Efficacy of a Dengue Vaccine Candidate (TAK-003) in Healthy Children and Adolescents 2 Years after Vaccination

BACKGROUND

Takeda's dengue vaccine is under evaluation in an ongoing phase 3 efficacy study; we present a 2-year update.

METHODS

Children (20 099, 4-16 years old) were randomized to receive 2 doses of TAK-003 or placebo 3 months apart and are under surveillance to detect dengue by serotype-specific RT-PCR.

RESULTS

Cumulative efficacy against dengue approximately 27 months since first dose was 72.7% (95% confidence interval [CI], 67.1%-77.3%), including 67.0% (95% CI, 53.6%-76.5%) in dengue-naive and 89.2% (95% CI, 82.4%-93.3%) against hospitalized dengue. In the second year, decline in efficacy was observed (56.2%; 95% CI, 42.3%-66.8%) with the largest decline in 4-5 year olds (24.5%; 95% CI, -34.2% to 57.5%); efficacy was 60.6% (95% CI, 43.8%-72.4%) in 6-11 year and 71.2% (95% CI, 41.0%-85.9%) in 12-16 year age groups. As TAK-003 efficacy varies by serotype, changes in serotype dominance partially contributed to efficacy differences in year-by-year analysis. No related serious adverse events occurred during the second year.

CONCLUSIONS

TAK-003 demonstrated continued benefit independent of baseline serostatus in reducing dengue with some decline in efficacy during the second year. Three-year data will be important to see if efficacy stabilizes or declines further.Clinical Trials Registration. NCT02747927.Takeda's tetravalent dengue vaccine (TAK-003) continued to demonstrate benefit in reducing dengue independent of baseline serostatus up to 2 years after completing vaccination with some decline in efficacy during the second year in 4-16 year olds in dengue-endemic countries.

A new dengue vaccine (TAK-003) now WHO recommended in endemic areas; what about travellers?

Qdenga (Takeda) is now WHO recommended for residents of highly endemic areas. Travellers from dengue non-endemic countries with previous travel-related dengue (any serotype) will benefit from TAK-003 vaccination to prevent a secondary dengue infection during future dengue risk travel. Dengue-naïve travellers have less potential benefit and use will remain discretionary for now.

Characterization of the Type-Specific and Cross-Reactive B-Cell Responses Elicited by a Live-Attenuated Tetravalent Dengue Vaccine

BACKGROUND

Dengue is caused by 4 antigenically distinct serotypes of dengue virus (DENV1-4). Takeda's live attenuated tetravalent dengue vaccine (TAK-003) candidate is composed of an attenuated DENV2 and chimeric viruses containing prM/E of DENV1, 3 and 4 on the DENV2 backbone. The multicolor FluoroSpot (MCF) assay enables quantitation of serotype-specific and cross-reactive individual memory B cells (MBCs) secreting DENV-specific antibodies in a polyclonal mixture.

METHODS

Using the MCF assay, we determined the type-specific and cross-reactive MBC response in peripheral blood mononuclear cells collected pre- and postvaccination from 7 macaques and 15 randomly selected individuals who received TAK-003 (8 DENV seronegative and 7 DENV seropositive) in a phase 2 clinical trial in Singapore (DEN-205 study).

RESULTS

Preexisting DENV-specific MBC responses were detected only in seropositive vaccine recipients at day 0. Following vaccination, both type-specific and cross-reactive MBCs to all 4 DENV serotypes were observed in all macaques and clinical trial participants. The proportion of type-specific MBCs was higher than cross-reactive MBCs and remained stable between day 30 and 360 post vaccination.

CONCLUSIONS

These results demonstrate that, unlike primary or secondary natural DENV infection, tetravalent vaccination elicits tetravalent type-specific MBCs, and thus all 4 components of TAK-003 contribute to the DENV-specific MBC response following vaccination.

CLINICAL TRIALS REGISTRATION

NCT02425098.

