treat, and, ultimately, protect patients from this devastating disease.

Promising developments in gonococcal vaccines

PURPOSE OF REVIEW

While effective vaccines to prevent invasive infections by Neisseria meningitidis have been deployed around the world, development of a vaccine to prevent Neisseria gonorrhoeae has lagged. After multiple failed vaccine candidates, vaccine development for N. gonorrhoeae is showing promise for the first time in several decades. This review highlights recent progress in the field.

RECENT FINDINGS

Vaccines containing outer-membrane vesicles (OMV) have been used to manage outbreaks of the serogroup B N. meningitidis in a number of countries. Epidemiologic studies indicate these vaccination campaigns were associated with reductions in reported N. gonorrhoeae infections. Recently, a serogroup B N. meningitidis vaccine containing both recombinant antigens and OMV has been licensed through much of the world. Epidemiologic studies also demonstrate associations between 4CMenB immunization and reduced N. gonorrhoeae infections. Additionally, mathematical modeling studies have begun to identify potential strategies for vaccine deployment to maximize reduction of infections.

SUMMARY

After several decades with little progress towards an effective gonococcal vaccine, large observational studies have provided evidence that a new generation of group B N. meningitidis vaccines containing OMV have serendipitously restarted the field. Ongoing clinical trials will soon provide definitive evidence regarding the efficacy of these vaccines in preventing N. gonorrhoeae infection.

The important lessons lurking in the history of meningococcal epidemiology

INTRODUCTION

The epidemiology of invasive meningococcal disease (IMD), a rare but potentially fatal illness, is typically described as unpredictable and subject to sporadic outbreaks.

AREAS COVERED

Meningococcal epidemiology and vaccine use during the last ~ 200 years are examined within the context of meningococcal characterization and classification to guide future IMD prevention efforts.

EXPERT OPINION

Historical and contemporary data highlight the dynamic nature of meningococcal epidemiology, with continued emergence of hyperinvasive clones and affected regions. Recent shifts include global increases in serogroup W disease, meningococcal antimicrobial resistance (AMR), and meningococcal urethritis; additionally, unvaccinated populations have experienced disease resurgences following lifting of COVID-19 restrictions. Despite these changes, a close analysis of meningococcal epidemiology indicates consistent dominance of serogroups A, B, C, W, and Y and elevated IMD rates among infants and young children, adolescents/young adults, and older adults. Demonstrably effective vaccines against all 5 major disease-causing serogroups are available, and their prophylactic use represents a powerful weapon against IMD, including AMR. The World Health Organization's goal of defeating meningitis by the year 2030 demands broad protection against IMD, which in turn indicates an urgent need to expand meningococcal vaccination programs across major disease-causing serogroups and age-related risk groups.

Preclinical efficacy of a cell division protein candidate gonococcal vaccine identified by artificial intelligence

IMPORTANCE

Vaccines to curb the global spread of multidrug-resistant gonorrhea are urgently needed. Here, 26 vaccine candidates identified by an artificial intelligence-driven platform (Efficacy Discriminative Educated Network[EDEN]) were screened for efficacy in the mouse vaginal colonization model. Complement-dependent bactericidal activity of antisera and the EDEN protective scores both correlated positively with the reduction in overall bacterial colonization burden. NGO1549 (FtsN) and NGO0265, both involved in cell division, displayed the best activity and were selected for further development. Both antigens, when fused to create a chimeric protein, elicited bactericidal antibodies against a wide array of gonococcal isolates and significantly attenuated the duration and burden of gonococcal colonization of mouse vaginas. Protection was abrogated in mice that lacked complement C9, the last step in the formation of the membrane attack complex pore, suggesting complement-dependent bactericidal activity as a mechanistic correlate of protection of the vaccine. FtsN and NGO0265 represent promising vaccine candidates against gonorrhea.

