Protein dose-sparing effect of AS01B adjuvant in a randomized preventive HIV vaccine trial of ALVAC-HIV (vCP2438) and adjuvanted bivalent subtype C gp120.

BACKGROUND: HVTN 120 is a phase 1/2a randomized double-blind placebo-controlled HIV vaccine trial that evaluated the safety and immunogenicity of ALVAC-HIV (vCP2438) and MF59- or AS01B-adjuvanted bivalent subtype C gp120 Env protein at two dose levels in healthy HIV-uninfected adults. Trial registration URL https://clinicaltrials.gov/ct2/show/NCT03122223 and registration number NCT03122223. METHODS: Participants received ALVAC-HIV (vCP2438) alone or placebo at months 0 and 1. At months 3 and 6, participants received either placebo, ALVAC-HIV (vCP2438) with 200µg of bivalent subtype C gp120 adjuvanted with MF59 or AS01B, or ALVAC-HIV (vCP2438) with 40µg of bivalent subtype C gp120 adjuvanted with AS01B. Primary outcomes were safety and immune responses. RESULTS: We enrolled 160 participants, 55% females, 18-40 years old (median age 24 years) of whom 150 received vaccine and 10 placebo. Vaccines were generally safe and well tolerated. At months 6.5 and 12, CD4+ T-cell response rates and magnitudes were higher in the AS01B-adjuvanted groups than in the MF59-adjuvanted group. At month 12, HIV-specific Env-gp120 binding antibody response magnitudes in the 40µg gp120/AS01B group were higher than in either of the 200µg gp120 groups. CONCLUSIONS: The 40µg dose gp120/AS01B regimen elicited the highest CD4+ T-cell and binding antibody responses.

Effect of Dengue Serostatus on Dengue Vaccine Safety and Efficacy.

BACKGROUND: In efficacy trials of a tetravalent dengue vaccine (CYD-TDV), excess hospitalizations for dengue were observed among vaccine recipients 2 to 5 years of age. Precise risk estimates according to observed dengue serostatus could not be ascertained because of the limited numbers of samples collected at baseline. We developed a dengue anti-nonstructural protein 1 (NS1) IgG enzyme-linked immunosorbent assay and used samples from month 13 to infer serostatus for a post hoc analysis of safety and efficacy. METHODS: In a case-cohort study, we reanalyzed data from three efficacy trials. For the principal analyses, we used baseline serostatus determined on the basis of measured (when baseline values were available) or imputed (when baseline values were missing) titers from a 50% plaque-reduction neutralization test (PRNT50), with imputation conducted with the use of covariates that included the month 13 anti-NS1 assay results. The risk of hospitalization for virologically confirmed dengue (VCD), of severe VCD, and of symptomatic VCD according to dengue serostatus was estimated by weighted Cox regression and targeted minimum loss-based estimation. RESULTS: Among dengue-seronegative participants 2 to 16 years of age, the cumulative 5-year incidence of hospitalization for VCD was 3.06% among vaccine recipients and 1.87% among controls, with a hazard ratio (vaccine vs. control) through data cutoff of 1.75 (95% confidence interval [CI], 1.14 to 2.70). Among dengue-seronegative participants 9 to 16 years of age, the cumulative incidence of hospitalization for VCD was 1.57% among vaccine recipients and 1.09% among controls, with a hazard ratio of 1.41 (95% CI, 0.74 to 2.68). Similar trends toward a higher risk among seronegative vaccine recipients than among seronegative controls were also found for severe VCD. Among dengue-seropositive participants 2 to 16 years of age and those 9 to 16 years of age, the cumulative incidence of hospitalization for VCD was 0.75% and 0.38%, respectively, among vaccine recipients and 2.47% and 1.88% among controls, with hazard ratios of 0.32 (95% CI, 0.23 to 0.45) and 0.21 (95% CI, 0.14 to 0.31). The risk of severe VCD was also lower among seropositive vaccine recipients than among seropositive controls. CONCLUSIONS: CYD-TDV protected against severe VCD and hospitalization for VCD for 5 years in persons who had exposure to dengue before vaccination, and there was evidence of a higher risk of these outcomes in vaccinated persons who had not been exposed to dengue. (Funded by Sanofi Pasteur; ClinicalTrials.gov numbers, NCT00842530 , NCT01983553 , NCT01373281 , and NCT01374516 .).

Prevention of M. tuberculosis Infection with H4:IC31 Vaccine or BCG Revaccination.

BACKGROUND: Recent Mycobacterium tuberculosis infection confers a predisposition to the development of tuberculosis disease, the leading killer among global infectious diseases. H4:IC31, a candidate subunit vaccine, has shown protection against tuberculosis disease in preclinical models, and observational studies have indicated that primary bacille Calmette-Guérin (BCG) vaccination may offer partial protection against infection. METHODS: In this phase 2 trial, we randomly assigned 990 adolescents in a high-risk setting who had undergone neonatal BCG vaccination to receive the H4:IC31 vaccine, BCG revaccination, or placebo. All the participants had negative results on testing for M. tuberculosis infection on the QuantiFERON-TB Gold In-tube assay (QFT) and for the human immunodeficiency virus. The primary outcomes were safety and acquisition of M. tuberculosis infection, as defined by initial conversion on QFT that was performed every 6 months during a 2-year period. Secondary outcomes were immunogenicity and sustained QFT conversion to a positive test without reversion to negative status at 3 months and 6 months after conversion. Estimates of vaccine efficacy are based on hazard ratios from Cox regression models and compare each vaccine with placebo. RESULTS: Both the BCG and H4:IC31 vaccines were immunogenic. QFT conversion occurred in 44 of 308 participants (14.3%) in the H4:IC31 group and in 41 of 312 participants (13.1%) in the BCG group, as compared with 49 of 310 participants (15.8%) in the placebo group; the rate of sustained conversion was 8.1% in the H4:IC31 group and 6.7% in the BCG group, as compared with 11.6% in the placebo group. Neither the H4:IC31 vaccine nor the BCG vaccine prevented initial QFT conversion, with efficacy point estimates of 9.4% (P=0.63) and 20.1% (P=0.29), respectively. However, the BCG vaccine reduced the rate of sustained QFT conversion, with an efficacy of 45.4% (P=0.03); the efficacy of the H4:IC31 vaccine was 30.5% (P=0.16). There were no clinically significant between-group differences in the rates of serious adverse events, although mild-to-moderate injection-site reactions were more common with BCG revaccination. CONCLUSIONS: In this trial, the rate of sustained QFT conversion, which may reflect sustained M. tuberculosis infection, was reduced by vaccination in a high-transmission setting. This finding may inform clinical development of new vaccine candidates. (Funded by Aeras and others; C-040-404 ClinicalTrials.gov number, NCT02075203 .).

