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Safeguarding patients from emerging infectious diseases demands strategies that prioritise patient well-being and protection. Immunobridging is an established trial methodology which has been increasingly employed to ensure patient protection and provide clinicians with swift access to vaccines. It uses immunological markers to infer the effectiveness of a new drug through a surrogate measure of efficacy. Recently, this method has also been employed to authorise novel drugs, such as COVID-19 vaccines, and this article explores the concepts behind immunobridging trials, their advantages, issues, and significance in the context of COVID-19 and other infectious diseases. Our goal is to improve awareness among clinicians, patient groups, regulators, and health leaders of the opportunities and issues of immunobridging, so that fewer patients are left without protection from infectious diseases, particularly from major pathogens that may emerge. [ABSTRACT FROM AUTHOR]

Safeguarding patients from emerging infectious diseases demands strategies that prioritise patient well-being and protection. Immunobridging is an established trial methodology which has been increasingly employed to ensure patient protection and provide clinicians with swift access to vaccines. It uses immunological markers to infer the effectiveness of a new drug through a surrogate measure of efficacy. Recently, this method has also been employed to authorise novel drugs, such as COVID-19 vaccines, and this article explores the concepts behind immunobridging trials, their advantages, issues, and significance in the context of COVID-19 and other infectious diseases. Our goal is to improve awareness among clinicians, patient groups, regulators, and health leaders of the opportunities and issues of immunobridging, so that fewer patients are left without protection from infectious diseases, particularly from major pathogens that may emerge.

• Innovax bivalent HPV vaccine (Cecolin), and Gardasil have similar safety profiles. • Two Cecolin doses six months apart are immunologically non-inferior to Gardasil. • Six months after one dose, Cecolin is highly immunogenic. • Cecolin expands the options for HPV vaccination in low- and middle-income countries. World Health Organization human papillomavirus (HPV) vaccination recommendations include a single- or two-dose schedule in individuals 9–20 years old and advice for generating data on single-dose efficacy or immunobridging. The ongoing Phase 3 trial of Innovax's bivalent (types 16 and 18) HPV vaccine (Cecolin®) assesses in low- and middle-income countries alternative dosing schedules and generates data following one dose in girls 9–14 years old. Interim data for the 6-month dosing groups are presented. In Bangladesh and Ghana, 1,025 girls were randomized to receive either two doses of Cecolin at 6-, 12-, or 24-month intervals; one dose of Gardasil® followed by one dose of Cecolin at month 24; or two doses of Gardasil 6 months apart (referent). Serology was measured by enzyme-linked immunosorbent assay (ELISA) and, in a subset, by neutralization assays. Primary objectives include immunological non-inferiority of the Cecolin schedules to referent one month after the second dose. Safety endpoints include reactogenicity and unsolicited adverse events for 7 and 30 days post-vaccination, respectively, as well as serious adverse events throughout the study. Interim analyses included data from the two groups on a 0, 6-month schedule with 205 participants per group. One month after Dose 2, 100% of participants were seropositive by ELISA and had seroconverted for both antigens. Non-inferiority of Cecolin to Gardasil was demonstrated. Six months following one dose, over 96% of participants were seropositive by ELISA for both HPV antigens, with a trend for higher geometric mean concentration following Cecolin administration. Reactogenicity and safety were comparable between both vaccines. Cecolin in a 0, 6-month schedule elicits robust immunogenicity. Non-inferiority to Gardasil was demonstrated one month after a 0, 6-month schedule. Immunogenicity following one dose was comparable to Gardasil up to six months. Both vaccines were safe and well tolerated (ClinicalTrials.gov No. 04508309). [ABSTRACT FROM AUTHOR]

In a long-term immunogenicity study (1100 days post vaccination) in local Thai dogs the immune response of the oral rabies vaccine SPBN GASGAS was compared to those elicited by a commercial inactivated vaccine using immunobridging. Based on the detection of rabies virus binding (rVBA) and rabies virus neutralizing antibodies (rVNA) as measured by ELISA and Rapid Fluorescent Focus Inhibition Test (RFFIT) the long-term immune response in dogs vaccinated orally with the SPBNA GASGAS strain of rabies vaccine in a bait was non-inferior to a conventional inactivated rabies vaccine. The outcome of this study supports extending the originally claimed duration of immunity (DOI) of SPBN GASGAS after oral vaccination for dogs from 6 to 30 months.