Benefits of Combining Molecular Biology and Controlled Human Infection Model Methodologies in Advancing Vaccine Development

Infectious diseases continue to account for a significant portion of global deaths despite the use of vaccines for several centuries. Immunization programs around the world are a testament to the great success of multiple vaccines, yet there are still diseases without vaccines and others that require safer more effective ones. Addressing uncontrolled and emerging disease threats is restrained by the limitations and bottlenecks encountered with traditional vaccine development paradigms. Recent advances in modern molecular biology technologies have enhanced the interrogation of host pathogen interaction and deciphered complex pathways, thereby uncovering the myriad interplay of biological events that generate immune protection against foreign agents. Consequent to insights into the immune system, modern biology has been instrumental in the development and production of next generation 21st century vaccines. As these biological tools, commonly and collectively referred to as 'omics, became readily available, there has been a renewed consideration of Controlled Human Infection Models (CHIMs). Successful and reproducible CHIMs can complement modern molecular biology for the study of infectious diseases and development of effective vaccines in a regulated process that mitigates risk, cost, and time, with capacity to discern immune correlates of protection.

Evaluating vaccine-elicited antibody activities against Neisseria gonorrhoeae: cross-protective responses elicited by the 4CMenB meningococcal vaccine

The bacterial pathogen Neisseria gonorrhoeae is an urgent global health problem due to increasing numbers of infections, coupled with rampant antibiotic resistance. Vaccines against gonorrhea are being prioritized to combat drug-resistant N. gonorrhoeae. Meningococcal serogroup B vaccines such as four-component meningococcal B vaccine (4CMenB) are predicted by epidemiology studies to cross-protect individuals from natural infection with N. gonorrhoeae and elicit antibodies that cross-react with N. gonorrhoeae. Evaluation of vaccine candidates for gonorrhea requires a suite of assays for predicting efficacy in vitro and in animal models of infection, including the role of antibodies elicited by immunization. Here, we present the development and optimization of assays to evaluate antibody functionality after immunization of mice: antibody binding to intact N. gonorrhoeae, serum bactericidal activity, and opsonophagocytic killing activity using primary human neutrophils [polymorphonuclear leukocytes (PMNs)]. These assays were developed with purified antibodies against N. gonorrhoeae and used to evaluate serum from mice that were vaccinated with 4CMenB or given alum as a negative control. Results from these assays will help prioritize gonorrhea vaccine candidates for advanced preclinical to early clinical studies and will contribute to identifying correlates and mechanisms of immune protection against N. gonorrhoeae.

Th1-polarized MtrE-based gonococcal vaccines display prophylactic and therapeutic efficacy

ABSTRACTGlobal dissemination of high-level ceftriaxone-resistant Neisseria gonorrhoeae strains associated with the FC428 clone poses a threat to the efficacy ceftriaxone-based therapies. Vaccination is the best strategy to contain multidrug-resistant infections. In this study, we investigated the efficacy of MtrE and its surface Loop2 as vaccine antigens when combined with a Th1-polarizing adjuvant, which is expected to be beneficial for gonococcal vaccine development. Using in vitro dendritic cell maturation and T cell differentiation assays, CpG1826 was identified as the optimal Th1-polarizing adjuvant for MtrE and Loop2 displayed as linear epitope (Nloop2) or structural epitope (Intraloop2) on a carrier protein. Loop2-based antigens raised strongly Th1-polarized and bactericidal antibody responses in vaccinated mice. Furthermore, the vaccine formulations provided protection against a gonococcal challenge in mouse vaginal tract infection model when provided as prophylactic vaccines. Also, the vaccine formulations accelerated gonococcal clearance when provided as a single therapeutic dose to treat an already established infection, including against a strain associated with the FC428 clone. Therefore, this study demonstrated that MtrE and Loop 2 are effective gonococcal vaccine antigens when combined with the Th1-polarizing CpG1826 adjuvant.

