Human Vaccines & Immunotherapeutics

There is an urgent need to limit and stop the worldwide coronavirus disease 2019 (COVID-19) pandemic via quick development of efficient and safe vaccination methods. Plasmid DNA vaccines are one of the most remarkable vaccines that can be developed in a short term. pVAX1-SARS-CoV2-co, which is a plasmid DNA vaccine, was designed to express severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike protein. The produced antibodies lead to Immunoreactions against S protein, anti-receptor-binding-domain, and neutralizing action of pVAX1-SARS-CoV2-co, as confirmed in a previous study. To promote the efficacy of the pVAX1-SARS-CoV2-co vaccine, a pyro-drive jet injector (PJI) was employed. PJI is an injection device that can adjust the injection pressure depending on various target tissues. Intradermally-adjusted PJI demonstrated that pVAX1-SARS-CoV2-co vaccine injection caused a strong production of anti-S protein antibodies, triggered immunoreactions and neutralizing actions against SARS-CoV-2. Moreover, a high dose of pVAX1-SARS-CoV2-co intradermal injection via PJI did not cause any serious disorders in the rat model. Finally, virus infection challenge in mice, confirmed that intradermally immunized (via PJI) mice were potently protected from COVID-19 infection. Thus, pVAX1-SARS-CoV2-co intradermal injection via PJI is a safe and promising vaccination method to overcome the COVID-19 pandemic.

We report the development and evaluation of safety and immunogenicity of a whole virion inactivated SARS-COV-2 vaccine (BBV152), adjuvanted with aluminium hydroxide gel (Algel), or a novel TLR7/8 agonist adsorbed Algel. We used a well-characterized SARS-CoV-2 strain and an established vero cell platform to produce large-scale GMP grade highly purified inactivated antigen, BBV152. Product development and manufacturing were carried out in a BSL-3 facility. Immunogenicity was determined at two antigen concentrations (3g and 6g), with two different adjuvants, in mice, rats, and rabbits. Our results show that BBV152 vaccine formulations generated significantly high antigen-binding and neutralizing antibody titers, at both concentrations, in all three species with excellent safety profiles. The inactivated vaccine formulation containing TLR7/8 agonist adjuvant-induced Th1 biased antibody responses with elevated IgG2a/IgG1 ratio and increased levels of SARS-CoV-2 specific IFN-{gamma}+ CD4 T lymphocyte response. Our results support further development for Phase I/II clinical trials in humans.

Recently SARS-CoV-2 Omicron (B.1.1.529) variant was identified in South Africa with numerous mutations in spike protein, and numerous community infections have been reported and raised grave concern around the world. Some studies found that the neutralization effects of several licensed vaccines against Omicron were dramatically reduced, which significantly affected antibody mediated protection, especially for individuals whose immunization were completed after extended period. In this regard, we studied the persistence and neutralization activity toward mutant strains in animal serum immunized with PIKA-adjuvanted recombinant SARS-CoV-2 spike protein subunit vaccine (YS-SC2-010). Here we are reporting that animal serum collected at 596 days after immunization with YS-SC2-010 still retains high and persistent neutralizing activity against all the Variant of Concern (VOC) variants, including Omicron variant. Although it is a blessed event to achieve 20 months long neutralization against Omicron variant after immunization with YS-SC2-010, it was also founded that the neutralization effect of immune serum on Omicron decreased by 6.29 folds as compared to D614G, more significantly when compared with other mutant strains.

We aimed to summarize reliable medical evidence by the meta-analysis of all published clinical trials that investigated the safety, tolerability, and immunogenicity of vaccine candidates against coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The PubMed, Cochrane Library, EMBASE, and medRxiv databases were used to select the studies. 7094 articles were identified initially and 43 were retrieved for more detailed evaluation. 5 randomized, double-blind, placebo-controlled trials were selected. A total of 1604 subjects with either vaccines or placebo infections were included in the meta-analysis within the scope of these articles. According to the results, there is an increase in total adverse events for subjects with either low (95% CI: 1.90-4.29) or high (CI: 2.65-5.63) dose vaccination. The adverse effects of COVID-19 vaccine are mainly local ones including pain, itching, and redness, and no significant difference was identified in the systemic reactions. All adverse effects were transient and resolved within a few days. Moreover, the neutralizing and IgG antibody levels post different dose vaccinations were all significantly increased at day 14/21 (P = 0.0004 and P = 0.0003, respectively) and day 28/35 (P < 0.00001) in vaccine groups compared to placebo controls. Besides, the levels of neutralizing and IgG antibodies were also elevated significantly at from day 14 to 35, versus day 0 (All P < 0.001). In conclusion, our analysis suggests that the current COVID-19 vaccine candidates are safe, tolerated, and immunogenic, which provides important information for further development, evaluation, and clinical application of COVID-19 vaccine.