The 12th HPV Prevention and Control meeting was held on June 2–3, 2022, in Antwerp, Belgium. This technical meeting focused on several topics. This report summarises the discussions and lessons learned on two topics: an update on one-dose HPV vaccination studies and humoral immune responses upon HPV vaccination. Long-term follow-up studies from Costa Rica (eleven years) and India (ten years) report stable levels of antibodies after a single HPV vaccination. High vaccine effectiveness against incident persistent HPV 16/18 infection was seen in India (95.4%, 85.0–99.9) ten years postvaccination and in Kenya (97.5%, 81.7–99.7) eighteen months postvaccination, an important observation in a setting with a higher HPV prevalence. The potential impact of HPV vaccination using a one-dose schedule in India was modelled and showed that implementation of one-dose schedule can contribute towards achieving WHO Cervical Cancer elimination goals. These data support the WHO SAGE recommendations for adopting a one-dose schedule for females aged 9–20 years. Immunobridging studies were discussed during the meeting. General agreement was reached that when thoughtfully applied, they can support and accelerate the expanded use of HPV vaccine with new vaccine schedules, age cohorts, or vaccine formulations. Internationally standardised measurements of HPV immune responses important for the progress of HPV vaccinology field. Humoral immune responses upon HPV vaccination plateau at 24 months regardless of number of doses, therefore, data should be analysed after at least 24 months of follow-up to bridge studies accurately.

Zaire ebolavirus (EBOV), Sudan ebolavirus (SUDV) and Marburg virus (MARV), are members of the Filoviridae family that can cause severe disease and death in humans and animals. The reemergence of Ebola, Sudan and Marburg virus disease highlight the need for continued availability of safe and effectives vaccines as well as development of new vaccines. While randomized controlled trials using disease endpoints provide the most robust assessment of vaccine effectiveness, challenges to this approach include the unpredictable size, location, occurrence and duration of filovirus disease outbreaks. Thus, other approaches to demonstrating vaccine effectiveness have been considered. These approaches are discussed using examples of preventive vaccines against other infectious diseases. In addition, this article proposes a clinical immunobridging strategy using licensed EBOV vaccines as comparators for demonstrating the effectiveness of filovirus vaccine candidates that are based on the same licensed vaccine platform technology. [ABSTRACT FROM AUTHOR]

The FDA Animal Rule was devised to facilitate approval of candidate vaccines and therapeutics using animal survival data when human efficacy studies are not practical or ethical. This regulatory pathway is critical for candidates against pathogens with high case fatality rates that prohibit human challenge trials, as well as candidates with low and sporadic incidences of outbreaks that make human field trials difficult. Important components of a vaccine development plan for Animal Rule licensure are the identification of an immune correlate of protection and immunobridging to humans. The relationship of vaccine-induced immune responses to survival after vaccination and challenge must be established in validated animal models and then used to infer predictive vaccine efficacy in humans via immunobridging. The Sabin Vaccine Institute is pursuing licensure for candidate filovirus vaccines via the Animal Rule and has convened meetings of key opinion leaders and subject matter experts to define fundamental components for vaccine licensure in the absence of human efficacy data. Here, filoviruses are used as examples to review immune correlates of protection and immunobridging. The points presented herein reflect the presentations and discussions during the second meeting held in October 2021 and are intended to address important considerations for developing immunobridging strategies. [ABSTRACT FROM AUTHOR]