Prevention strategies for sexually transmitted infections, HIV, and viral hepatitis in Europe

The current prevention efforts for STIs, HIV and viral hepatitis in the WHO European Region, especially in the Central and Eastern subregions, are hindered by healthcare disparities, data gaps, and limited resources. In this comprehensive narrative review, we aim to highlight both achievements and persisting challenges while also exploring new developments that could significantly impact the prevention of these infections in the near future. While pre-exposure prophylaxis (PrEP) for HIV has been broadly approved and implemented in 38 out of 53 countries in the region, challenges remain, including cost, limited licensing, and incomplete adherence. We explore innovative approaches like on-demand PrEP, long-acting injectable cabotegravir, and intravaginal rings that have shown promising results, alongside the use of six-monthly lenacapavir, the outcomes of which are pending. Additionally, the potential of doxycycline post-exposure prophylaxis has been discussed, revealing efficacy in reducing chlamydia and syphilis risk, but effectiveness against gonorrhoea being contingent on tetracycline resistance rates, and the need of further data to determine potential resistance development in other bacteria and its impact on the gut microbiome. We examine successful vaccination campaigns against HBV and HPV, the ongoing development of vaccines for chlamydia, syphilis, herpesvirus, and gonorrhoea, and challenges in HIV vaccine research, including lines of research with significant potential like sequential immunization, T-cell responses, and mRNA technology. This review underscores the research endeavors that pave the way for a more resilient and robust approach to combating STIs, HIV, and viral hepatitis in the region.

Meningococcal B Immunisation in Adults and Potential Broader Immunisation Strategies: A Narrative Review

Recombinant vaccines against invasive meningococcal disease due to Neisseria meningitidis serogroup B (MenB) have shown substantial impact in reducing MenB disease in targeted populations. 4CMenB targets four key N. meningitidis protein antigens; human factor H binding protein (fHbp), Neisserial heparin binding antigen (NHBA), Neisseria adhesin A (NadA) and the porin A protein (PorA P1.4), with one or more of these expressed by most pathogenic MenB strains, while MenB-FHbp targets two distinct fHbp variants. While many countries recommend MenB immunisation in adults considered at high risk due to underlying medical conditions or immunosuppression, there are no recommendations for routine use in the general adult population. We reviewed the burden of MenB in adults, where, while incidence rates remain low (and far lower than in young children < 5 years of age at greatest risk), a substantial proportion of MenB cases (20% or more) is now observed in the adult population; evident in Europe, Australia, and in the United States. We also reviewed immunogenicity data in adults from clinical studies conducted during MenB vaccine development and subsequent post-licensure studies. A 2-dose schedule of 4CMenB generates hSBA titres ≥ 1:4 towards all four key vaccine target antigens in up to 98-100% of subjects. For MenB-FHbp, a ≥ fourfold rise in hSBA titres against the four primary representative test strains was observed in 70-95% of recipients following a 3-dose schedule. While this suggests potential benefits for MenB immunisation if used in adult populations, data are limited (especially for adults > 50 years) and key aspects relating to duration of protection remain unclear. Although a broader adult MenB immunisation policy could provide greater protection of the adult population, additional data are required to support policy decision-making.

The potential impact of a vaccine on Neisseria gonorrhoeae prevalence among heterosexuals living in a high prevalence setting

BACKGROUND

Treatment of Neisseria gonorrhoeae is under threat with the emergence and spread of antimicrobial resistance. Thus, there is a growing interest in the development of a gonorrhoea vaccine. We used mathematical modelling to assess the impact of a hypothetical vaccine in controlling gonorrhoea among heterosexuals living in a setting of relatively high N. gonorrhoeae prevalence (∼3 %).

METHODS

We developed a mathematical model of N. gonorrhoeae transmission among 15-49-year-old heterosexuals, stratified by age and sex, and calibrated to prevalence and sexual behaviour data from South Africa as an example of a high prevalence setting for which we have data available. Using this model, we assessed the potential impact of a vaccine on N. gonorrhoeae prevalence in the entire population. We considered gonorrhoea vaccines having differing impacts on N. gonorrhoeae infection and transmission and offered to different age-groups.