Efficacy of high-dose versus standard-dose influenza vaccine in older adults.

BACKGROUND: As compared with a standard-dose vaccine, a high-dose, trivalent, inactivated influenza vaccine (IIV3-HD) improves antibody responses to influenza among adults 65 years of age or older. This study evaluated whether IIV3-HD also improves protection against laboratory-confirmed influenza illness. METHODS: We conducted a phase IIIb-IV, multicenter, randomized, double-blind, active-controlled trial to compare IIV3-HD (60 µg of hemagglutinin per strain) with standard-dose trivalent, inactivated influenza vaccine (IIV3-SD [15 µg of hemagglutinin per strain]) in adults 65 years of age or older. Assessments of relative efficacy, effectiveness, safety (serious adverse events), and immunogenicity (hemagglutination-inhibition [HAI] titers) were performed during the 2011-2012 (year 1) and the 2012-2013 (year 2) northern-hemisphere influenza seasons. RESULTS: A total of 31,989 participants were enrolled from 126 research centers in the United States and Canada (15,991 were randomly assigned to receive IIV3-HD, and 15,998 to receive IIV3-SD). In the intention-to-treat analysis, 228 participants in the IIV3-HD group (1.4%) and 301 participants in the IIV3-SD group (1.9%) had laboratory-confirmed influenza caused by any viral type or subtype associated with a protocol-defined influenza-like illness (relative efficacy, 24.2%; 95% confidence interval [CI], 9.7 to 36.5). At least one serious adverse event during the safety surveillance period was reported by 1323 (8.3%) of the participants in the IIV3-HD group, as compared with 1442 (9.0%) of the participants in the IIV3-SD group (relative risk, 0.92; 95% CI, 0.85 to 0.99). After vaccination, HAI titers and seroprotection rates (the percentage of participants with HAI titers ≥ 1:40) were significantly higher in the IIV3-HD group. Conclusions: Among persons 65 years of age or older, IIV3-HD induced significantly higher antibody responses and provided better protection against laboratory-confirmed influenza illness than did IIV3-SD. (Funded by Sanofi Pasteur; ClinicalTrials.gov number, NCT01427309.).

Extended evaluation of the virologic, immunologic, and clinical course of volunteers who acquired HIV-1 infection in a phase III vaccine trial of ALVAC-HIV and AIDSVAX B/E.

BACKGROUND: The Thai Phase III Trial of ALVAC-HIV and AIDSVAX B/E showed an estimated vaccine efficacy (VE) of 31% to prevent acquisition of human immunodeficiency virus (HIV). Here we evaluated the effect of vaccination on disease progression after infection. METHODS: CD4(+) T-cell counts and HIV viral load (VL) were measured serially. The primary analysis evaluated vaccine efficacy (VEP) as the percent reduction (vaccine vs placebo) in cumulative probability of a primary composite endpoint of clinical and CD4(+) count components at prespecified time points after infection. Secondary analyses of biomarker-based endpoints were assessed using marginal mean and linear mixed models. RESULTS: There were 61 endpoints in the modified intent-to-treat cohort (mITT; n = 114). There was no evidence for efficacy at 30, 42, 54, and 60 months in the mITT and per protocol (n = 90) cohorts. Estimated VEP (mITT) was15.8% (-21.9, 41.8) at 60 months postinfection. There was weak evidence of lower VL and higher CD4(+) count at 60 and 66 months in the vaccine group. Lower mucosal VL was observed among vaccine recipients, primarily in semen (P = .04). CONCLUSIONS: Vaccination did not affect the clinical course of HIV disease after infection. A potential vaccine effect on the genital mucosa warrants further study.

Expansion of the HSV-2-specific T cell repertoire in skin after immunotherapeutic HSV-2 vaccine.

The skin at the site of HSV-2 reactivation is enriched for HSV-2-specific T cells. To evaluate whether an immunotherapeutic vaccine could elicit skin-based memory T cells, we studied skin biopsies and HSV-2-reactive CD4+ T cells from PBMCs by T cell receptor (TCR) ß chain (TRB) sequencing before and after vaccination with a replication-incompetent whole-virus HSV-2 vaccine candidate (HSV529). The representation of HSV-2-reactive CD4+ TRB sequences from PBMCs in the skin TRB repertoire increased after the first vaccine dose. We found sustained expansion after vaccination of unique, skin-based T cell clonotypes that were not detected in HSV-2-reactive CD4+ T cells isolated from PBMCs. In one participant, a switch in immunodominance occurred with the emergence of a TCR αß pair after vaccination that was not detected in blood. This TCRαß was shown to be HSV-2 reactive by expression of a synthetic TCR in a Jurkat-based NR4A1 reporter system. The skin in areas of HSV-2 reactivation possessed an oligoclonal TRB repertoire that was distinct from the circulation. Defining the influence of therapeutic vaccination on the HSV-2-specific TRB repertoire requires tissue-based evaluation.

Expansion of the HSV-2-specific T cell repertoire in skin after immunotherapeutic HSV-2 vaccine.