• The 9vHPV vaccine is currently approved for use in Chinese women aged 16–26 years. • Immunogenicity was compared: 9–19- and 27–45- vs. 20–26-year-old Chinese females. • Antibody responses were non-inferior in 9–19- and 27–45- vs. 20–26-year-olds. • Data support bridging of efficacy to Chinese females aged 9–19 years and 27–45 years. • The 9vHPV vaccine was generally well tolerated in Chinese females aged 9–45 years. The 9-valent human papillomavirus (9vHPV; HPV6/11/16/18/31/33/45/52/58) vaccine was approved for use in Chinese women aged 16–26 years in 2018. This phase 3, open-label study (NCT03903562) compared 9vHPV vaccine immunogenicity and safety in Chinese females aged 9–19 years and 27–45 years with Chinese females aged 20–26 years; we report results from day 1 through 1 month post-Dose 3. The study will continue through 54 months post-Dose 3 to assess antibody persistence in Chinese girls aged 9–19 years. Participants aged 9–45 years received three doses of the 9vHPV vaccine. Geometric mean titers (GMTs) and seroconversion percentages for anti-HPV6/11/16/18/31/33/45/52/58 antibodies were determined by competitive Luminex immunoassay in serum samples obtained at day 1 and 1 month post-Dose 3. Adverse events (AEs) within 30 days post-vaccination and serious AEs (SAEs) occurring at any time were recorded. In total, 1990 participants (690 aged 9–19 years; 650 aged 20–26 years; 650 aged 27–45 years) were enrolled. At 1 month post-Dose 3, >99% of participants in the per-protocol immunogenicity population seroconverted to each vaccine HPV type. Anti-HPV6/11/16/18/31/33/45/52/58 antibody GMTs in the 9–19-year age group were non-inferior to those in participants aged 20–26 years. Anti-HPV6/11/16/18/31/33/45/52/58 seroconversion percentages in the 27–45-year age group were non-inferior to those in participants aged 20–26 years. Injection-site and systemic AEs were reported by 43.3% and 50.9%, 50.5% and 57.1%, and 43.8% and 43.4% of participants aged 9–19, 20–26, and 27–45 years, respectively. There were no vaccine-related SAEs, discontinuations due to AEs, and deaths. Antibody responses induced by 9vHPV vaccination in Chinese females aged 9–19 years and 27–45 years were non-inferior to those in Chinese females aged 20–26 years. The vaccine was generally well tolerated. ClinicalTrials.gov Identifier: NCT03903562. [ABSTRACT FROM AUTHOR]

Rapid development and deployment of vaccines is crucial to control the continuously evolving COVID-19 pandemic. The placebo-controlled phase 3 efficacy trial is still the standard for authorizing vaccines in the majority of the world. However, due to a lack of eligible participants in parts of the world, this has not always been feasible. Recently, the Taiwan Food and Drug Administration, following the consensus of the International Coalition of Medicines Regulatory Authorities (ICMRA), adopted the use of immunobridging studies as acceptable for authorizing COVID-19 vaccines in lieu of efficacy data. Here, we describe a study in which our candidate vaccine, MVC-COV1901, an adjuvanted protein subunit vaccine, has been granted emergency use authorization (EUA) in Taiwan based on a noninferiority immunobridging study. Immunogenicity results from the per protocol immunogenicity (PPI) subset (n = 903) from the MVC-COV1901 phase 2 trial were compared with results from 200 subjects who had received an adenovirus vector vaccine, AstraZeneca ChAdOx nCOV-19 (AZD1222), in a separate study. The lower bound of the 95% confidence interval (CI) of the geometric mean titer (GMT) ratio comparing MVC-COV1901 to AZD1222 was 3.4. The lower bound of the 95% CI of the sero-response rate was 95.5%. Both the GMT ratio and sero-response rate exceeded the criteria established by the Taiwan regulatory authority, leading to EUA approval of MVC-COV1901 in Taiwan. [ABSTRACT FROM AUTHOR]