RESULTS

The model predicts that N. gonorrhoeae prevalence can be reduced by ∼50 % in 10 years following introduction of a vaccine if annual vaccination uptake is 10 %, vaccine efficacy against acquisition of infection is 25 % and duration of protection is 5 years, with vaccination available to the entire population of 15-49-year-olds. If only 15-24-year-olds are vaccinated, the predicted reduction in prevalence in the entire population is 25 % with equivalent vaccine characteristics and uptake. Although predicted reductions in prevalence for vaccination programmes targeting only high-activity individuals and the entire population are similar over the same period, vaccinating only high-activity individuals is more efficient as the cumulative number of vaccinations needed to reduce prevalence in the entire population by 50 % is ∼3 times lower for this programme.

CONCLUSION

Provision of a gonorrhoea vaccine could lead to substantial reductions in N. gonorrhoeae prevalence in a high prevalence heterosexual setting, even with moderate annual vaccination uptake of a vaccine with partial efficacy.

Evaluating vaccine-elicited antibody activities against Neisseria gonorrhoeae: cross-protective responses elicited by the 4CMenB meningococcal vaccine

The bacterial pathogen Neisseria gonorrhoeae is an urgent global health problem due to increasing numbers of infections, coupled with rampant antibiotic resistance. Vaccines against gonorrhea are being prioritized to combat drug-resistant N. gonorrhoeae. Meningococcal serogroup B vaccines such as 4CMenB are predicted by epidemiology studies to cross-protect individuals from natural infection with N. gonorrhoeae and elicit antibodies that cross-react with N. gonorrhoeae. Evaluation of vaccine candidates for gonorrhea requires a suite of assays for predicting efficacy in vitro and in animal models of infection, including the role of antibodies elicited by immunization. Here we present assays to evaluate antibody functionality after immunization: antibody binding to intact N. gonorrhoeae, serum bactericidal activity, and opsonophagocytic killing activity using primary human neutrophils (polymorphonuclear leukocytes). These assays were developed with purified antibodies against N. gonorrhoeae and used to evaluate serum from mice that were vaccinated with 4CMenB or given alum as a negative control. Results from these assays will help prioritize gonorrhea vaccine candidates for advanced preclinical to early clinical study and will contribute to identifying correlates and mechanisms of immune protection against N. gonorrhoeae .

Four-Component Recombinant Protein-Based Vaccine Effectiveness Against Serogroup B Meningococcal Disease in Italy

Importance

Population-based data on the 4-component recombinant protein-based (4CMenB) vaccine effectiveness and reduction in incidence rate ratios (IRRs) are continuously needed to assess vaccine performance in the prevention of serogroup B invasive meningococcal disease (IMD).

Objective

To assess the effectiveness and reduction in IRRs associated with the 4CMenB vaccine in the pediatric population in 6 regions in Italy.

Design, Setting, and Participants

This retrospective cohort screening study and case-control study included data from children aged younger than 6 years in 6 highly populated Italian regions from January 1, 2006, to January 1, 2020. Participants included children younger than 6 years diagnosed with serogroup B IMD without predisposing factors. Data were collected from regional surveillance and vaccination registries and were analyzed from September 2021 to January 2022.

Exposures

Routine 4CMenB vaccination, per regional vaccination programs.

Main Outcomes and Measures

The main outcome was the effectiveness of the 4CMenB vaccine in the prevention of serogroup B IMD in the population of children aged younger than 6 years in 6 Italian regions. The percentages of vaccine effectiveness (VE) were obtained through the concomitant use of a screening method and a case-control study. Secondary outcomes were the comparison of effectiveness results obtained using the 2 different computational methods, the description of serogroup B IMD incidence rates, and reduction in IRRs before and after 4CMenB introduction, as a proxy for vaccine impact.