The skin at the site of HSV-2 reactivation is enriched for HSV-2-specific T cells. To evaluate whether an immunotherapeutic vaccine could elicit skin-based memory T cells, we studied skin biopsies and HSV-2-reactive CD4+ T cells from peripheral blood mononuclear cells (PBMCs) by T cell receptor ß (TRB) sequencing before and after vaccination with a replication-incompetent whole virus HSV-2 vaccine candidate (HSV529). The representation of HSV-2-reactive CD4+ TRB sequences from PBMCs in the skin TRB repertoire increased after the first vaccine dose. We found sustained expansion after vaccination of unique, skin-based T-cell clonotypes that were not detected in HSV-2-reactive CD4+ T cells isolated from PBMCs. In one participant a switch in immunodominance occurred with the emergence of a T cell receptor (TCR) αß pair after vaccination that was not detected in blood. This TCRαß was shown to be HSV-2-reactive by expression of a synthetic TCR in a Jurkat-based NR4A1 reporter system. The skin in areas of HSV-2 reactivation possesses an oligoclonal TRB repertoire that is distinct from the circulation. Defining the influence of therapeutic vaccination on the HSV-2-specific TRB repertoire requires tissue-based evaluation.

Innate immune cell activation after HIV-1 vaccine administration is associated with increased antibody production.

The RV144 Thai phase III clinical trial's canarypox-protein HIV vaccine regimen showed modest efficacy in reducing infection. We therefore sought to determine the effects of vaccine administration on innate cell activation and subsequent associations with vaccine-induced immune responses. RV306 was a randomized, double-blind clinical trial in HIV-uninfected Thai adults that tested delayed boosting following the RV144 regimen. PBMC collected from RV306 participants prior to and 3 days after the last boost were used to investigate innate immune cell activation. Our analysis showed an increase in CD38+ mucosal associated invariant T (MAIT) cells, CD38+ invariant natural killer T (iNKT) cells, CD38+ γδ T cells, CD38+, CD69+ and HLA-DR+ NK cells 3 days after vaccine administration. An increase in CD14-CD16+ non-classical monocytes and CD14+CD16+ intermediate monocytes accompanied by a decrease in CD14+CD16- classical monocytes was also associated with vaccine administration. Inclusion of ALVAC-HIV in the boost did not further increase MAIT, iNKT, γδ T, and NK cell activation or increase the proportion of non-classical monocytes. Additionally, NK cell activation 3 days after vaccination was positively associated with antibody titers of HIV Env-specific total IgG and IgG1. Vδ1 T cell activation 3 days after vaccine administration was associated with HIV Env-specific IgG3 titers. Finally, we observed trending associations between MAIT cell activation and Env-specific IgG3 titers and between NK cell activation and TH023 pseudovirus neutralization titers. Our study identifies a potential role for innate cells, specifically NK, MAIT, and γδ T cells, in promoting antibody responses following HIV-1 vaccine administration.

Safety and immunogenicity after a 30-month boost of a subtype C ALVAC-HIV (vCP2438) vaccine prime plus bivalent subtype C gp120/MF59 vaccine boost (HVTN 100): A phase 1-2 randomized double-blind placebo-controlled trial.

Induction of broad, durable immune responses is a challenge in HIV vaccine development. HVTN 100 Part A administered subtype C-containing ALVAC-HIV at months 0 and 1, and ALVAC-HIV with bivalent subtype C gp120/MF59 at months 3, 6 and 12. As IgG binding antibody and T-cell responses were similar or greater at month 12.5 vs. month 6.5, but waned by month 18, we investigated vaccine-elicited immune responses after a month 30 boost in this study, HVTN 100 Part B. From 13 September 2017 to 7 August 2018, a subgroup of vaccinees was randomized to receive intramuscular injections of ALVAC+gp120/MF59 (n = 32) or gp120/MF59 alone (n = 31) and a subgroup of placebo recipients was administered placebo (n = 7) at month 30. Primary outcomes were safety, IgG binding antibodies (bAbs) to vaccine-specific and V1V2 Env proteins and vaccine-specific CD4+ T cells at month 30.5. Secondary outcomes included neutralizing and antibody dependent cellular cytotoxicity functions and durability at months 30 and 36. Both vaccine groups had an acceptable safety profile. There were no statistically significant differences in the occurrence or level of IgG bAbs between the vaccine boost groups for any vaccine-specific or V1V2 antigens. IgG responses were higher to vaccine-matched gp120 than to V1V2. The booster vaccination restored the magnitude-breadth IgG bAb response to V1V2 antigens at month 30.5. However, it rapidly waned by month 36. CD4+ T-cell response rates to the 3 vaccine-matched Env antigens for the combined vaccine groups ranged from 37% at month 30, boosted to as high as 91% at month 30.5, and waned by month 36 to as low as 44%, with no significant differences between the vaccine boost groups. Because these responses waned after 6 months, additional strategies may be needed to maintain the durability of prime-boost vaccine regimens and to generate these or other immune responses that confer protection. Trial registration: South African National Clinical Trials Register (SANCTR number: DOH-27-0215-4796) and ClinicalTrials.gov (NCT02404311).

"Direct and indirect impacts of the COVID-19 pandemic on operational conduct of pediatric vaccine clinical trials".

The coronavirus 2019 (COVID-19) pandemic, as well as the resulting public health measures, impacted many aspects of society. The conduct of important pediatric vaccine trials was among these. Analyzing data from six ongoing non-COVID-19 pediatric vaccine trials we aimed to assess the operational impact of the COVID-19 pandemic using descriptive analyses. We identified multiple operational disruptions in trial conduct. Additionally, we identified higher percentages of missed routine vaccinations than investigational vaccines throughout the observation period. Overall, the impact of the COVID-19 pandemic was most apparent early in the pandemic period while adaptations to the pandemic were developed; however, some disruptions persisted throughout the observation period. Pediatric vaccine clinical trials are critical to developing new and/or improved vaccines for the pediatric population. Continued evaluation of the impacts of COVID-19 on pediatric vaccine clinical trials is warranted.