Background The recombinant tetravalent live-attenuated dengue vaccine based on the YF 17D vaccine virus backbone (CYD-TDV) demonstrated vaccine efficacy (VE) against symptomatic, virologically confirmed dengue of any serotype from month 13 to month 25 (VCD-DENV-AnyM13→M25) in the CYD14 (2–14-y-olds) and CYD15 (9–16-y-olds) phase 3 trials. Fifty percent plaque reduction neutralization test (PRNT50) titers are a potential surrogate for immunobridging VE to adults. Methods Using PRNT50 calibration datasets, we applied immunobridging approaches using baseline and/or M13 PRNT50 titers to estimate VE against VCD-DENV-AnyM0→M25 and against hospitalized VCD (HVCD)-DENV-AnyM0→M72 in hypothetical 18–45-y-old and 46–50-y-old CYD14 and CYD15 cohorts. Results Baseline and M13 geometric mean PRNT50 titers were greater in 18–45-y-olds and in 46–50-y-olds vs 9–16-y-olds for most comparisons. Estimated VE (95% CIs against VCD-DENV-AnyM0→M25 ranged from 75.3% to 90.9% (52.5% to 100%) for 18–45-y-olds and 74.8% to 92.0% (53.4% to 100%) for 46–50-y-olds. Estimated VE (95% CIs) against HVCD-DENV-AnyM0→M72 ranged from 58.8% to 78.1% (40.9 to 98.9%) for 18–45-y-olds and 57.2% to 78.4% (40.5 to 97.6%) for 46–50-y-olds. Corresponding predictions among baseline-seropositive individuals yielded comparable or higher VE estimates. Conclusions VE M0→M25 against DENV-Any and VE against HVCD-DENV-AnyM0→M72 are both expected to be higher in 18–45 and 46–50-y-olds vs CYD14 and CYD15 9–16-y-olds. [ABSTRACT FROM AUTHOR]

The FDA Animal Rule was devised to facilitate approval of candidate vaccines and therapeutics using animal survival data when human efficacy studies are not practical or ethical. This regulatory pathway is critical for candidates against pathogens with high case fatality rates that prohibit human challenge trials, as well as candidates with low and sporadic incidences of outbreaks that make human field trials difficult. Important components of a vaccine development plan for Animal Rule licensure are the identification of an immune correlate of protection and immunobridging to humans. The relationship of vaccine-induced immune responses to survival after vaccination and challenge must be established in validated animal models and then used to infer predictive vaccine efficacy in humans via immunobridging. The Sabin Vaccine Institute is pursuing licensure for candidate filovirus vaccines via the Animal Rule and has convened meetings of key opinion leaders and subject matter experts to define fundamental components for vaccine licensure in the absence of human efficacy data. Here, filoviruses are used as examples to review immune correlates of protection and immunobridging. The points presented herein reflect the presentations and discussions during the second meeting held in October 2021 and are intended to address important considerations for developing immunobridging strategies.

Rapid development and deployment of vaccines is crucial to control the continuously evolving COVID-19 pandemic. The placebo-controlled phase 3 efficacy trial is still the standard for authorizing vaccines in the majority of the world. However, due to a lack of eligible participants in parts of the world, this has not always been feasible. Recently, the Taiwan Food and Drug Administration, following the consensus of the International Coalition of Medicines Regulatory Authorities (ICMRA), adopted the use of immunobridging studies as acceptable for authorizing COVID-19 vaccines in lieu of efficacy data. Here, we describe a study in which our candidate vaccine, MVC-COV1901, an adjuvanted protein subunit vaccine, has been granted emergency use authorization (EUA) in Taiwan based on a noninferiority immunobridging study. Immunogenicity results from the per protocol immunogenicity (PPI) subset (n = 903) from the MVC-COV1901 phase 2 trial were compared with results from 200 subjects who had received an adenovirus vector vaccine, AstraZeneca ChAdOx nCOV-19 (AZD1222), in a separate study. The lower bound of the 95% confidence interval (CI) of the geometric mean titer (GMT) ratio comparing MVC-COV1901 to AZD1222 was 3.4. The lower bound of the 95% CI of the sero-response rate was 95.5%. Both the GMT ratio and sero-response rate exceeded the criteria established by the Taiwan regulatory authority, leading to EUA approval of MVC-COV1901 in Taiwan.

