The efficiency of COVID-19 vaccines among taiwanese patients with varied comorbidities

Background/Aims: The global pandemic of COVID-19 has caused tremendous loss of human life since 2019. Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is one of the best policies to control the pandemic. The vaccination efficacy in Taiwanese patients with different comorbidities is elusive and to be explored. Method(s): Uninfected subjects who received 3-doses of mRNA vaccines (Moderna, BioNTech), non-replicating viral vector-based vaccines (AstraZeneca, AZ) or protein subunit vaccines (Medigen COVID-19 vaccine, MVC) were prospectively enrolled. SARSCoV2- IgG spike antibody level was determined (Abbott [SARS-CoV- 2 IgG II]) within 3 months after the last dose of vaccination. Charlson Comorbidity Index (CCI) was applied to disclose the association of vaccine titer and underlying comorbidities. Result(s): A total of 824 subjects were enrolled in the current study. The mean age was 58.9 years and males accounted for 48.7% of the population. The proportion of CCI with 0-1, 2-3 and>4 was 52.8% (n = 435), 31.3% (n = 258) and 15.9% (n = 131), respectively. The most commonly used vaccination combination was AZ-AZ-Moderna (39.2%), followed by Moderna-Moderna-Moderna (27.8%) and AZAZ- BioNTech (14.7%), respectively. The mean vaccination titer was 3.11 log BAU/mL after a median 48 days of the 3rd dose. Subjects of male gender, lower body mass index, chronic kidney disease, higher CCI, and receiving AZ-AZ based vaccination were likely to have a lower titer of antibody. There was a decreasing trend of antibody titer with the increase of CCT (trend P<0.001). Linear regression analysis revealed that AZ-AZ-based vaccination (beta: 0.341, 95% confidence intervals [CI]: 0.144, 0.21, P<0.001) and higher CCI (beta: - 0.055, CI: - 0.096, - 0.014, P = 0.009) independently correlated with low IgG spike antibody levels. Conclusion(s): Patients with more comorbidities had a poor response to 3 doses of COVID-19 vaccination. Further studies are warranted to clarify the efficacy of booster vaccination in the population. The vaccine titer did not differ between patient with or without chronic liver disease.

Overview on Mrna Vaccines Beyond Covid-19

COVID-19 mRNA vaccines: COVID-19 pandemic has made an extraordinary impact on global vaccine technology platform developments. Never in human history have there at least 6 vaccine platforms including: inactivated, protein subunit, VLP and other 3 new platforms i.e., mRNA, viral vector, and DNA, with more than 160 vaccine candidates being developed and tested in clinical trials. Nonetheless, among these several vaccine platforms, mRNA vaccine has been proven to be one of the most effective vaccines against COVID-19. There are two mRNA vaccines authorized for emergency use within a year and currently more than 20 mRNA vaccines are in clinical trials. The main advantages of mRNA vaccines are that they are speedily to design and develop, induce strong antibody and T-cell responses, manufacturing faster and at a lower cost. However, one of the major limitations is that it must be stored in cold temperatures. Currently more than billion doses of COVID-19 mRNA vaccines have been given globally. mRNA vaccines will be a key platform for next pandemics preparedness, it is therefore establishing this platform in various regions and LMICs is critical. Beyond COVID-19: A number of viral and cancer mRNA vaccines have been developing even before COVID-19. At least 12 mRNA vaccines against various infectious diseases are now in clinical evaluation, including Chikungunya virus, Cytomegalovirus, Epstein-Barr virus, Human metapneumovirus and parainfluenza virus type3, HIV, Influenza, Nipah, Rabies, Lasa, RSV, Zika, Varicella-zoster virus. Only few are entering phase 3 such as a CMV vaccine, RSV, seasonal influenza. Current mRNA cancer vaccines development, including brain, breast, melanoma, esophagus, lung, ovarian, prostate and solid tumors. Most are aimed for personalized therapy. By 2023, at least 1 viral mRNA vaccine may get approval, whereas a cancer vaccine might take much longer time. Nevertheless, the remaining challenge at the global level is how to truly overcome the vaccine inequity issues in a sustainable way.Copyright © 2023

Immunogenicity of Sars-Cov-2 Vaccines by Vaccine Type in Randomised Clinical Trials

Background: Currently five SARS-CoV-2 vaccines are approved in North America (FDA) and Europe (EMA). Across the world other vaccines have been developed but not approved in high-income countries. Of the approved vaccines, 2 are mRNA vaccines, 2 are viral vectored vaccines, and 1 is a protein subunit vaccine. As immunogenicity markers are increasingly being used by regulatory agencies as surrogate markers for vaccine efficacy to inform authorization decisions, this meta-analysis compared the size of immunogenicity responses response elicited by the different COVID-19 vaccine types (mRNA, protein subunit, inactivated virus, viral vectors) and approved and unapproved COVID-19 vaccines. Method(s): Systematic review of trial registers and databases identified RCTs for SARS-CoV-2 vaccines. Risk of bias analysis was conducted using the Cochrane Risk of Bias tool. High risk of bias studies were excluded from analysis. Meta-analysis of seroconversion rates and geometric antibody titers (GMT) for neutralising (NAb) and anti-spike antibodies was conducted, each compared with a placebo using random effects model Cochrane-Mantel Haenszel Tests. Result(s): All studies assessed immunogenicity of COVID-19 vaccines on healthy non-immunocompromised adults between the age of 18 and 59. Statistically significant difference was identified between the different vaccine types for NAb GMT, anti-spike GMT, NAb seroconversion, and anti-spike seroconversion (P< 0.00001 for all). Conversely, no statistical significant difference was identified between approved and unapproved vaccines for NAb seroconversion (P=0.39), Nab GMT (P=0.36), anti-spike seroconversion (P=0.07), and antispike GMT (P=0.54). mRNA vaccines had the best immunogenicity results for NAb seroconversion, GMT, and anti-spike seroconversion. Viral vector vaccines had the lowest results for NAb seroconversion and GMT, while inactivated viruses had the lowest result for anti-spike seroconversion and mRNA vaccines for anti-spike GMT. High heterogeneity was observed across the different studies. Conclusion(s): This metanalysis of 35 randomised trials in 33,813 participants showed approved and unapproved vaccines to be comparable in postvaccination GMT values and seroconversion for both NAb and anti-spike. However, while comparing COVID-19 vaccines by vaccine types, statistically significant differences are observed. Variations in study designs, populations enrolled, and infection prevalence during trial duration could have influenced results.