Additional boosting to the RV144 vaccine regimen increased Fc-mediated effector function magnitude but not durability.

OBJECTIVES: The RV144 vaccine trial resulted in a decreased risk of HIV acquisition that was associated with a nonneutralizing antibody response. The objective of this study was to determine the impact of an additional boost to the RV144 vaccine regimen on antibody effector function and durability. DESIGN: RV306 was a randomized, double-blind late boosting of the RV144 prime-boost regimen in HIV-uninfected Thai adults (NCT01931358). This analysis included study participants who received the RV144 vaccine regimen and received no additional boost (group 1) or were boosted with ALVAC-HIV and AIDSVAX (group 2) or only AIDSVAX alone (group 3) 24 weeks after completing the RV144 series. METHODS: Plasma samples from RV306 study participants were used to measure antibody-dependent cellular phagocytosis (ADCP), antibody-dependent neutrophil phagocytosis (ADNP), antibody-dependent complement deposition (ADCD), antibody-dependent cellular cytotoxicity (ADCC), trogocystosis, and gp120-specifc IgG subclasses. RESULTS: Additional boosting increased the magnitude of all Fc-mediated effector functions 2 weeks following the additional boost compared with 2 weeks after completing the RV144 regimen. However, only trogocytosis remained higher 24-26 weeks after the last vaccination for the study participants receiving an additional boost compared with those that did not receive an additional boost. The additional boost increased IgG1 and IgG4 but decreased IgG3 gp-120 specific antibodies compared with 2 weeks after completing the RV144 regimen. CONCLUSION: Additional boosting of RV144 improved the magnitude but not the durability of some Fc-mediated effector functions that were associated with vaccine efficacy, with trogocytosis being the most durable.

Safety and immunogenicity of a variant-adapted SARS-CoV-2 recombinant protein vaccine with AS03 adjuvant as a booster in adults primed with authorized vaccines: a phase 3, parallel-group study.

Background: In a parallel-group, international, phase 3 study (ClinicalTrials.govNCT04762680), we evaluated prototype (D614) and Beta (B.1.351) variant recombinant spike protein booster vaccines with AS03-adjuvant (CoV2 preS dTM-AS03). Methods: Adults, previously primed with mRNA (BNT162b2, mRNA-1273), adenovirus-vectored (Ad26.CoV2.S, ChAdOx1nCoV-19) or protein (CoV2 preS dTM-AS03 [monovalent D614; MV(D614)]) vaccines were enrolled between 29 July 2021 and 22 February 2022. Participants were stratified by age (18-55 and ≥ 56 years) and received one of the following CoV2 preS dTM-AS03 booster formulations: MV(D614) (n = 1285), MV(B.1.351) (n = 707) or bivalent D614 + B.1.351 (BiV; n = 625). Unvaccinated adults who tested negative on a SARS-CoV-2 rapid diagnostic test (control group, n = 479) received two primary doses, 21 days apart, of MV(D614). Anti-D614G and anti-B.1.351 antibodies were evaluated using validated pseudovirus (lentivirus) neutralization (PsVN) assay 14 days post-booster (day [D]15) in 18-55-year-old BNT162b2-primed participants and compared with those pre-booster (D1) and on D36 in 18-55-year-old controls (primary immunogenicity endpoints). PsVN titers to Omicron BA.1, BA.2 and BA.4/5 subvariants were also evaluated. Safety was evaluated over a 12-month follow-up period. Planned interim analyses are presented up to 14 days post-last vaccination for immunogenicity and over a median duration of 5 months for safety. Findings: All three boosters elicited robust anti-D614G or -B.1.351 PsVN responses for mRNA, adenovirus-vectored and protein vaccine-primed groups. Among BNT162b2-primed adults (18-55 years), geometric means of the individual post-booster versus pre-booster titer ratio (95% confidence interval [CI]) were: for MV (D614), 23.37 (18.58-29.38) (anti-D614G); for MV(B.1.351), 35.41 (26.71-46.95) (anti-B.1.351); and for BiV, 14.39 (11.39-18.28) (anti-D614G) and 34.18 (25.84-45.22 (anti-B.1.351). GMT ratios (98.3% CI) versus post-primary vaccination GMTs in controls, were: for MV(D614) booster, 2.16 (1.69; 2.75) [anti-D614G]; for MV(B.1.351), 1.96 (1.54; 2.50) [anti-B.1.351]; and for BiV, 2.34 (1.84; 2.96) [anti-D614G] and 1.39 (1.09; 1.77) [anti-B.1.351]. All booster formulations elicited cross-neutralizing antibodies against Omicron BA.2 (across priming vaccine subgroups), Omicron BA.1 (BNT162b2-primed participants) and Omicron BA.4/5 (BNT162b2-primed participants and MV D614-primed participants). Similar patterns in antibody responses were observed for participants aged ≥56 years. Reactogenicity tended to be transient and mild-to-moderate severity in all booster groups. No safety concerns were identified. Interpretation: CoV2 preS dTM-AS03 boosters demonstrated acceptable safety and elicited robust neutralizing antibodies against multiple variants, regardless of priming vaccine. Funding: Sanofi and Biomedical Advanced Research and Development Authority (BARDA).

Efficacy of a bivalent (D614 + B.1.351) SARS-CoV-2 Protein Vaccine.