Results

The cohort screening study included a resident population of 587 561 children younger than 6 years in 3 regions with similar surveillance protocols, and the matched-case controls study assessed a resident population of 1 080 620 children younger than 6 years in 6 regions. Analyses found that 4CMenB VE in fully immunized children was 94.9% (95% CI, 83.1%-98.4%) using the screening method and 91.7% (95% CI, 24.4%-98.6%) using the case-control method. Overall reduction in IRR was 50%, reaching 70% in regions with early-start vaccination schedules. The case-control method involving 6 highly-populated Italian regions included 26 cases and 52 controls and found an estimated VE of 92.4% (95% CI, 67.6%-97.9%) in children old enough for the first vaccine dose and 95.6% (95% CI, 71.7%-99.1%) in fully immunized children. VE was more than 90% for partially immunized children. Even in regions where the first dose was administered at age 2 months, almost 20% of unvaccinated cases were among infants too young to receive the first 4CMenB dose.

Conclusions and Relevance

This screening cohort study and matched case-controls study found high effectiveness of 4CMenB vaccination and greater reduction in IRR for early-start vaccination schedules in preventing invasive serogroup B meningococcal disease. The high proportion of children too young to be vaccinated among unvaccinated cases suggests that starting the vaccination even earlier may prevent more cases. Screening and case-control methods provided similar estimates of VE: either method may be used in different study settings, but concomitant use can provide more robust estimates.

Association of Group B Meningococcal Vaccine Receipt With Reduced Gonorrhea Incidence Among University Students

This case-control study examines reported cases of gonorrhea among recipients of meningococcal group B vaccine at 2 universities in Oregon.

Challenges in Managing Gonorrhea and New Advances in Prevention

Gonorrhea is the second most common bacterial sexually transmitted infection in the United States. Rates are increasing, and multiple challenges compound management, including worsening antimicrobial resistance. New therapeutics, enhanced screening and partner notification, and treatment through point-of-care testing and expedited partner therapy, as well as primary prevention efforts provide opportunities for success in combating these trends.

Healthy Vaccinee Bias and MenB-FHbp Vaccine Effectiveness Against Gonorrhea

ABSTRACT

Observational studies demonstrated 30% to 40% effectiveness of outer-membrane vesicle (OMV) meningococcal serogroup B vaccines against gonorrhea. To explore whether healthy vaccinee bias influenced such findings, we examined the effectiveness of MenB-FHbp, a non-OMV vaccine that is not protective against gonorrhea. MenB-FHbp was ineffective against gonorrhea. Healthy vaccinee bias likely did not confound earlier studies of OMV vaccines.

4CMenB sustained vaccine effectiveness against invasive meningococcal B disease and gonorrhoea at three years post program implementation

OBJECTIVES

To evaluate persistence of vaccine effectiveness (VE) and vaccine impact (VI) on invasive meningococcal B (MenB) disease and gonorrhoea at three years after implementation of a state funded 4CMenB program for infants, children, adolescents and young people in South Australia.

METHODS

VI was assessed using a Poisson or negative binomial regression model, and VE was estimated using screening and case-control methods. Chlamydia controls were used to estimate VE in the primary analysis to control potential confounding effects such as high-risk sexual behaviour associated with sexually transmitted infections.

RESULTS

During the three-year program, reductions of 63.1% (95%CI 29.0% to 80.9%) and 78.5% (95%CI 33.0% to 93.1%) in incidence of MenB disease were observed in infants and adolescents, respectively. There were no cases in infants who had received three doses of 4CMenB. Two-dose VE against MenB disease was 90.7% (95%CI 6.9% to 99.1%) for the childhood program and 83.5% (95%CI 0 to 98.2%) for the adolescent program. Two-dose VE against gonorrhoea in adolescents was 33.2% (95%CI 15.9% to 47.0%). Lower VE estimates were demonstrated after 36 months post-vaccination (23.2% (95%CI 0 to 47.5%) >36 months post-vaccination compared to 34.9% (95%CI 15.0% to 50.1%) within 6-36 months). Higher VE estimates were found after excluding patients with repeat gonorrhoea infections (37.3%, 95%CI 19.8% to 51.0%). For gonorrhoea cases co-infected with chlamydia VE was maintained (44.7% (95%CI 17.1% to 63.1%).