BackgroundPeople living with chronic disease, particularly seniors older than 60 years old, are lagging behind in the national vaccination campaign in China due to uncertainty of safety and effectiveness. However, this special population made up of most severe symptom and death cases among infected patients and should be prioritized in vaccination program. In this retrospective study, we assessed the safety and immunogenicity of the CoronaVac inactivated vaccines in people with underlying medical conditions to address the vaccine hesitation in this special population. MethodsIn this cohort study, volunteers aged 40 years and older, had received two doses of CoronaVac inactivated vaccines (3-5 weeks interval), been healthy or with at least one of the six diseases: coronary heart disease (CAD), hypertension, diabetes mellitus (DM), chronic respiratory disease (CRD), obesity and cancer, were recruited from 4 study sites in China. The primary safety outcome was the incidence of adverse events within 14 days after each dose of vaccination. The primary immunogenic outcome was geometric mean titer (GMT) of neutralizing antibodies to living SARS-CoV-2 virus at 14-28 days, 3 months, and 6 months after full two-dose vaccination. This study is registered with ChiCTR.org.cn (ChiCTR2200058281) and is active but no longer recruiting. FindingsAmong 1,302 volunteers screened between Jul 5 and Dec 30, 2021, 969 were eligible and enrolled in our cohort, including 740 living with underlying medical conditions and 229 as healthy control. All of them formed the safety cohort. The overall incidence of adverse reactions was 150 (20.27%) of 740 in the comorbidities group versus 32 (13.97%) of 229 in the healthy group, with significant difference (P=0.0334). The difference was mainly contributed by fatigue and injection-site pain in some groups. Most adverse reactions were mild (Grade 1). We did not observe any serious adverse events related to vaccination. By day 14-28 post vaccination, the seroconversion rates and GMT of neutralizing antibody showed no significant difference between disease group and healthy group, except CAD group (P=0.03) and CRD group (P=0.04) showed slight reduction. By day 90, the neutralizing antibody GMTs were significantly reduced in each group, with no significant difference between diseases and healthy group. By day 180, the neutralizing antibody continued to decrease in each group, but with slower declination. InterpretationFor people living with chronic disease especially seniors older than 60 years, the CoronaVac vaccines are as safe as in healthy people. Although the immunogenicity is slightly different in subgroup of some diseases compared with that of the healthy population, the overall trend was consistent. Our findings highlight the evidence to address vaccine hesitancy for seniors and people living with chronic diseases. FundingYunnan Provincial Science and Technology Department (202102AA100051 and 202003AC100010, China), Sinovac Biotech Ltd (PRO-nCOV-4004).

BackgroundThe mRNA vaccine against SARS-CoV-2 has demonstrated remarkable efficacy in protecting against coronavirus disease 2019 (COVID-19), including providing high protection against severe disease during the emergence of variant waves. In this study, we aimed to investigate the safety and immunogenicity of a 2-dose regimen of the LPP-based mRNA vaccine, SW-BIC-213, in Laos. MethodsFor this phase 1/2 clinical trial, we recruited healthy adults aged 18-60 years (phase 1) or [&ge;]18 years (phase 2) from Mahosot Hospital (Vientiane) and Champhone District Hospital (Savannakhet). Participants with SARS-CoV-2 infection, previous COVID-19 vaccination, known allergies to any vaccine component, or pregnancy were excluded. In the phase 1 trial, 41 eligible participants were sequentially assigned to either the 25 g dose group (25 g) or the 45 g dose group (45 g) in accordance with their enrollment order, with 21 participants in 45 g dose group and 20 participants in 25 g dose group. In the phase 2 trial, 480 participants were randomly allocated (2:2:1 ratio) to either the 25 g dose group, 45 g dose group, or placebo group. The primary endpoints for the phase 1 trial were the incidence of local/systemic solicited adverse reactions/events (0-6 days after each vaccination dose), unsolicited adverse events (0-21 days and 0-28 days after the first and second dose of immunization, respectively), and serious adverse events from the first dose of vaccination to 28 days after completing the full course of immunization. In the phase 2 trial, the primary endpoints were the seroconversion rate and geometric mean titer (GMT) of SARS-CoV-2 S-protein specific IgG antibodies and neutralizing antibodies 14 days after the second dose in participants. As for neutralizing antibodies, we detected pseudo-virus neutralizing antibody against wild type (WT), Delta, BA.1 and BA.2. We also detected live viral neutralizing antibody against WT strain 14 days after the second dose. Furthermore, the safety endpoints were also measured during the trial. This seamless phase 1/2 trial was registered with ClinicalTrials.gov under the identifier NCT05144139. ResultsBetween December 3, 2021, and March 31, 2022, a total of 41 participants were recruited in the phase 1 trial, while the phase 2 trial enrolled 480 participants from January 20 to July 6, 2022. In the phase 1 trial, a total of 32 subjects (80.0%) reported 103 cases of adverse reactions. All adverse reactions were limited to Grade 1-2. In the phase 2 trial, a total of 479 subjects, 372 subjects (77.7%) reported 929 cases of adverse reactions. All adverse reactions in severity of Grade 3 were manifested as fever (3.4%, 2.1% and 2.9% in 45 g dose, 25 g dose and placebo group respectively, only observed in adults), except which all other reactions were limited to Grade 1-2. All adverse reactions noted during the study were tolerable, predominantly transient, and resolved spontaneously. No serious adverse events (SAEs) related to vaccination were observed. In Phase 2 study, SW-BIC-213 could elicit a high level of seroconversion rate of pseudo-virus neutralizing antibody against WT (100.0% in 25 g dose group, 99.3% in 45 g dose group), Delta (99.2% in 25 g dose group, 98.0% in 45 g dose group), Omicron BA.1 (84.1% in 25 g dose group, 84.7% in 45 g dose group) and Omicron BA.2 (96.0% in 25 g dose group, 88.8% in 45 g dose group) at 14 days after the second dose. The pseudo-virus neutralizing antibody titer against WT, Delta, BA.1 and BA.2 was all significant higher (P<0.0001) in both 45 g dose group (1175.02, 620.62, 72.39 and 172.80) and 25 g dose group (885.80, 579.40, 47.24 and 101.96) compared with the placebo group (9.67, 10.66, 13.99 and 29.53) at 14 days after the second dose. As for live viral neutralizing antibodies against WT strain, the seroconversion rate could reach more than 94% at 14 days after second dose. The neutralizing antibody titer against WT strain was significantly higher (P<0.0001) in both 45 g dose group (315.00) and 25 g dose group (323.18) compared with the placebo group (8.51) at 14 days after second dose. ConclusionCOVID-19 mRNA vaccine SW-BIC-213 manifests a favorable safety profile and is highly immunogenic in eligible subjects aged [&ge;]18 years.