Development of a novel assay to assess the avidity of dengue virus-specific antibodies elicited in response to a tetravalent dengue vaccine

Antibody affinity maturation is a critical step in development of functional antiviral immunity; however, accurate measurement of affinity maturation of polyclonal serum antibody responses to particulate antigens such as virions is challenging. We describe a novel avidity assay employing biolayer interferometry and dengue virus-like particles. After validation using anti-dengue monoclonal antibodies, the assay was used to assess avidity of antibody responses to a tetravalent dengue vaccine candidate (TAK-003) in children, adolescents, and adults during two phase 2 clinical trials conducted in dengue-endemic regions. Vaccination increased avidity index and avidity remained high through 1 year postvaccination. Neutralizing antibody titers and avidity index did not correlate overall; however, a correlation was observed between neutralizing antibody titer and avidity index in those subjects with the highest degree of antibody affinity maturation. Therefore, vaccination with TAK-003 stimulates polyclonal affinity maturation and functional antibody responses, including neutralizing antibodies.

Clinical Safety Experience of TAK-003 for Dengue Fever: A New Tetravalent Live Attenuated Vaccine Candidate

BACKGROUND

An unmet medical need remains for an effective dengue tetravalent vaccine that can be administered irrespective of previous dengue exposure. TAK-003, a dengue tetravalent vaccine, has demonstrated efficacy in an ongoing phase 3 trial in children and adolescents living in dengue-endemic areas, with an acceptable safety profile in both dengue-naive and dengue-exposed individuals.

METHODS

Safety findings are presented herein from an integrated analysis of data for healthy 4-60-year-olds from two phase 2 and three phase 3 double-blind, placebo-controlled clinical trials of TAK-003 (TAK-003, n = 14 627; placebo, n = 7167). Safety evaluation included analyses of postinjection reactogenicity, unsolicited adverse events (AEs), serious AEs (SAEs), and deaths. Subgroup analyses were performed by age group, baseline serostatus, and gender.

RESULTS

The most common local and systemic AEs were injection site pain (43% for TAK-003 and 26% for placebo) and headache (34% and 30%, respectively). Injection site AEs were mostly mild and resolved within 1-3 days. Unsolicited AEs and AEs leading to discontinuation occurred with similar frequency across both groups, while SAEs were fewer for TAK-003 recipients (6% vs 8% for placebo). Four of the 5 vaccine-related SAEs (which included hypersensitivity, dengue fever, and dengue hemorrhagic fever) occurred in the placebo group. No deaths were considered vaccine-related. Subgroup analyses showed no differences in safety by baseline serostatus or by gender, albeit analysis by age indicated greater local reactogenicity rates for adolescents (46% for TAK-003 and 28% for placebo) and adults (56% and 19%, respectively) than for children (37% and 25%, respectively).

CONCLUSIONS

No important safety risks were identified, and TAK-003 was well tolerated irrespective of age, gender, or baseline dengue serostatus in recipients aged 4-60 years.

Specificity and Breadth of the Neutralizing Antibody Response to a Live-Attenuated Tetravalent Dengue Vaccine

BACKGROUND

An effective dengue vaccine should ideally induce broadly neutralizing antibody (nAb) responses against all 4 dengue virus (DENV) serotypes.

METHODS

We characterized the specificity and breadth of the nAb response to TAK-003, a live-attenuated tetravalent dengue vaccine, in serum samples from phase 2 and 3 clinical trials.

RESULTS

Microneutralization tests using postvaccination serum showed comparable neutralization against diverse DENV-1-4 genotypes. Reporter virus particle neutralization assays after depletion of anti-DENV-2 nAbs demonstrated that the nAb response to DENV-1, -3, and -4 comprises both type-specific (TS) and cross-reactive (CR) nAbs.

CONCLUSIONS

Therefore, TAK-003 induces broad tetravalent TS and CR nAb responses.

Estimated Efficacy of TAK-003 Against Asymptomatic Dengue Infection in Children/Adolescents Participating in the DEN-301 Trial in Asia Pacific and Latin America

BACKGROUND

TAK-003 has been shown to be well tolerated and effective against symptomatic dengue disease and hospitalization, irrespective of baseline serostatus. Most infections are asymptomatic/subclinical. This study assessed whether TAK-003 could protect against asymptomatic/subclinical infections by evaluating increased neutrlizing antibody titers (NAb) after natural infection.

METHODS

DEN-301(NCT02747927) is a phase 3 trial among 4- to 16-year-old participants who received 2 doses of TAK-003/placebo 3 months apart. These exploratory analyses used NAb measured during the trial. As no well-accepted definition for asymptomatic infection exists, 3 algorithms were evaluated: (1) 4-fold increase in NAb, (2) 4-fold increase in NAb and a minimum titer of 40, and (3) 4-fold increase in NAb and a minimum titer of 4-fold lower-limit-of-quantification. Months 4-9, 9-15, and 15-27 after first vaccination were analyzed.