Background: COVID-19 vaccines with alternative strain compositions are needed to provide broad protection against newly emergent SARS-CoV-2 variants of concern. Methods: We conducted a global Phase 3, multi-stage efficacy study (NCT04904549) among adults aged ≥18 years. Participants were randomized 1:1 to receive two intramuscular injections 21 days apart of a bivalent SARS-CoV-2 recombinant protein vaccine with AS03-adjuvant (5 µg of ancestral (D614) and 5 µg of B.1.351 [beta] variant spike protein) or placebo. Symptomatic COVID-19 was defined as laboratory-confirmed COVID-19 with COVID-19-like illness (CLI) symptoms. The primary efficacy endpoint was the prevention of symptomatic COVID-19 ≥14 days after the second injection (post-dose 2 [PD2]). Results: Between 19 Oct 2021 and 15 Feb 2022, 12,924 participants received ≥1 study injection. 75% of participants were SARS-CoV-2 non-naïve. 11,416 participants received both study injections (efficacy-evaluable population [vaccine, n=5,736; placebo, n=5,680]). Up to 15 March 2022, 121 symptomatic COVID-19 cases were reported (32 in the vaccine group and 89 in the placebo group) ≥14 days PD2 with a vaccine efficacy (VE) of 64.7% (95% confidence interval [CI] 46.6; 77.2%). VE was 75.1% (95% CI 56.3; 86.6%) in non-naïve and 30.9% (95% CI -39.3; 66.7%) in naïve participants. Viral genome sequencing identified the infecting strain in 68 cases (Omicron [BA.1 and BA.2 subvariants]: 63; Delta: 4; Omicron and Delta: 1). The vaccine was well-tolerated and had an acceptable safety profile. Conclusions: A bivalent vaccine conferred heterologous protection against symptomatic infection with newly emergent Omicron (BA.1 and BA.2) in non-naïve adults 18-59 years of age.

ALVAC-HIV and AIDSVAX B/E vaccination induce improved immune responses compared with AIDSVAX B/E vaccination alone.

The RV144 phase III vaccine trial demonstrated that ALVAC-HIV and AIDSVAX B/E administration over 6 months resulted in 31% efficacy in preventing HIV acquisition, while administration of AIDSVAX B/E alone in both VAX003 and VAX004 studies failed to show efficacy. In this study, we aimed to understand the impact of ALVAC-HIV on the development of cellular, humoral, and functional immune responses compared to the administration of AIDSVAX B/E alone. ALVAC-HIV in combination with 3 doses of AIDSVAX B/E significantly increased CD4+ HIV-specific T cell responses, polyfunctionality, and proliferation compared with 3 doses of AIDSVAX B/E alone. Additionally, Env-specific plasmablasts and A244-specific memory B cells were identified with a significantly higher magnitude in the group that received ALVAC-HIV. Subsequently, data revealed increased magnitude of plasma IgG binding to and avidity for HIV Env in participants who received ALVAC-HIV compared with 3 doses of AIDSVAX B/E alone. Lastly, levels of the Fc-mediated effector functions antibody-dependent cellular cytotoxicity, NK cell activation, and trogocytosis were significantly increased in participants who received ALVAC-HIV compared with those receiving AIDSVAX B/E alone. Taken together, these results suggest that ALVAC-HIV plays an essential role in developing cellular and humoral immune responses to protein-boosted regimens relative to protein alone.

Efficacy of a bivalent (D614 + B.1.351) SARS-CoV-2 recombinant protein vaccine with AS03 adjuvant in adults: a phase 3, parallel, randomised, modified double-blind, placebo-controlled trial.

BACKGROUND: COVID-19 vaccines with alternative strain compositions are needed to provide broad protection against newly emergent SARS-CoV-2 variants of concern. This study aimed to describe the clinical efficacy and safety of a bivalent SARS-CoV-2 recombinant protein vaccine as a two-injection primary series during a period of circulation of the omicron (B.1.1.529) variant. METHODS: We conducted a phase 3, parallel, randomised, modified double-blind, placebo-controlled trial in adults aged 18 years or older at 54 clinical research centres in eight countries (Colombia, Ghana, India, Kenya, Mexico, Nepal, Uganda, and Ukraine). Participants were recruited from the community and randomly assigned (1:1) by use of an interactive response technology system to receive two intramuscular 0·5 mL injections, 21 days apart, of the bivalent vaccine (5 µg of ancestral [D614] and 5 µg of beta [B.1.351] variant spike protein, with AS03 adjuvant) or placebo (0·9% normal saline). All participants, outcome assessors, and laboratory staff performing assays were masked to group assignments; those involved in the preparation and administration of the vaccines were unmasked. Participants were stratified by age (18-59 years and ≥60 years) and baseline SARS-CoV-2 rapid serodiagnostic test positivity. Symptomatic COVID-19 was defined as laboratory-confirmed (via nucleic acid amplification test or PCR test) COVID-19 with COVID-19-like illness symptoms. The primary efficacy endpoint was the clinical efficacy of the bivalent vaccine for prevention of symptomatic COVID-19 at least 14 days after the second injection (dose 2). Safety was assessed in all participants receiving at least one injection of the study vaccine or placebo. This trial is registered with ClinicalTrials.gov (NCT04904549) and is closed to recruitment. FINDINGS: Between Oct 19, 2021, and Feb 15, 2022, 13 002 participants were enrolled and randomly assigned to receive the first dose of the study vaccine (n=6512) or placebo (n=6490). 12 924 participants (6472 in the vaccine group and 6452 in the placebo group) received at least one study injection, of whom 7542 (58·4%) were male and 9693 (75·0%) were SARS-CoV-2 non-naive. Of these 12 924 participants, 11 543 (89·3%) received both study injections (5788 in the vaccine group and 5755 in the placebo group). The efficacy-evaluable population after dose 2 comprised 11 416 participants (5736 in the vaccine group and 5680 in the placebo group). The median duration of follow-up was 85 days (IQR 50-95) after dose 1 and 58 days (29-70) after dose 2. 121 symptomatic COVID-19 cases were reported at least 14 days after dose 2 (32 in the vaccine group and 89 in the placebo group), with an overall vaccine efficacy of 64·7% (95% CI 46·6 to 77·2). Vaccine efficacy against symptomatic COVID-19 was 75·1% (95% CI 56·3 to 86·6) in SARS-CoV-2 non-naive participants and 30·9% (-39·3 to 66·7) in SARS-CoV-2-naive participants. Viral genome sequencing identified the infecting strain in 68 (56·2%) of 121 cases (omicron [BA.1 and BA.2] in 63; delta in four; and both omicron and delta in one). Immediate unsolicited adverse events were reported by four (<0·1%) participants in the vaccine group and seven (0·1%) participants in the placebo group. Immediate unsolicited adverse reactions within 30 min after any injection were reported by four (<0·1%) participants in the vaccine group and six (<0·1%) participants in the placebo group. In the reactogenicity subset with available data, solicited reactions (solicited injection-site reactions and solicited systemic reactions) within 7 days after any injection occurred in 1398 (57·8%) of 2420 vaccine recipients and 983 (40·9%) of 2403 placebo recipients. Grade 3 solicited reactions were reported by 196 (8·1%; 95% CI 7·0 to 9·3) of 2420 vaccine recipients and 118 (4·9%; 4·1 to 5·9) of 2403 placebo recipients within 7 days after any injection, with comparable frequencies after dose 1 and dose 2 in the vaccine group. At least one serious adverse event occurred in 30 (0·5%) participants in the vaccine group and 26 (0·4%) in the placebo group. The proportion of adverse events of special interest and deaths was less than 0·1% in both study groups. No adverse event of special interest, serious adverse event, or death was deemed to be treatment related. There were no reported cases of thrombosis with thrombocytopenia syndrome, myocarditis, pericarditis, Bell's Palsy, or Guillain-Barré syndrome, or other immune-mediated diseases. INTERPRETATION: The bivalent variant vaccine conferred heterologous protection against symptomatic SARS-CoV-2 infection in the epidemiological context of the circulating contemporary omicron variant. These findings suggest that vaccines developed with an antigen from a non-predominant strain could confer cross-protection against newly emergent SARS-CoV-2 variants, although further investigation is warranted. FUNDING: Sanofi, US Biomedical Advanced Research and Development Authority, and the US National Institute of Allergy and Infectious Diseases.