BackgroundThe safety and immunogenicity of heterologous prime-boost COVID-19 vaccine regimens with one shot of a recombinant adenovirus type-5-vectored COVID-19 vaccine Convidecia has not been reported. MethodsWe conducted a randomized, controlled, observer-blinded trial of heterologous prime-boost immunization with CoronaVac and Convidecia in healthy adults 18-59 years of age. Eligible participants who were primed with one or two doses of CoronaVac were randomly assigned at a 1:1 ratio to receive a booster dose of Convidecia or CoronaVac. Participants were masked to the vaccine received but not to the three-dose or two-dose regimen. The occurrences of adverse reactions within 28 days after the vaccination were documented. The geometric mean titers of neutralizing antibodies against live SARS-CoV-2 virus were measured at 14 and 28 days after the booster vaccination. ResultsBetween May 25 and 26, 2021, a total of 300 participants were enrolled. Participants who received a booster shot with a heterologous dose of Convidecia reported increased frequencies of solicited injection-site reactions than did those received a homogeneous dose of CoronaVac, but frequencies of systemic reactions. The adverse reactions were generally mild to moderate. The heterologous immunization with Convidecia induced higher live viral neutralizing antibodies than did the homogeneous immunization with CoronaVac (197.4[167.7, 232.4] vs. 33.6[28.3, 39.8] and 54.4[37. 9, 78.0] vs. 12.8[9.3, 17.5]) at day 14 in the three- and two-dose regimen cohort, respectively. ConclusionsThe heterologous prime-boost regimen with Convidecia after the priming with CoronaVac was safe and significantly immunogenic than a homogeneous boost with CoronaVac (ClinicalTrials.gov, number NCT04892459).

BackgroundIn the prolonged COVID-19 pandemic, there remains a high need for the development of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine that can be used more safely and effectively to prevents the disease onset or severe disease. To satisfy such unmet need, we are currently developing the inactivated whole particle SARS-CoV-2 vaccine (KD-414) and conducted a phase 2/3 study in healthy adults in Japan to accumulate more immunogenicity and safety data of KD-414 using the dose selected based on the results of the phase 1/2 study. MethodsIn an open-label uncontrolled phase 2/3 study, adults aged 18 years or older without a history of COVID-19 or COVID-19 vaccination received two intramuscular doses of KD-414 at a 28-day intervals, followed by one intramuscular dose 13 weeks after the second dose as the primary immunization. Safety data were collected after the first dose of KD-414 in all participants to evaluate the safety profile. In predetermined immunogenicity analysis subjects, the neutralizing antibody titers against the pseudovirus SARS-CoV-2 (Wuhan) before the first vaccination and after each vaccination with KD-414 were evaluated. ResultsA total of 2500 adults aged 18 years or older were enrolled; 2474 of them received the vaccination up to the second dose, and 2081 completed the third vaccination. Regarding the safety, no deaths or serious adverse reactions were recorded from the first vaccination until 28 days after the third vaccination with KD-414. The incidence of adverse reactions (number of participants with onsets/number of participants in the safety analysis set) was 80.6% (2015/2500). Adverse reactions with an incidence of 10% or more included injection site pain, malaise, headache, injection site erythema, myalgia, and injection site induration. A total of 11 events of grade 3 or higher adverse reactions that prevented daily activities in 9 participants. There was no increasing tendency in the incidence of adverse reactions responding to the vaccinations. To evaluate immunogenicity, 295 first comers enrolled from five age ranges were allocated to the immunogenicity analysis subjects; 291 participants received the vaccination up to the second dose, and 249 participants completed the third vaccination. The geometric mean titers (95% confidence interval [CI]) of neutralizing antibody titers against pseudovirus SARS-CoV-2 (Wuhan) 28 days after the second vaccination and 28 days after the third vaccination with KD-414 were 139.6 (118.9 - 164.0) and 285.6 (244.3 - 334.0), respectively, showing an approximately two-fold increase after the third vaccination compared to that after the second vaccination. The geometric mean titers (95% CI) of neutralizing antibody titers after the third vaccination were 327.6 (269.8 - 397.9), 272.2 (211.5 - 350.4) and 128.0 (51.6 - 317.7) in participants aged 18 to 40 years, 41 to 64 years, and 65 years or older, respectively, showing an age-dependency. ConclusionThis study confirmed the favorable safety profile of KD-414 as a result of three vaccinations of KD-414 administered to over 2000 healthy Japanese participants aged 18 years or older. There were no particular differences in the types and incidences of adverse reactions between vaccinations, and no tendency of an increase in adverse reactions with an increase in the number of vaccinations. Similar to the phase 1/2 study, neutralizing antibody responses appeared to be age-dependent and the highest titers were observed in the age group of 18 - 40 years. A phase 3 study in adults aged 18 - 40 years (jRCT2031210679) and a phase 2/3 study in children aged 6 months - 18 years (jRCT2031220032) are currently ongoing.

BackgroundA major obstacle to successful coronavirus disease (COVID-19) vaccine rollout is vaccine hesitancy. Acceptance of and preferences for COVID-19 vaccination among healthcare workers (HCWs) is critical, because they are a key target group for vaccination programs, and they are also highly influential to vaccine uptake in the wider population. This study sought to comparatively determine the acceptance of and preference for COVID-19 vaccination among HCWs and the general population. MethodsAn Internet-based, region-stratified discrete-choice experiment was conducted among 352 HCWs and 189 general population respondents recruited in March 2020 from 26 Chinese provinces. We accessed knowledge of disease, attitude towards and acceptance of COVID-19 vaccination. Several attributes (related to COVID-19 disease, COVID-19 vaccination and one social acceptance) were identified as key determinants of vaccine acceptance. ResultsHCWs had a more in-depth understanding of COVID-19 and showed a higher willingness to accept COVID-19 vaccines with lower effectiveness and/or more severe adverse effects compared to the general population. 76.4% of HCWs (vs 72.5% of the general population) expressed willingness to receive vaccination ({chi}2=2.904, p=0.234). High levels of willingness to accept influenza (65.3%) and pneumococcal (55.7%) vaccination were also seen in HCWs. Future COVID-19 disease incidence (OR: 4.367, 95% CI 3.721-5.126), decisions about vaccination among social contacts of respondents (OR 0.398, 95% CI 0.339-0.467), and infection risk >30% (OR 2.706, 95% CI 1.776-2.425) significantly increased the probability of vaccination acceptance in HCWs. ConclusionMulti-component interventions to address the key determinants of hesitancy in both HCWs and in the general population should be considered for COVID-19 vaccination programs.