CONCLUSION

The third-year evaluation results show persistent vaccine effectiveness of 4CMenB against MenB disease in infants and adolescents. As this is the first ongoing program for adolescents, moderate vaccine protection against gonorrhoea with waning effectiveness three years post-vaccination was demonstrated in adolescents and young adults. The additional protection of 4CMenB vaccine against gonorrhoea, likely through cross-protection should be considered in cost-effectiveness analyses. A booster dose may need to be further evaluated and considered in adolescents due to waning protection against gonorrhoea demonstrated after 36 months post-vaccination.

Meningococcus B Vaccination Effectiveness Against Neisseria gonorrhoeae Infection in People Living With HIV: A Case-Control Study

BACKGROUND

We assessed the vaccination effectiveness (VE) of multicomponent meningococcal serogroup B (4CMenB) vaccine against gonorrhea among people living with HIV (PLWH) with a previous diagnosis of sexually transmitted infection.

METHODS

Unmatched case-control study on men who have sex with men living with HIV, in care at San Raffaele Scientific Institute, Milan, Italy, with gonorrhea, syphilis, chlamydia, or anal human papillomavirus between July 2016 (beginning of 4CMenB vaccination) and February 2021 (date of freezing). For the analysis, cases were people with ≥1 gonorrhea infection since July 2016, and controls were people with ≥1 syphilis, chlamydia, or anal human papillomavirus infection since July 2016. Logistic regression was used to provide the estimate of 4CMenB VE against gonorrhea.

RESULTS

Included people living with HIV were 1051 (103 cases, 948 controls); 349 of 1051 (33%) received 2 doses of 4CMenB vaccination. The median follow-up was 3.8 years (2.1-4.3 years). The unadjusted estimate for VE against gonorrhea was 42% (95% confidence interval, 6%-64%; P = 0.027). Logistic regression showed that VE against gonorrhea remained significant (44%; 95% confidence interval, 9%-65%; P = 0.020) after adjusting for some factors that might have a potential influence on VE or those with significant unbalanced distributions between cases and controls at univariable analysis.

CONCLUSIONS

4CMenB vaccination is associated with a lower risk of gonorrhea in the setting of men who have sex with men living with HIV with a previous sexually transmitted infection.

OpcA and PorB are novel bactericidal antigens of the 4CMenB vaccine in mice and humans

The ability of Neisseria meningitidis Outer Membrane Vesicles (OMV) to induce protective responses in humans is well established and mainly attributed to Porin A (PorA). However, the contribution of additional protein antigens to protection remains to be elucidated. In this study we dissected the immunogenicity of antigens originating from the OMV component of the 4CMenB vaccine in mice and humans. We collected functional data on a panel of strains for which bactericidal responses to 4CMenB in infants was attributable to the OMV component and evaluated the role of 30 OMV-specific protein antigens in cross-coverage. By using tailor-made protein microarrays, the immunosignature of OMV antigens was determined. Three of these proteins, OpcA, NspA, and PorB, triggered mouse antibodies that were bactericidal against several N. meningitidis strains. Finally, by genetic deletion and/or serum depletion studies, we demonstrated the ability of OpcA and PorB to induce functional immune responses in infant sera after vaccination. In conclusion, while confirming the role of PorA in eliciting protective immunity, we identified two OMV antigens playing a key role in protection of infants vaccinated with the 4CMenB vaccine against different N. meningitidis serogroup B strains.

The Impact of Educational Intervention on Willingness to Enroll in a Clinical Trial of a Gonorrhea Vaccine