Efficacy of a monovalent (D614) SARS-CoV-2 recombinant protein vaccine with AS03 adjuvant in adults: a phase 3, multi-country study.

Background: The literature on first generation COVID-19 vaccines show they were less effective against new SARS-CoV-2 variants of concern including Omicron (BA.1, BA.2, BA.4 and BA.5 subvariants). New vaccines developed against variant strains may provide cross-protection against emerging variants when used as boosters and facilitate vaccination across a range of countries, healthcare settings and populations. However, there are no data on such vaccines when used as a primary series. Methods: A global Phase 3, multi-stage efficacy study (NCT04904549) among adults (≥18 years) was conducted in 53 research centres in eight countries (United States, Honduras, Japan, Colombia, Kenya, India, Ghana, Nepal). Participants were randomized 1:1 to receive two intramuscular injections of a monovalent SARS-CoV-2 recombinant protein vaccine with AS03-adjuvant (10 µg of the spike (S) protein from the ancestral D614 strain) or placebo on Day 1 (D01) and Day 22 (D22). The primary efficacy endpoint was prevention of virologically confirmed SARS-CoV-2 infection with symptoms of COVID-19-like illness (CLI) ≥14 days after the second injection (post-dose 2 [PD2]) in participants who were SARS-CoV-2 naïve on D01 + D22. Safety and reactogenicity were also evaluated. Findings: Between May 26 and November 7, 2021, 10,114 participants received ≥1 study injection, and 9441 participants received both injections. 2108 (20.8%) participants were SARS-CoV-2 naïve at D01 and D22. The primary endpoint was analysed in a subset of the full analysis set (the modified full analysis set PD2 [mFAS-PD2], excluding participants who did not complete the vaccination schedule or received vaccination despite meeting one of the contraindication criteria, had onset of symptomatic COVID-19 between the first injection and before 14 days after the second injection, or participants who discontinued before 14 days after the second injection [n = 9377; vaccine, n = 4702; placebo, n = 4675]). Data were available for 2051 SARS-CoV-2 naïve and 7159 non-naïve participants. At the cut-off date (January 28, 2022), symptomatic COVID-19 was reported in 169 naïve participants (vaccine, n = 81; placebo, n = 88) ≥14 days PD2, with a vaccine efficacy (VE) of 15.3% (95% CI, -15.8; 38.2). VE regardless of D01/D22 serostatus was 32.9% (95% CI, 15.3; 47.0) and VE in non-naïve participants was 52.7% (95% CI, 31.2; 67.9). Viral genome sequencing was performed up to the data cut-off point and identified the infecting strain in 99/169 adjudicated cases in the PD2 naïve population (Delta [25], Omicron [72], other variants [3], one participant had infection with both Delta and Omicron variants and has been included in the totals for both Delta and Omicron). The vaccine was well-tolerated with an acceptable safety profile. Interpretation: In the context of changing circulating viral variants, it is challenging to induce protection in naïve individuals with a two-dose priming schedule based on the parental D614 strain. However, while the primary endpoint of this trial was not met, the results show that a monovalent D614 vaccine can still be of value in individuals previously exposed to SARS-CoV-2. Funding: This study was funded in whole or in part by Sanofi and by federal funds from the Biomedical Advanced Research and Development Authority, part of the office of the Administration for Strategic Preparedness and Response at the U.S. Department of Health and Human Services under contract number HHSO100201600005I, and in collaboration with the U.S. Department of Defense Joint Program Executive Office for Chemical, Biological, Radiological, and Nuclear Defense under contract number W15QKN-16-9-1002. The views presented here are those of the authors and do not purport to represent those of the Department of the Army, the Department of Health and Human Services, or the U.S. government.

Vaccination with ALVAC and AIDSVAX to prevent HIV-1 infection in Thailand.