RESULTS

NAb from 3765 participants were analyzed. From months 4-9, vaccine efficacy (VE) against asymptomatic infection was 51.1%(30.4 to 65.6), 36.1%(6.7-56.3), and 27.3%(-8.2 to 51.2) for algorithms 1, 2, and 3, respectively. VE in baseline seropositive participants per algorithms 1, 2, and 3 was 54.8%(28.8 to 71.3), 47.9%(16.8 to 67.4), and 44.3%(9.9 to 65.6), respectively, and in baseline seronegative participants was 44.4%(2.1 to 68.4), 4.6%(-85.1 to 50.8), and -29.3%(-172.1 to 38.6), respectively. VE against asymptomatic infection gradually decreased from months 4-9 to 9-15 and months 9-15 to 15-27.

CONCLUSIONS

The variability in VE algorithms indicates challenges in accurately assessing VE against asymptomatic infections. TAK-003 had a modest impact on asymptomatic dengue infections in the first months post-vaccination, mainly in baseline seropositive participants.

A Methodological Approach to Measuring the Impact of TAK-003 for the Prevention of Dengue in Dourados, Brazil: Optimizing Strategies for Public Health

Background/Objectives: Takeda's tetravalent dengue vaccine TAK-003 has been approved by the Brazilian regulatory agency ANVISA for dengue disease prevention in individuals aged 4 to 60 years. Dourados, in the state of Mato Grosso do Sul, became the world's first city to implement a mass vaccination campaign targeting approximately 120,000 individuals. An ongoing collaborative, observational, population-based study using national surveillance and vaccination data was planned to measure the impact of the vaccine on the reduction in dengue incidence. Methods: In this manuscript, the study's methodology, including its programmatic steps and public health relevance, is described. A collaborative assessment with multidisciplinary researchers in Brazil was conducted to identify key programmatic areas for the successful implementation of the study. These areas included feasibility and site selection assessment, methodology selection, vaccination program implementation, and public health importance. Results/Conclusions: Identification of the public health problem and understanding the disease burden, local healthcare infrastructure, and strategic partnerships were critical for a robust feasibility assessment. One of the feasibility criteria identified was the ability of the Dourados Municipal Health Secretary and the principal investigator to conduct an active vaccination campaign, utilizing extramural activities and diverse communication channels to increase vaccine acceptance and coverage. The selection of analytical methods, such as time series analysis, was dependent on the national and local structures of the databases and data availability.

[Exanthema after dengue vaccine (TAK003): first data of passive surveillance in a private vaccination center in Argentina]

INTRODUCTION

The tetravalent live virus vaccine developed by Takeda called Qdenga® is available in Argentina and approved for use from 4 years of age without age limit. The objective was to describe clinical characteristics and evolution of the initial reports of rash after the first dose.

MATERIAL AND METHODS

The records of Events Supposedly Attributable to Vaccination or Immunization Reported in a Private Vaccination Center were reviewed between 15/11/2023 and 12/12/2023. Cases with skin rash that occurred outside the application site area were included. The main variables analyzed were age, sex, history of dengue, characteristics of the skin rash, accompanying symptoms, time elapsed from vaccination to the onset of the rash and evolution. The incidence of rash was calculated: cases/10,000 vaccinated.

RESULTS

Out of 12 551 doses applied, 15 cases were included. Median age: 35 years, female sex: 8/15. Clinical forms of presentation: generalized micropapular (3/15), maculopapular (3/15), scarlatiniform (1/15), urticarian (1/15), multiform (1/15), erythematous in the face (1/15) and unspecified (5/15). Most common concomitant symptoms: pruritus (5/15), fever or low-grade fever (6/15), headache (3/15), retro-ocular pain (2/15), asthenia (2/15). Three cases reported a history of dengue. The median number of days of rash presentation was 8 days' postvaccination. All patients progressed favorably. The overall incidence was 1.2/1000 vaccinated.

CONCLUSIONS

In passive surveillance, after more than 12 000 first doses administered, the presence of rash was observed in less than 0.12% of those vaccinated. Everyone evolved favorably.

TAK-003: development of a tetravalent dengue vaccine

INTRODUCTION

Dengue incidence has increased over the past few decades. One tetravalent dengue vaccine based on a yellow fever backbone has been approved, but due to increased risk of severe disease in dengue-naïve recipients, its use is limited to individuals with prior dengue exposure.