A novel multitope protein-peptide vaccine against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection and disease is described in this report. The initial development and characterization experiments are presented along with proof-of-concept studies for the vaccine candidate UB-612. UB-612 consists of eight components rationally designed for induction of potently neutralizing antibodies and broad T cell responses against SARS-CoV-2: the S1-RBD-sFc fusion protein, six synthetic peptides (one universal peptide and five SARS-CoV-2-derived peptides), a proprietary CpG TLR-9 agonist at low concentration as an excipient, and aluminum phosphate adjuvant. Through immunogenicity studies in Guinea pigs and rats, we optimized the design of protein/peptide immunogens and selected an adjuvant system, yielding a vaccine that provides excellent S1-RBD binding and high neutralizing antibody responses, robust cellular responses, and a Th1-oriented response at low doses. In challenge studies, UB- 612 vaccination reduced viral load and prevented development of disease in mouse and non-human primate challenge models. With a Phase 1 trial completed, a Phase 2 trial ongoing in Taiwan, and additional trials planned to support global authorizations, UB-612 is a highly promising and differentiated vaccine candidate for prevention of SARS-CoV-2 infection and COVID-19 disease. Author SummarySARS-CoV-2 virus, the causative agent of Coronavirus Disease 2019 (COVID-19), has spread globally since its origin in 2019, causing an unprecedented public health crisis that has resulted in greater than 4.7 million deaths worldwide. Many vaccines are under development to limit disease spread and reduce the number of cases, but additional candidates that promote a robust immune response are needed. Here, we describe a multitope protein-peptide vaccine platform that is unique among COVID-19 vaccines. The advantages of our approach are induction of both high levels of neutralizing antibodies as well as a Th/CTL response in the vaccinated host, which mimics the immune response that occurs after natural infection with SARS-CoV-2. We demonstrate that our vaccine is immunogenic and effective in preventing disease in several animal models, including AAV- hACE-2 transduced mice, and both rhesus and cynomolgus macaques. Importantly, no immunopathology was observed in the lungs of immunized animals, therefore showing that antibody-dependent enhancement (ADE) does not occur. Our study provides an additional, novel vaccine candidate for advancement in clinical trials to treat and prevent SARS-CoV-2 infection and COVID-19 disease.

This work was conducted during the COVID-19 pandemic prior to the licensing of any vaccines against COVID-19. Although several COVID-19 vaccines are now commercially available, this research on the development of a combination Severe Acute Respiratory Syndrome-associated Coronavirus (SARS-CoV), SARS-coronavirus 2 (SARS-CoV-2), and Middle Eastern Respiratory Syndrome (MERS) is still relevant and shows how a combination vaccine can be designed, produced and rapidly tested in the laboratory. We present the development of a combination vaccine designed to provide immunity against Severe Acute Respiratory Syndrome-associated Coronavirus (SARS-CoV), SARS-coronavirus 2 (SARS-CoV-2), and Middle Eastern Respiratory Syndrome (MERS). The primary objective of this vaccine design is twofold: to mitigate the burden of coronavirus and to address the specific vulnerability of regions prone to recurrent MERS outbreaks. Our combination vaccine incorporates antigenic components from zoonotic sources, specifically SARS-CoV, SARS-CoV-2, and MERS. We assess the impact of combining different Spike proteins S1 subunit antigens, due to its recognised immunogenic potential, and adjuvants on serum antibody titres, virus neutralizing capabilities, and inter-antigen immune responses. We report a robust and broad antibody response against SARS-CoV-2 and related coronaviruses, which was amplified by different adjuvant formulations, including alum, MPLA, CpG, and Squalene-in-Water Emulsion.

BackgroundIn the current protracted COVID-19 pandemic, SARS-CoV-2 vaccines that have the ability to be used safely and to prevent onset or severe disease are still highly needed. A Phase 1/2 study was conducted in healthy adults and the elderly in Japan to evaluate the immunogenicity, safety, and tolerability of an inactivated whole-virus vaccine (KD-414) that is under development. MethodsIn this double-blind, randomized, placebo-controlled, Phase 1/2 study, adults aged 20 to 64 years and elderly participants aged 65 years or older without a history of COVID-19 were randomly allocated to the following groups: the L group (2.5 g/dose), M group (5 g/dose), or H group (10 g/dose) with KD-414, or the placebo group (2:2:2:1). The participants received KD-414 or the placebo intramuscularly twice at intervals of 28 days. To determine the go-forward dose, safety after the first dosing and neutralizing antibody titers against SARS-CoV-2 at 28 days after the second dosing were evaluated for each group. Additionally, after unblinding, participants in the H group received a third dose of KD-414 (H) approximately 6 months after the second dosing for an exploratory evaluation of the safety and neutralizing antibody titers to be conducted. ResultsA total of 210 participants were enrolled: 105 adults aged 20 to 64 years, and 105 elderly participants aged 65 years or older. Of these participants, 105 adults and 104 elderly participants completed the second dosing, and 28 adults and 31 elderly participants in the H group received a third dose of KD-414 (H). The incidence of adverse reactions from the first dosing to 28 days after the second dosing was 19 of 30 (63.3%), 22 of 31 (71.0%), 22 of 29 (75.9%), and six of 15 (40.0%) for adults, and 14 of 30 (46.7%), 14 of 29 (48.3%), 15 of 31 (48.4%), and six of 15 (40.0%) for elderly participants in the L, M, H, and placebo groups, respectively. No differences in incidence were shown among the KD-414 groups. The most common adverse reaction was injection site pain. Fever that resolved the following day was observed in only 1 adult in the H group after the second dosing; this was a sole Grade 3 or higher adverse reaction. For immunogenicity, the neutralizing antibody seroconversion rate (95% confidence intervals [CI]) against SARS-CoV-2 (vaccine strain) 28 days after the second dosing was 36.7% (19.9-56.1), 38.7% (21.8-57.8), and 72.4% (52.8-87.3) in adults, and 33.3% (17.3-52.8), 31.0% (15.3-50.8), and 45.2% (27.3-64.0) in elderly participants in the L, M, and H groups, respectively, showing a dose response by KD-414. The stratified analysis by age-range for the H group, which observed the highest immunogenicity, also showed an age dependency in the neutralizing antibody responses. Based on these results up to the second dosing, the H (10 g/dose) dosage was determined as the recommended dosage for further clinical development of KD-414. In addition, there was no particular difference between the incidence of adverse reactions after the third dosing and that after the second dosing with KD-414 (H) in participants. Moreover, the geometric mean neutralizing antibody titers (GMTs) against SARS-CoV-2 (vaccine strain) 28 days after the third dosing were 2-fold higher than those at 28 days after the second dosing, and the GMTs 13 weeks after the third dosing were 3-fold higher than those at 13 weeks after the second dosing. The stratified analysis by age-range of Pseudovirus SARS-CoV-2 (D614) spike protein neutralizing antibody titers showed 100.0% neutralizing antibody seroconversion rate and high neutralizing antibody titers in participants aged [&le;] 40 years. ConclusionKD-414 was well tolerated in healthy adults and the elderly at all doses evaluated. In view of the dose-response and age-dependency of the immunogenicity of KD-414 (H) (10 g/dose), it is expected to induce high neutralizing antibody titers, particularly in the age range of 20 to 40 years. A Phase 2/3 study (Japan Registry of Clinical Trials [jRCT] 2071210081), a Phase 3 study (jRCT 2031210679), and a Phase 2/3 study in pediatric participants aged 6 months to 17 years (jRCT 2031220032) using KD-414 (H) are ongoing.