BACKGROUND: The development of a safe and effective vaccine against the human immunodeficiency virus type 1 (HIV-1) is critical to pandemic control. METHODS: In a community-based, randomized, multicenter, double-blind, placebo-controlled efficacy trial, we evaluated four priming injections of a recombinant canarypox vector vaccine (ALVAC-HIV [vCP1521]) plus two booster injections of a recombinant glycoprotein 120 subunit vaccine (AIDSVAX B/E). The vaccine and placebo injections were administered to 16,402 healthy men and women between the ages of 18 and 30 years in Rayong and Chon Buri provinces in Thailand. The volunteers, primarily at heterosexual risk for HIV infection, were monitored for the coprimary end points: HIV-1 infection and early HIV-1 viremia, at the end of the 6-month vaccination series and every 6 months thereafter for 3 years. RESULTS: In the intention-to-treat analysis involving 16,402 subjects, there was a trend toward the prevention of HIV-1 infection among the vaccine recipients, with a vaccine efficacy of 26.4% (95% confidence interval [CI], -4.0 to 47.9; P=0.08). In the per-protocol analysis involving 12,542 subjects, the vaccine efficacy was 26.2% (95% CI, -13.3 to 51.9; P=0.16). In the modified intention-to-treat analysis involving 16,395 subjects (with the exclusion of 7 subjects who were found to have had HIV-1 infection at baseline), the vaccine efficacy was 31.2% (95% CI, 1.1 to 52.1; P=0.04). Vaccination did not affect the degree of viremia or the CD4+ T-cell count in subjects in whom HIV-1 infection was subsequently diagnosed. CONCLUSIONS: This ALVAC-HIV and AIDSVAX B/E vaccine regimen may reduce the risk of HIV infection in a community-based population with largely heterosexual risk. Vaccination did not affect the viral load or CD4+ count in subjects with HIV infection. Although the results show only a modest benefit, they offer insight for future research. (ClinicalTrials.gov number, NCT00223080.)

Associations of human leukocyte antigen with neutralizing antibody titers in a tetravalent dengue vaccine phase 2 efficacy trial in Thailand.

The recombinant, live, attenuated, tetravalent dengue vaccine CYD-TDV has shown efficacy against all four dengue serotypes. In this exploratory study (CYD59, NCT02827162), we evaluated potential associations of host human leukocyte antigen (HLA) alleles with dengue antibody responses, CYD-TDV vaccine efficacy, and virologically-confirmed dengue (VCD) cases. Children 4-11 years old, who previously completed a phase 2b efficacy study of CYD-TDV in a single center in Thailand, were included in the study. Genotyping of HLA class I and II loci was performed by next-generation sequencing from DNA obtained from 335 saliva samples. Dengue neutralizing antibody titers (NAb) were assessed as a correlate of risk and protection. Regression analyses were used to assess associations between HLA alleles and NAb responses, vaccine efficacy, and dengue outcomes. Month 13 NAb log geometric mean titers (GMTs) were associated with decreased risk of VCD. In the vaccine group, HLA-DRB1*11 was significantly associated with higher NAb log GMT levels (beta: 0.76; p = 0.002, q = 0.13). Additionally, in the absence of vaccination, HLA associations were observed between the presence of DPB1*03:01 and increased NAb log GMT levels (beta: 1.24; p = 0.005, q = 0.17), and between DPB1*05:01 and reduced NAb log GMT levels (beta: -1.1; p = 0.001, q = 0.07). This study suggests associations of HLA alleles with NAb titers in the context of dengue outcomes. This study was registered with clinicaltrials.gov: NCT02827162.

Safety and immunogenicity of SARS-CoV-2 recombinant protein vaccine formulations in healthy adults: interim results of a randomised, placebo-controlled, phase 1-2, dose-ranging study.