• We assessed qHPV vaccine immunogenicity/safety in Chinese females aged 9–26 years (83/85). • The qHPV vaccine elicited robust anti-HPV6/11/16/18 responses in Chinese females (82/85). • Non-inferior immunogenicity was observed in younger versus older Chinese females (82/85). • The qHPV vaccine was generally well tolerated in Chinese females aged 9–26 years (82/85). The quadrivalent human papillomavirus (qHPV; HPV6/11/16/18) vaccine was approved for use in Chinese women aged 20–45 years in 2017. This Phase 3, open-label study (NCT03493542) aimed to assess immunogenicity and safety of the qHPV vaccine in Chinese girls aged 9–19 years versus Chinese young women aged 20–26 years; we report results from Day 1 through Month 7. The study will continue through Month 60 to assess antibody persistence in Chinese girls aged 9–19 years. Participants aged 9–26 years received three doses of the qHPV vaccine (Day 1, Month 2, Month 6). Geometric mean titers (GMTs) and seroconversion percentages for anti-HPV6/11/16/18 antibodies were determined by competitive Luminex immunoassay (cLIA) in serum samples obtained on Day 1 and at Month 7. Injection-site adverse events (AEs) and systemic AEs within 30 days post-vaccination, and serious AEs (SAEs) occurring at any time during the study, were recorded. In total, 766 participants (383 aged 9–19 years; 383 aged 20–26 years) were enrolled and received ≥1 vaccine dose. All participants in the per-protocol immunogenicity population of both age groups seroconverted to each of the vaccine HPV types at Month 7. Anti-HPV6/11/16/18 antibody GMTs at Month 7 in participants aged 9–19 years were non-inferior to those in participants aged 20–26 years. Injection-site AEs and systemic AEs were reported by 36.6% and 49.3% of 9–19-year-olds, and 40.7% and 54.8% of 20–26-year-olds, respectively. There were no vaccine-related SAEs. No participants discontinued the vaccine due to an AE and no deaths were reported. Antibody responses induced by the 3-dose qHPV vaccination regimen in Chinese girls aged 9–19 years were non-inferior to those in Chinese young women aged 20–26 years. The vaccine was generally well tolerated in the study population. ClinicalTrials.gov Identifier: NCT03493542. [ABSTRACT FROM AUTHOR]

A new HPV-16/18 bivalent vaccine expressed by the Escherichia coli has been proven to be efficacious in adult women. A randomized, immunogenicity noninferiority study of this candidate vaccine was conducted in December 2015 in China. Girls aged 9–14 years were randomized to receive 2 doses at months 0 and 6 (n=301) or 3 doses at months 0, 1 and 6 (n=304). Girls aged 15–17 years (n=149) and women aged 18–26 years (n=225) received 3 doses. The objectives included noninferiority analysis of the IgG geometric mean concentration (GMC) ratio (95% CI, lower bound>0.5) to HPV-16 and HPV-18 at month 7 in girls compared with women. In the per-protocol set, the GMC ratio of IgG was noninferior for girls aged 9–17 years receiving 3 doses compared with women (1.76 (95% CI, 1.56, 1.99) for HPV-16 and 1.93 (95% CI, 1.69, 2.21) for HPV-18) and noninferior for girls aged 9–14 years receiving 2 doses compared with women (1.45 (95% CI, 1.25, 1.62) for HPV-16 and 1.17 (95% CI, 1.02, 1.33) for HPV-18). Noninferiority was also demonstrated for neutralizing antibodies. The immunogenicity of the HPV vaccine in girls receiving 3 or 2 doses was noninferior compared with that in young adult women. [ABSTRACT FROM AUTHOR]