Several factors can potentially influence an individuals vaccination readiness. To facilitate cross-study comparisons, it is essential that researchers use a shared framework to measure these factors. This would not only help determine their relative importance cross different contexts but also would aid in tailoring interventions to enhance vaccine uptake. Historically, five psychological antecedents of vaccination were identified: confidence, complacency, constraints, calculation, and collective responsibility. This 5C scale was later expanded to a 7C model by incorporating two additional components: compliance and conspiracy. Building upon this framework, we propose an eighth component, certification, defined as the persons self-report that, in the past, they have had to provide evidence of vaccination. This component addresses a significant gap in the 7C model, as some individuals reported taking the COVID-19 vaccine primarily to obtain proof of vaccination, a motivation not captured by the 7C model. Our confirmatory factor analysis (N = 406) of a bifactor model of US citizens self-reported COVID-19 vaccination status showed that this eighth component had good psychometric properties and the 8C model had slightly higher criterion validity than the 7C model. We present the 8C model as a framework that provides a richer and more complete descriptions of the factors that determine vaccination readiness and encourage future studies of vaccination readiness to utilise it.

BackgroundBased on placebo data, it has been recently demonstrated that the frequencies of most common adverse events (AEs) of COVID-19 vaccination are overestimated due to negative expectation bias of vaccine recipients (nocebo effect). Since booster studies lack comparators, estimating the extent of the nocebo effect is difficult. We aimed to overcome this obstacle through a systematic comparison of most common AE frequencies across vaccine doses (first, second, booster), age groups, and vaccine vs. placebo arms. MethodsWe systematically assessed systemic AEs in approved COVID-19 vaccines according to the PRISMA guidelines. All documents regarding COVID-19 vaccines with a booster dose authorized by the FDA (cutoff date 19 November 2021) were systematically searched on PubMed and the FDA website. Solicited systemic AEs from all documents supporting approval/authorization were collected. After standardization of doses and age groups, AE frequencies were compared between vaccine and placebo. FindingsTwo trials were identified for BNT162b2 (n=21,785 participants), two for mRNA-1273 (n=22,324), and one for Ad26.COV2.S (n=4,085). Fever cases dropped to about half with the booster dose in all vaccines, whereas all other systemic AE frequencies were similar to the preceding dose. Almost no fever cases occurred with placebo (first/second dose); all other systemic AEs occurred at high frequencies. After subtracting placebo arm values from vaccine values, the frequencies for the various AEs were roughly comparable within each dose for each vaccine. InterpretationFever is the only solicited systemic AE that can be assessed objectively. It occurs about 50% less often with the booster than with the preceding dose. This may indirectly indicate a considerable overestimation of systemic AEs in the case of booster vaccinations and a pronounced nocebo effect. The nocebo effect appears to substantially contribute to the differences in the frequencies of the various systemic AEs. FundingNo funding received. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSA high nocebo effect has recently been shown for the most common solicited adverse events (AEs) based on the randomized controlled trials of several vaccines approved for COVID-19. To date, there has been no systematic review of systemic AEs in COVID-19 vaccines with a booster dose approved by the FDA. Normally, assessing the extent of the nocebo effect requires the implementation of randomized, placebo-controlled studies. However, for ethical reasons, studies underlying the authorization of COVID-19 booster vaccines are not controlled. Therefore, reported AEs lack any reference parameter. We searched PubMed and medRxiv for nocebo effects regarding the objectively measurable AE fever using the terms "(COVID) AND (nocebo) AND (fever)" with no language restrictions; no hits were found on PubMed and six were found on medRxiv. The search without any indication, using only the search terms "(nocebo) AND (fever)", resulted in two hits on PubMed and six hits on medRxiv. An additional search was performed for "(vaccine or COVID) AND nocebo"; 21 hits were found on PubMed and 12 on medRxiv. None of the hits obtained with the three searches showed evidence of relevance for the present topic of a direct association of fever with the nocebo effect. Added value of this studyInstead of placebo AE data as reference parameter, we suggest fever as an objectively measurable value to estimate the extent of the nocebo effect in uncontrolled vaccination studies. To our knowledge, this is a new concept with which evidence for the extent of a possible nocebo effect in COVID-19 booster vaccination can be provided. With this approach we directly supplement information on the most recently reported nocebo effects in first, second and booster vaccine doses. To the best of our knowledge, this is the first study to indirectly compare the solicited systemic AE frequencies of approved COVID-19 vaccines across all doses, with easy-to-understand graphs and based on all approval-relevant trials. This is astonishing, as in the context of a pandemic it is essential to communicate scientific data in a generally understandable manner and according to the highest scientific standards. The graphs provided in this work could serve as an example for such clear communication. Implications of all the available evidenceUsing the example of systemic AEs, we were able to show that the frequency of AEs in COVID-19 booster vaccination may be overestimated. Fever as an objective measure to estimate the nocebo effect could help to optimize public awareness campaigns in the future. The graphic presentation of results facilitates a deeper understanding of complex scientific data and provides new insights. It is therefore ideal for a highly dynamic scientific field and may also be applied to other challenges in the COVID-19 pandemic and beyond.