Globally, >80 million new gonorrhea infections occur annually. Here, we assessed barriers to and influences on participation in a gonorrhea clinical trial and the impact of educational intervention. The survey was fielded in the US in March 2022. Higher enrollment of Black/African Americans and younger individuals than represented in the US demographic distribution reflected the higher incidence of gonorrhea in these groups. Behavioral characteristics and baseline attitudes toward vaccination were collected. Participants were probed on their knowledge of and likelihood to enroll in general and gonorrhea vaccine trials. Participants hesitant to enroll in a gonorrhea vaccine trial were given nine bullets of basic facts about the disease and asked again to rank their likelihood to enroll. Overall, 450 individuals completed the survey. Fewer participants were willing (quite/very likely) to join a gonorrhea versus a general vaccine trial (38.2% [172/450] vs. 57.8% [260/450]). The likelihood to enroll in any vaccine trial or a gonorrhea vaccine trial was greater with higher self-declared knowledge (Spearman’s ρ = 0.277 [p < 0.001] and 0.316 [p < 0.001], respectively) and baseline openness towards vaccination (p < 0.001 for both). Self-declared awareness of gonorrhea was associated with age (p = 0.001), education (p = 0.031), and ethnicity/race (p = 0.002), with older, more educated, and Black/African Americans having higher awareness. Males (p = 0.001) and those with more sexual partners (p < 0.001) were more likely to enroll in a gonorrhea vaccine trial. Educational intervention had a significant (p < 0.001) impact on hesitancy. Improvement in willingness to enroll in a gonorrhea vaccine trial was greatest in those initially marginally hesitant and lowest in those initially strongly hesitant. Basic educational intervention has the potential to improve recruitment into gonorrhea vaccine trials.

The potential public health impact of adolescent 4CMenB vaccination on Neisseria gonorrhoeae infection in England: a modelling study

INTRODUCTION

Diagnoses of gonorrhoea in England rose by 26% between 2018 and 2019. Recent evidence that a vaccine against meningococcal B disease currently offered to infants in the UK (4CMenB) could additionally protect (with 31% efficacy) against gonorrhoea has led to renewed hope for a vaccine. A Phase 2 proof-of-concept trial of 4CMenB vaccination against gonorrhoea in adults is currently underway.

OBJECTIVES

To investigate the potential public health impact of adolescent gonorrhoea vaccination in England, considering different implementation strategies.

METHODS

We developed a deterministic transmission-dynamic model of gonorrhoea infection among heterosexual 13-64-year-olds stratified by age, sex and sexual activity. We explored the impact of a National Immunisation Programme (NIP) among 14-year-olds for a vaccine with 31% efficacy, 6 years' duration of protection, and 85% uptake. We also explored how impact might change for varying efficacy (20-50%) and uptake (75-95%), the addition of a catch-up programme, the use of boosters, and varying duration of protection.

RESULTS

An NIP against gonorrhoea could lead to 50,000 (95% credible interval, CrI 31,000-80,000) and 849,000 (95%CrI 476,000-1,568,000) gonorrhoea infections being averted over 10 and 70 years, respectively, in England, for a vaccine with 31% efficacy and 85% uptake. This is equivalent to 25% (95%CrI 17-33%) of heterosexual infections being averted over 70 years. Vaccine impact is predicted to increase over time and be greatest among 13-18-year-olds (39% of infections 95%CrI 31-49% averted) over 70 years. Varying vaccine efficacy and duration of protection had a noticeable effect on impact. Catch-up and booster vaccination increased the short- and long-term impact, respectively.

CONCLUSIONS

A partially-effective vaccine against gonorrhoea infection, delivered to 14-year-olds alongside the MenACWY vaccine, could have an important population impact on gonorrhoea. Catch-up and booster vaccination could be considered alongside cohort vaccination to increase impact.

National and regional differences in meningococcal vaccine recommendations for individuals at an increased risk of meningococcal disease

INTRODUCTION

Invasive meningococcal disease (IMD) is a severe, life-threatening condition caused by infection with Neisseria meningitidis. Currently available vaccines offer protection against the five most common meningococcal disease-causing serogroups and include monovalent and quadrivalent conjugate vaccines (MenA, MenC, MenACWY vaccines) and outer membrane vesicle- and/or recombinant protein-based vaccines (MenB vaccines).