BACKGROUND: CoV2 preS dTM is a stabilised pre-fusion spike protein vaccine produced in a baculovirus expression system being developed against SARS-CoV-2. We present interim safety and immunogenicity results of the first-in-human study of the CoV2 preS dTM vaccine with two different adjuvant formulations. METHODS: This phase 1-2, randomised, double-blind study is being done in healthy, SARS-CoV-2-seronegative adults in ten clinical research centres in the USA. Participants were stratified by age (18-49 years and ≥50 years) and randomly assigned using an interactive response technology system with block randomisation (blocks of varying size) to receive one dose (on day 1) or two doses (on days 1 and 22) of placebo or candidate vaccine, containing low-dose (effective dose 1·3 µg) or high-dose (2·6 µg) antigen with adjuvant AF03 (Sanofi Pasteur) or AS03 (GlaxoSmithKline) or unadjuvanted high-dose antigen (18-49 years only). Primary endpoints were safety, assessed up to day 43, and immunogenicity, measured as SARS-C0V-2 neutralising antibodies (geometric mean titres), assessed on days 1, 22, and 36 serum samples. Safety was assessed according to treatment received in the safety analysis set, which included all randomly assigned participants who received at least one dose. Neutralising antibody titres were assessed in the per-protocol analysis set for immunogenicity, which included participants who received at least one dose, met all inclusion and exclusion criteria, had no protocol deviation, had negative results in the neutralisation test at baseline, and had at least one valid post-dose serology sample. This planned interim analysis reports data up to 43 days after the first vaccination; participants in the trial will be followed up for 12 months after the last study injection. This trial is registered with ClinicalTrials.gov, NCT04537208, and is ongoing. FINDINGS: Between Sept 3 and Sept 29, 2020, 441 individuals (299 aged 18-49 years and 142 aged ≥50 years) were randomly assigned to one of the 11 treatment groups. The interim safety analyses included 439 (>99%) of 441 randomly assigned participants (299 aged 18-49 years and 140 aged ≥50 years). Neutralising antibody titres were analysed in 326 (74%) of 441 participants (235 [79%] of 299 aged 18-49 years and 91 [64%] of 142 aged ≥50 years). There were no vaccine-related unsolicited immediate adverse events, serious adverse events, medically attended adverse events classified as severe, or adverse events of special interest. Among all study participants, solicited local and systemic reactions of any grade after two vaccine doses were reported in 81% (95% CI 61-93; 21 of 26) of participants in the low-dose plus AF03 group, 93% (84-97; 74 of 80) in the low-dose plus AS03 group, 89% (70-98; 23 of 26) in the high-dose plus AF03 group, 95% (88-99; 81 of 85) in the high-dose plus AS03 group, 29% (10-56; five of 17) in the unadjuvanted high-dose group, and 21% (8-40; six of 29) in the placebo group. A single vaccine dose did not generate neutralising antibody titres above placebo levels in any group at days 22 or 36. Among participants aged 18-49 years, neutralising antibody titres after two vaccine doses were 13·1 (95% CI 6·40-26·9) in the low-dose plus AF03 group, 20·5 (13·1-32·1) in the low-dose plus AS03 group, 43·2 (20·6-90·4) in the high-dose plus AF03 group, 75·1 (50·5-112·0) in the high-dose plus AS03 group, 5·00 (not calculated) in the unadjuvanted high-dose group, and 5·00 (not calculated) in the placebo group. Among participants aged 50 years or older, neutralising antibody titres after two vaccine doses were 8·62 (1·90-39·0) in the low-dose plus AF03 group, 12·9 (7·09-23·4) in the low-dose plus AS03 group, 12·3 (4·35-35·0) in the high-dose plus AF03 group, 52·3 (25·3-108·0) in the high-dose plus AS03 group, and 5·00 (not calculated) in the placebo group. INTERPRETATION: The lower than expected immune responses, especially in the older age groups, and the high reactogenicity after dose two were probably due to higher than anticipated host-cell protein content and lower than planned antigen doses in the formulations tested, which was discovered during characterisation studies on the final bulk drug substance. Further development of the AS03-adjuvanted candidate vaccine will focus on identifying the optimal antigen formulation and dose. FUNDING: Sanofi Pasteur and Biomedical Advanced Research and Development Authority.

Safety, immunogenicity, and efficacy of a Clostridioides difficile toxoid vaccine candidate: a phase 3 multicentre, observer-blind, randomised, controlled trial.

BACKGROUND: In the absence of a licensed vaccine, Clostridioides (formerly Clostridium) difficile infection represents a substantial health burden. The aim of this study was to evaluate the efficacy, immunogenicity, and safety of a toxoid vaccine candidate. METHODS: We did a phase 3 multicentre, observer-blind, randomised, controlled trial at 326 hospitals, clinics, and clinical research centres in 27 countries in the USA, Canada, Latin America, Europe, and the Asia-Pacific region. We included adults aged 50 years or older who were considered to be at an increased risk of C difficile infection because they had previously had two hospital stays (each ≥24 h in duration) and had received systemic antibiotics in the previous 12 months (risk stratum 1), or because they were anticipating being admitted to hospital for 72 h or more for elective surgery within 60 days of enrolment (risk stratum 2). Eligible participants were stratified by geographical region and the two risk strata, and randomly assigned (2:1), with a fixed block size of three, to receive either a C difficile toxoid vaccine candidate, containing toxoids A and B (C difficile vaccine candidate group), or a placebo vaccine (placebo group). Participants, investigators, and personnel responsible for collecting safety data and analysing blood and stool samples were masked to group assignment. Personnel responsible for study product preparation and administration were not masked to group assignment. One dose (0·5 mL) of C difficile vaccine candidate or placebo vaccine was administered intramuscularly on days 0, 7, and 30. The primary outcome was the efficacy of the vaccine in preventing symptomatic C difficile infection, defined as having three or more loose stools in a period of 24 h or less, loose stools for 24 h or more, and a PCR-positive test for C difficile toxin B in a loose stool sample, within 3 years after the final vaccine dose. The primary outcome was measured in the modified intention-to-treat population (ie, all participants who received at least one injection of the assigned vaccine). The safety of the vaccine was assessed in the safety analysis set (ie, all participants who had received at least one injection, analysed according to the product received). This study is registered with WHO/ICTRP, number U111-1127-7162, and ClinicalTrials.gov, number NCT01887912, and has been terminated. FINDINGS: Between July 30, 2013, and Nov 17, 2017, we enrolled and randomly assigned 9302 participants to the C difficile vaccine candidate group (n=6201) or to the placebo group (n=3101). 6173 (99·5%) participants in the C difficile vaccine candidate group and 3085 (99·5%) participants in the placebo group received at least one dose of the vaccine. The study was terminated after the first planned interim analysis because of futility. In the C difficile vaccine candidate group, 34 C difficile infections were reported over 11 697·2 person-years at risk (0·29 infections per 100 person-years [95% CI 0·20-0·41]) compared with 16 C difficile infections over 5789·4 person-years at risk in the placebo group (0·28 infections per 100 person-years [0·16-0·45]), indicating a vaccine efficacy of -5·2% (95% CI -104·1 to 43·5). In the C difficile vaccine candidate group, 2847 (46·6%) of 6113 participants reported an adverse event within 30 days of injection compared with 1282 (41·9%) of 3057 participants in the placebo group. The proportion of participants who had an adverse event leading to study discontinuation was 4·8% in both groups (296 participants in the C difficile vaccine candidate group and 146 participants in the placebo group). 1662 (27·2%) participants in the C difficile vaccine candidate group reported at least one serious adverse event compared with 851 (27·8%) participants in the placebo group. INTERPRETATION: In adults at risk for C difficile infection, a bivalent C difficile toxoid vaccine did not prevent C difficile infection. Since the C difficile vaccine candidate met the criteria for futility, the study was terminated and clinical development of this vaccine candidate was stopped. FUNDING: Sanofi Pasteur.