BackgroundBBIBP-CorV vaccine with two doses and an interval of 3-4 weeks had been proved to have good immunogenicity and efficacy as well as an acceptable safety profile according to our initial research and other similar studies. Maintaining adequate neutralizing antibody levels is also necessary for long-term protection, especially in the midst of the COVID-19 pandemic. Our aim was to evaluate the immune persistence of neutralizing antibody elicited by BBIBP-CorV vaccines with day 0-14, 0-21 and 0-28 schedule, and assess the immunogenicity and safety of a homologous booster dose in the high-risk occupational population aged 18-59 years. MethodsA total of 809 eligible participants, aged 18-59 years, were recruited and randomly allocated to receive BBIBP-CorV vaccine with day 0-14, 0-21 or 0-28 schedule respectively between January and May 2021 in Taiyuan City, Shanxi Province, China among the public security officers and the airport ground staff in initial study. In this secondary study, the responders (GMT [&ge;] 16) at day 28 after priming two-dose vaccine were followed up at months 3, 6 and 10 to evaluate the immune persistence of three two-dose schedules. At month 10, eligible participants of three two-dose schedules were received a homologous booster dose respectively (hereafter abbreviated as 0-14d-10m group, 0-21d-10m group and 0-28d-10m group), and followed up at day 28 post-booster to assess the safety and immunogenicity of the booster dose. The contents of follow-up included the blood samples, oropharyngeal/nasal swabs, and adverse reactions collection. The main outcomes of the study included geometric mean titers (GMT) of neutralizing antibody to live SARS-CoV-2, the positive rates of different criteria and the constituent ratio of GMT of neutralizing antibodies at different follow-up point. Meanwhile, we explored the kinetics of antibody levels of different vaccination regimens by generalized estimating equations (GEE) and used exponent curve model to predict the duration of maintaining protected antibody after the booster dose. We also determined predictors of maintaining protected antibody level within 10 months after the second dose by Cox proportional hazards regression model and nomogram. The trial was registered with ChiCTR.org.cn (ChiCTR2100041705, ChiCTR2100041706). ResultsThe number of 241, 247 and 256 responders (GMT [&ge;] 16) at day 28 after two-dose BBIBP-CorV vaccine in 0-14d, 0-21d and 0-28d schedule were followed-up at months 3, 6, and 10 for immune persistence evaluation. At month 10, a total of 390 participants were eligible and received a booster dose with 130 participants in the 0-14d-10m, 0-21d-10m and 0-28d-10m group respectively, of whom 74.1% (289/390) were male, with a mean age of 37.1{+/-}10.3 years. The GMT of neutralizing antibody in 0-28d-10m and 0-21d-10m group were significantly higher than 0-14d-10m group at month 3 (GMT: 71.6 & 64.2 vs 46.4, P<0.0001), month 6 (GMT: 47.1 & 42.8 vs 30.5, P < 0.0001) and month 10 (GMT: 32.4 vs 20.3, P < 0.0001; 28.8 vs 20.3, P=0.0004) after the second dose. A sharply decrease by 4.85-fold (GMT: 94.4-20.3), 4.67-fold (GMT: 134.4-28.8) and 4.49-fold (GMT: 145.5-32.4) was observed from day 28 to month 10 after the second dose in 0-14d-10m, 0-21d-10m and 0-28d-10m group, respectively, and they had similar decline kinetics (P=0.67). At 28 days after booster dose, a remarkable rebound in neutralizing antibody (GMT: 246.2, 277.5 and 288.6) were observed in three groups, respectively. Notably, the GMT after booster dose was not affected by priming two-dose schedule. The predictive duration of neutralizing antibody declining to the cutoff level of positive antibody response may be 18.08 months, 18.83 months and 19.08 months after booster dose in three groups, respectively. Long-term immune persistence within 10 months after the second dose was associated with age<40, female, and history of influenza vaccination. All adverse reactions were mild after the booster injection. None of the participants were infected SARS-CoV-2 during the trial period. ConclusionsThe priming two-dose BBIBP-CorV vaccine with 0-28 days and 0-21 days schedule could lead a longer persistence of neutralizing antibody than 0-14 days schedule. Maintaining long-term immune persistence was also associated with age<40, female, and history of influenza vaccination. Regardless of priming two-doses vaccination regimens, a homologous booster dose led to a strong rebound in neutralizing antibody and might elicit satisfactory persistent immunity.

Waning vaccine-induced immunity, coupled with the emergence of SARS-CoV-2 variants, has inspired the widespread implementation of COVID-19 booster vaccinations. Here, we evaluated the potentials of the GX-19N DNA vaccine as a heterologous booster to enhance the protective immune response to SARS-CoV-2 in mice primed with either an inactivated virus particle (VP) or mRNA vaccine. We found that in the VP-primed condition, GX-19N enhanced the response of both vaccine-specific antibodies and cross-reactive T-cells to the SARS-CoV-2 variant of concern (VOC) compared to the homologous VP vaccine prime-boost. Under the mRNA-primed condition, GX-19N induced higher vaccine-induced T-cell responses but lower antibody responses than the homologous mRNA vaccine prime-boost. Furthermore, heterologous GX-19N boost induced higher S-specific polyfunctional CD4+ and CD8+ T cell responses than the homologous VP or mRNA prime-boost vaccinations. Our results provide new insights into booster vaccination strategies for the management of novel COVID-19 variants.