AREAS COVERED

We summarize the clinical development of TAK-003, a tetravalent dengue vaccine based on a live-attenuated DENV-2 backbone. We discuss vaccine development and preclinical and clinical work leading to a commercially available formulation. TAK-003 is approved in several countries and the WHO-SAGE recommend TAK-003 to be considered for public programs in high transmission areas for individuals aged 6-16 years. Finally, we discuss the potential role of TAK-003 as part of an integrated multimodal strategy for dengue prevention.

EXPERT OPINION

TAK-003 has been assessed in a comprehensive clinical development program; demonstrating sustained efficacy and safety against all four serotypes in baseline seropositive individuals, and against DENV-1 and DENV-2 in seronegative individuals, and has been well tolerated. Effectiveness in a real world setting and safety will be monitored in ongoing and future studies, particularly for DENV-3 and DENV-4, together with the impact of a booster dose. Overall, TAK-003 shows promise as a new tool for dengue prevention.

Pregnancy outcomes following unintentional exposure to TAK-003, a live-attenuated tetravalent dengue vaccine

BACKGROUND

The tetravalent dengue vaccine TAK-003 is contraindicated during pregnancy. Pregnant women were excluded from TAK-003 clinical studies; however, some pregnancies occurred unintentionally.

RESEARCH DESIGN AND METHODS

This post-hoc analysis of phase 2 and 3 studies, evaluated pregnancy outcomes and neonatal adverse events (AEs) following unintentional vaccination during the time period ('exposure window') when women could be pregnant (within 44 days before last menstrual period until the outcome of pregnancy).

RESULTS

Of the 557 reported pregnancies, 38 (TAK-003, n = 28/375; placebo, n = 10/182) occurred inside the exposure window. Of these, 28 (TAK-003, n = 23; placebo, n = 5) resulted in live births, four resulted in elective terminations (TAK-003, n = 2; placebo, n = 2), five in spontaneous abortions (TAK-003, n = 3; placebo, n = 2) and one unknown outcome (placebo).Of the spontaneous abortions, there was no significant difference between TAK-003 and placebo recipients, or between those occurring within or outside the exposure window. Six participants who received TAK-003 in the exposure window and two neonates experienced serious AEs; none were considered TAK-003 related.

CONCLUSIONS

This post-hoc analysis found no evidence of increased adverse pregnancy outcomes following unintentional TAK-003 vaccination occurring inside the exposure window compared with placebo.

CLINICAL TRIAL REGISTRATION

The clinical trials from which data were extracted are registered at www.clinicaltrials.gov (identifiers are NCT02193087, NCT01511250, NCT02302066, NCT02425098, NCT03746015, NCT02747927, NCT03999996, NCT03423173, NCT03342898, NCT03771963, NCT04313244, NCT02948829, NCT035252119, NCT03341637).

Immunogenicity, Safety and Efficacy of the Dengue Vaccine TAK-003: A Meta-Analysis

The TAK-003 dengue vaccine was licensed in Europe in December 2022, and the official recommendations from most EU countries are still under formulation. To support policymakers, we performed a meta-analysis to quantify TAK-003's immunogenicity, efficacy and safety among seronegative and seropositive populations after the administration of one or two vaccine doses. We included trials retrieved from MEDLINE, Scopus and ClinicalTrials.gov. The outcomes were the rates of seroconversion, virologically confirmed dengue fever and serious adverse events after each vaccine dose. Data were combined using random-effect proportion or head-to-head meta-analyses. We retrieved a total of 19 datasets, including >20,000 participants. TAK-003 showed an excellent safety profile, and the immunogenicity after two doses against the four DENV serotypes was ≥90% among both adults and children/adolescents who were either seronegative or seropositive at baseline. A single dose was able to elicit a high immunogenic response among adults (≥70%) and children/adolescents (≥90%). The primary two-dose immunization course halved the risk of all types of virologically confirmed dengue fever among seropositive children/adolescents, but seronegative minors were only protected against the diseases caused by DENV-1 and DENV-2. Overall, the results support the use of TAK-003 for the prevention of dengue fever in the pediatric population of endemic countries. Uncertainties remain on the use of a single vaccine dose in non-endemic countries.