AREAS COVERED

Country and regional immunization programs target populations susceptible to IMD and typically emphasize the highest-risk age groups (i.e., infants, adolescents/young adults, and the elderly); however, additional groups are also considered at an elevated risk and are the focus of the current review. Specific increased-risk groups include individuals with underlying immunocompromising medical conditions, university/college students, Indigenous people, laboratory workers, military personnel, men who have sex with men, and travelers to areas with hyperendemic IMD. This review compares established meningococcal vaccination recommendations for these vulnerable groups in Europe, the United States, Australia, New Zealand, Israel, Brazil, and Turkey.

EXPERT OPINION

Recommendations should be standardized to cover all groups at increased risk of IMD.

The Optimal Management of Neisseria gonorrhoeae Infections

Neisseria gonorrhoeae is one of the most frequent etiologic agents of STDs (sexually transmitted diseases). Untreated asymptomatic gonococcal infection in women can lead to spreading of the infection in the sexually active population and could lead to late consequences, such as sterility or ectopic pregnancies. One important issue about N. gonorrhoeae is its increasing resistance to antibiotics. This paper summarized the newest molecular antimicrobial resistance (AMR) detection assays for Neisseria gonorrhoeae connected with the latest therapeutic antimicrobials and gonococcal vaccine candidates. The assays used to detect AMR varied from the classical minimal inhibitory concentration (MIC) detection to whole-genome sequencing. New drugs against multi drug resistant (MDR) N. gonorrhoeae have been proposed and were evaluated in vivo and in vitro as being efficient in decreasing the N. gonorrhoeae burden. In addition, anti-N. gonorrhoeae vaccine candidates are being researched, which have been assessed by multiple techniques. With the efforts of many researchers who are studying the detection of antimicrobial resistance in this bacterium and identifying new drugs and new vaccine candidates against it, there is hope in reducing the gonorrhea burden worldwide.

Insight into Prevention of Neisseria Gonorrhoeae: A Short Review

Neisseria gonorrhoeae (gonococcus) and Neisseria meningitidis (meningococcus) are important global pathogens which cause the sexually transmitted diseases gonorrhea and meningitis, respectively, as well as sepsis. We prepared a review according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA), with the aims of (a) evaluating the data on the MenB vaccination as protection against sexually transmitted infections by N. gonorrhoeae and (b) to briefly comment on the data of ongoing studies of new vaccines. We evaluated existing evidence on the effect of 4CMenB, a multi-component vaccine, on invasive diseases caused by different meningococcal serogroups and on gonorrhea. Non-B meningococcal serogroups showed that the 4CMenB vaccine could potentially offer some level of protection against non-B meningococcal serogroups and N. gonorrhoeae. The assessment of the potential protection conferred by 4CMenB is further challenged by the fact that further studies are still needed to fully understand natural immune responses against gonococcal infections. A further limitation could be the potential differences between the protection mechanisms against N. gonorrhoeae, which causes local infections, and the protection mechanisms against N. meningitidis, which causes systemic infections.

Public health perspective of a pentavalent meningococcal vaccine combining antigens of MenACWY-CRM and 4CMenB

OBJECTIVES

Invasive meningococcal disease (IMD) is a life-threatening disease that can rapidly progress to death or leave survivors with severe, life-long sequelae. Five meningococcal serogroups (A, B, C, W and Y) account for nearly all IMD. Meningococcal serogroup distribution fluctuates over time across the world and age groups. Here, we consider the potential public health impact of a pentavalent MenABCWY vaccine developed to help further control meningococcal disease and improve immunisation rates.

RESULTS

The GSK MenABCWY vaccine combines the antigenic components of MenACWY-CRM (Menveo®) and 4CMenB (Bexsero®), building on a wide body of clinical experience and real-world evidence. Both approved vaccines have acceptable safety profiles, demonstrate immunogenicity, and are broadly used, including in national immunisation programmes in several countries. Since the advent of quadrivalent vaccines, public health in relation to IMD has improved, with a decline in the overall incidence of IMD and an increase in vaccine coverage.

CONCLUSION

A pentavalent MenABCWY has the potential to provide further public health benefits through practical, broad IMD protection programmes encompassing serogroups A, B, C, W and Y, and is currently in late-stage development.