In response to the COVID-19 pandemic, an unprecedented level of vaccine development has occurred. As a result, various COVID-19 vaccines have been approved for use. Among these, inactivated virus particle (VP) vaccines have been widely used worldwide, but additional vaccination strategies are needed because of the short duration of immune responses elicited by these vaccines. Here, we evaluated homologous and heterologous prime-boost regimens using a VP vaccine and GX-19N DNA vaccine for their ability to enhance the protective immune response against SARS-CoV-2. We demonstrated that a heterologous prime-boost regimen with the VP vaccine and GX-19N DNA vaccine resulted in enhanced SRBD- & N-specific antibody responses, compared to the homologous VP vaccine prime-boost vaccination. In addition, the neutralizing antibody response was significantly improved with the heterologous VP prime-DNA boost regimen, and the neutralizing antibody induced with the heterologous prime-boost regimen did not decrease against the SARS-CoV-2 variant of concern (VOC). The heterologous VP prime-DNA boost regimen not only significantly increased S- and N-specific IFN-{gamma} T-cell responses, but also induced an equivalent level of T-cell response against SARS-CoV-2 VOCs. Our results provide new insights into prophylactic vaccination strategies for COVID-19 vaccination.

BackgroundThe ReCOV is a recombinant trimeric two-component SARS-CoV-2 subunit vaccine adjuvanted with BFA03. We report the preliminary safety and immunogenicity results for the ReCOV. MethodsThis first in human, randomized, double-blind, placebo-controlled phase I study, was conducted at 2 study sites in New Zealand. Subjects were stratified into two age cohorts (18-55 years and 56-80 years old) and then randomly assigned in a 4:1 ratio to receive two 0.5 mL intramuscular doses of the ReCOV vaccine (20{micro}g or 40{micro}g, adjuvanted with BFA03 in each) or placebo, 21 days apart. The primary endpoints were incidence of solicited local and systemic adverse events (AEs) and unsolicited AEs after each dose; incidence of serious adverse events (SAEs) up to 30 days after the second dose; changes in clinical laboratory tests from baseline up to 7 days after each dose; and changes in vital signs from baseline up to 30 days after the second dose. The key secondary endpoints for immunogenicity were neutralizing antibody titers against SARS-CoV-2, S1 receptor binding domain (RBD) and N-terminal domain (NTD) IgG titers post-vaccination. The T cell-specific immune response elicited by ReCOV were also evaluated. The trial was registered with ClinicalTrials.gov (NCT04818801). FindingsOne hundred participants (50 for each age group) were randomized. The incidence of solicited local AEs in 20g ReCOV, 40g ReCOV, and pooled placebo group among younger adults were 60.0%, 70.0%, and 10.0%, respectively, while among older adults were 55.0%, 84.2%, and 10.0%, respectively. The incidence of solicited systemic AEs in 20g ReCOV, 40g ReCOV, and pooled placebo group among younger adults were 60.0%, 60.0%, and 30.0%, respectively, while among older adults were 50.0%, 52.6%, and 50.0%, respectively. All solicited AEs and unsolicited AEs were mild. No vaccination-related SAE, adverse events of special interest, and AE leading to early discontinuation were reported. ReCOV elicited SARS-CoV-2 neutralizing antibody after the first vaccination, which were increased further after the second vaccination irrespective of dose and age groups. The neutralizing antibody against wild-type SARS-CoV-2 peaked at 14 days post the second vaccination in both 20{micro}g and 40{micro}g ReCOV groups, with GMT of 1643.17 IU/mL and 1289.21 IU/mL among younger adults, and 1122.32 IU/mL and 680.31 IU/mL among older adults, respectively. Similarly, both anti-RBD and anti-NTD specific IgG were elicited after the first vaccination, and peaked at 14 days after the second vaccination. T helper 1 biased cellular responses were observed after ReCOV vaccinations. InterpretationBoth 20 and 40{micro}g ReCOV showed good safety profiles and elicited strong immune responses in the younger and the older adults. The results of this study support the accelerated development of ReCOV. FundingJiangsu Recbio Technology Co., Ltd.