Early onset of protection of the TAK-003 dengue vaccine: Data from the DEN-301 clinical trial

Exploring time-to-onset of efficacy of the live-attenuated dengue vaccine TAK-003 is important for individuals living in, or traveling to, dengue-endemic areas. This protocol-defined exploratory analysis of the Tetravalent Immunization against Dengue Efficacy Study (TIDES) investigated TAK-003's onset of efficacy after the first and before the second dose, administered 3 months later, in healthy participants aged 4-16 years randomly assigned 2:1 to receive TAK-003 or placebo. The number of virologically confirmed dengue (VCD) cases between first and second vaccinations and the time-to-onset of vaccine efficacy (VE) were assessed in the safety population. Fifty VCD cases occurred between the first and second doses (placebo = 37, TAK-003 = 13). The VE against VCD up to 3 months after the first dose was 82.1 %, with an estimated time-to-onset of ∼14 days. TAK-003 provides rapid onset of protection after the first dose and may be useful in the context of a dengue outbreak or as a travel vaccine.

'Mix and Match' vaccination: Is dengue next?

The severity of the COVID-19 pandemic and the development of multiple SARS-CoV-2 vaccines expedited vaccine 'mix and match' trials in humans and demonstrated the benefits of mixing vaccines that vary in formulation, strength, and immunogenicity. Heterologous sequential vaccination may be an effective approach for protecting against dengue, as this strategy would mimic the natural route to broad dengue protection and may overcome the imbalances in efficacy of the individual leading live attenuated dengue vaccines. Here we review 'mix and match' vaccination trials against SARS-CoV-2, HIV, and dengue virus and discuss the possible advantages and concerns of future heterologous immunization with the leading dengue vaccines. COVID-19 trials suggest that priming with a vaccine that induces strong cellular responses, such as an adenoviral vectored product, followed by heterologous boost may optimize T cell immunity. Moreover, heterologous vaccination may induce superior humoral immunity compared to homologous vaccination when the priming vaccine induces a narrower response than the boost. The HIV trials reported that heterologous vaccination was associated with broadened antigen responses and that the sequence of the vaccines significantly impacts the regimen's immunogenicity and efficacy. In heterologous dengue immunization trials, where at least one dose was with a live attenuated vaccine, all reported equivalent or increased immunogenicity compared to homologous boost, although one study reported increased reactogenicity. The three leading dengue vaccines have been evaluated for safety and efficacy in thousands of study participants but not in combination in heterologous dengue vaccine trials. Various heterologous regimens including different combinations and sequences should be trialed to optimize cellular and humoral immunity and the breadth of the response while limiting reactogenicity. A blossoming field dedicated to more accurate correlates of protection and enhancement will help confirm the safety and efficacy of these strategies.

Neurological Manifestations of Perinatal Dengue

Dengue viruses (DENVs) are single-stranded RNA viruses belonging to the family Flaviviridae. There are four distinct antigenically related serotypes, DENVs types 1, 2, 3, and 4. These are all mosquito-borne human pathogens. Congenital dengue disease occurs when there is mother-to-fetus transmission of the virus and should be suspected in endemic regions in neonates presenting with fever, maculopapular rash, and thrombocytopenia. Although most of the infected infants remain asymptomatic, some can develop clinical manifestations such as sepsis-like illness, gastric bleeding, circulatory failure, and death. Neurological manifestations include intracerebral hemorrhages, neurological malformations, and acute focal/disseminated encephalitis/encephalomyelitis. Dengue NS1Ag, a highly conserved glycoprotein, can help the detection of cases in the viremic stage. We do not have proven specific therapies yet; management is largely supportive and is focused on close monitoring and maintaining adequate intravascular volume.

Unveiling the complexity of vaccine hesitancy: A narrative review focusing on dengue vaccination

Dengue vaccines face significant challenges, including safety concerns, which contribute to vaccine hesitancy. Addressing this complex issue requires targeted strategies to overcome existing barriers. Through an extensive review of current evidence, we identified key factors contributing to vaccine hesitancy and explored strategies to enhance global vaccine uptake. Four conceptual models and five assessment tools were identified to understand and measure vaccine hesitancy. Among the factors, "confidence" emerged as the most influential, followed by "complacency." Vaccine acceptance rates varied widely, ranging from 53% to 95%, depending on the region and population. Key determinants included population characteristics, concerns about efficacy and safety, among others. A comprehensive understanding of these factors is essential to improve vaccine acceptance, support dengue prevention efforts, and ensure public health success.