BackgroundThe SARS-CoV-2 virus continues to evolve with recent iterations such as the Omicron sub-variants having potential for increased transmissibility. Of particular interest, the XBB.1.5 variant has been shown to cause vaccine-breakthrough cases. Biological E (BE) has utilized the same platform it used to develop CORBEVAXTM, an ancestral Wuhan strain COVID-19 RBD subunit vaccine (control vaccine), to now develop an XBB.1.5 RBD subunit vaccine (test vaccine). MethodsTo assess the safety and immunogenicity of BEs new XBB.1.5 subunit vaccine, a prospective, randomized, single-blind Phase III study was conducted in participants aged 5 to 80 years. Participants who had not received any other approved COVID-19 vaccine within the last 6 months prior were enrolled and randomized 2:1 to receive two booster doses of either the test vaccine or the control vaccine. The vaccines were administered on Day 0 and Day 28 with immunogenicity assessments on Day 0, Day 28, and Day 42. Safety assessments included the collection of solicited and unsolicited adverse events (AEs) up until Day 56. The primary objective of the study was to show immunogenic superiority of the test vaccine booster series compared to the control vaccine series. This superiority objective was to be concluded if the lower limit of the two-sided 95% confidence interval of the anti-XBB.1.5.RBD neutralizing antibody (nAb) geometric mean titer (GMT) ratio of test:control was >1.0 on either Day 28 or Day 42. Given the emergence of JN.1 as the SARS-CoV-2 strain during the conduct of this study, Day 42 anti-JN.1 nAb were measured in a post hoc immunogenicity assessment. In addition, anti-XBB.1.5 RBD protein IgG concentration in the sera samples were also measured by ELISA on Day 0, Day 28, and Day 42. FindingsA total of 360 participants were enrolled and randomized across 7 sites in India. The nAb GMT ratio of test:control participants was 2.08 (95% CI 1.64 to 2.63) on Day 28 and 2.91 (95% CI 2.38 to 3.56) on Day 42. The geometric mean fold rise (GMFR) of neutralizing antibodies (nAb) was 7.637 (95% CI 6.090 to 9.578) on Day 28 and 17.02 (95% CI 13.79 to 21.01) on Day 42 in the test booster series arm. The nAb GMFRs in the control booster series arm at the same time points were 3.033 (95% CI 2.340 to 3.932) and 4.824 (95% CI 3.731 to 6.236) respectively. Post hoc analyses revealed an nAb GMT ratio of 1.90 (95% CI 1.56 to 2.31) of test:control against the JN.1 SARS-CoV-2 strain. The safety profile of the new XBB.1.5 RBD subunit vaccine was found to be very similar to that of the Ancestral strain vaccine with 59 AEs (about 1 AE for every 8 doses administered) and 27 AEs (a little less than 1 AE for every 8 doses administered) respectively during the study. No serious AEs or AEs of special interest were reported in either the test or control arm of the study. Two cases of pyrexia were medically attended to, one in each arm. InterpretationsBiological Es new XBB.1.5 RBD subunit vaccine was found to be both safe and robustly immunogenic when administered as a two-dose booster series in 5 to 80 year olds. In particular, the vaccine induced a significant rise in neutralizing antibodies against the XBB.1.5 strain as well as cross-protective neutralizing antibodies against the JN.1 SARS-CoV-2 strain. These data are in line with studies of other XBB.1.5 monovalent vaccines and support a positive risk-benefit profile. Real world studies may provide additional evidence about the effectiveness of this new updated vaccine. CTRI Trial Registration IdentifierCTRI/2024/01/061423 FundingBiological E Limited. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSThe SARS-CoV-2 virus has been circulating worldwide ever since its emergence in late 2019. Vaccinations have been particularly useful in preventing hospitalizations and deaths even in those that acquire COVID-19. Multiple technology platforms have been utilized to develop vaccines including mRNA and protein subunit platforms. More recently, immune-evasive SARS-CoV-2 strains have emerged fueling the need for variant-directed boosters. Multiple mRNA monovalent boosters and one protein subunit booster targeting the XBB.1.5 strain have been approved by different national regulatory agencies across the world. Added value of this studyIn this study, we tested a new XBB.1.5 RBD subunit vaccine that was developed using an established yeast-expression system. We ran a single-blinded randomized Phase III study to compare two booster doses of this updated vaccine versus two booster doses of the ancestral strain vaccine developed on the same yeast-expression system. We showed that the safety profile of the two vaccines was comparable. The older of these vaccines has now been safely administered to over 40,000,000 people and has been shown to have an acceptable safety profile. Additionally, the XBB.1.5 RBD subunit vaccine was found to be superior to the ancestral strain vaccine in inducing neutralizing antibodies against the XBB.1.5 strain. Importantly, this updated vaccine also induced neutralizing antibodies against the JN.1 strain, which became the most prevalent circulating SARS-CoV-2 strain during and after the conduct of the study. This study demonstrates a favourable risk-benefit profile of the updated monovalent XBB.1.5 RBD subunit vaccine when administered as a booster series across multiple age groups including children as young as 5 years. Implications of all the available evidenceOur study adds to the growing body of evidence suggesting the use of updated monovalent booster vaccines will be useful in curtailing the morbidity and mortality of the SARS-CoV-2 virus. Various real-world studies have demonstrated the effectiveness of such updated vaccines in preventing hospitalizations and deaths. Protein subunit vaccines such as ours have been extensively used over the past many decades and are more likely to be accepted in an environment of growing vaccine-hesitancy. SARS-CoV-2 vaccines developed on newer platforms such as the mRNA platform and the adenoviral vector platform, while faster to market, have been shown to induce rare but serious adverse events such as myocarditis and thrombosis. Protein subunit SARS-CoV-2 vaccines do not seem to produce as many adverse events suggesting a superior safety profile.

BACKGROUNDThe rising breakthrough infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, especially Omicron and its sub-lineages, have raised an urgent need to develop broad-spectrum vaccines against coronavirus disease 2019 (COVID-19). We have developed a mosaic-type recombinant vaccine candidate, named NVSI-06-09, having immune potentials against a broad range of SARS-CoV-2 variants. METHODSAn ongoing randomized, double-blind, controlled phase 2 trial was conducted to evaluate the safety and immunogenicity of NVSI-06-09 as a booster dose in subjects aged 18 years and older from the United Arab Emirates (UAE), who had completed two or three doses of BBIBP-CorV vaccinations at least 6 months prior to the enrollment. The participants were randomly assigned with 1:1 to receive a booster dose of NVSI-06-09 or BBIBP-CorV. The primary outcomes were immunogenicity and safety against SARS-CoV-2 Omicron variant, and the exploratory outcome was cross-immunogenicity against other circulating strains. RESULTSA total of 516 participants received booster vaccination. Interim results showed a similar safety profile between NVSI-06-09 and BBIBP-CorV booster groups, with low incidence of adverse reactions of grade 1 or 2. For immunogenicity, by day 14 after the booster vaccination, the fold rises in neutralizing antibody geometric mean titers (GMTs) from baseline level elicited by NVSI-06-09 were remarkably higher than those by BBIBP-CorV against the prototype strain (19.67 vs 4.47-fold), Omicron BA.1.1 (42.35 vs 3.78-fold), BA.2 (25.09 vs 2.91-fold), BA.4 (22.42 vs 2.69-fold), and BA.5 variants (27.06 vs 4.73-fold). Similarly, the neutralizing GMTs boosted by NVSI-06-09 against Beta and Delta variants were also 6.60-fold and 7.17-fold higher than those boosted by BBIBP-CorV. CONCLUSIONSA booster dose of NVSI-06-09 was well-tolerated and elicited broad-spectrum neutralizing responses against SARS-CoV-2 prototype strain and immune-evasive variants, including Omicron and its sub-lineages. The immunogenicity of NVSI-06-09 as a booster vaccine was superior to that of BBIBP-CorV. (Funded by LIBP and BIBP of Sinopharm; ClinicalTrials.gov number, NCT05293548).