REAL-WORLD EFFECTIVENESS OF mRNA, SUBUNIT, AND VECTOR-BASED VACCINES AGAINST COVID-19

Background: Limited Covid-19 vaccine effectiveness (VE) studies address the mRNA, adenoviral vector-based, and protein subunit vaccines and their mix and match in real-world settings. BNT162v2 (Pfizer-BioNTech), mRNA- 1273 (Moderna), AZD1222 (AstraZeneca), and locally produced MVC-COV1901 (Medigen) are provided under the National Vaccination Program. Taiwan maintained a low circulation of Covid-19 infection until a major epidemic Omicron BA.2, began in April 2022. The study aimed to estimate the VE against moderate and severe (severity) and fatal diseases (death) associated with SARS-CoV-2 among individuals administered one, two, and three doses of vaccination and categorized by vaccine type combinations in this predominantly infection-naive population. Method(s): The study included CDC's administrative records from National Immunization Information System and National Infectious Disease Reporting System from March 21, 2021, to September 30, 2022. Criteria for Covid-19 severity followed WHO's guidelines, and the committee reviewed the records. The study calculated each individual's last administered date to disease onset (incidence rate (IR) per 100,000 person-days) to explore the incidence rate to compare the presence of risk probabilities. Multiple logistic regression was used for vaccine effectiveness analysis. Result(s): Of 23,933,482 individuals included in the study, and 6,202,496 infections, 30,976 severity, and 10,851 deaths were observed. Compared with three doses administered, three doses of AZD1222 or it as primary series plus mRNA or protein-based vaccines were at higher risk of severity (IR: 0.390-0.762), followed by mRNA-1273 (IR: 0.316-0.471), MVC-COV1901 (IR: 0.044-0.196) and BNT162v2 (IR: 0.061-0.197). As for the death outcome, AZD1222 was at higher fatal risk (IR: 0.127-0.269), followed by mRNA-1273 (IR: 0.086-0.125), MVC-COV1901 (IR: 0.013-0.064) and BNT162v2 (IR: 0.015-0.045). VE against the severity of AZD1222 or it as primary series ranged from 65.9% to 77.7%;mRNA vaccines ranged from 86.4% to 96.1%;and protein-based vaccines ranged from 91.4% to 96.2%. A similar pattern of VE against death ranged from 60.9% to 73.7%, 88.2% to 96.2%, and 90.3% to 95.6%. Conclusion(s): Individuals who received their primary series as AZD1222 might not have adequate protection against Covid-19 severity so encourage those vulnerable groups to receive additional booster doses. The study also indicated that protein subunit vaccines provide similar protection against severity and death as mRNA vaccines. (Table Presented).

SARS-CoV-2 S1 Subunit Booster Vaccination Elicits Robust Humoral Immune Responses in Aged Mice.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has raised concerns about reduced vaccine effectiveness and the increased risk of infection, and while repeated homologous booster shots are recommended for elderly and immunocompromised individuals, they cannot completely protect against breakthrough infections. In our previous study, we assessed the immunogenicity of an adenovirus-based vaccine expressing SARS-CoV-2 S1 (Ad5.S1) in mice, which induced robust humoral and cellular immune responses (E. Kim, F. J. Weisel, S. C. Balmert, M. S. Khan, et al., Eur J Immunol 51:1774-1784, 2021, https://doi.org/10.1002/eji.202149167). In this follow-up study, we found that the mice had high titers of anti-S1 antibodies 1 year after vaccination, and one booster dose of the nonadjuvanted rS1Beta (recombinant S1 protein of SARS-CoV-2 Beta [B.1.351]) subunit vaccine was effective at stimulating strong long-lived S1-specific immune responses and inducing significantly high neutralizing antibodies against Wuhan, Beta, and Delta strains, with 3.6- to 19.5-fold increases. Importantly, the booster dose also elicited cross-reactive antibodies, resulting in angiotensin-converting enzyme 2 (ACE2) binding inhibition against spikes of SARS-CoV-2, including Omicron variants, persisting for >28 weeks after booster vaccination. Interestingly, the levels of neutralizing antibodies were correlated not only with the level of S1 binding IgG but also with ACE2 inhibition. Our findings suggest that the rS1Beta subunit vaccine candidate as a booster has the potential to offer cross-neutralization against broad variants and has important implications for the vaccine control of newly emerging breakthrough SARS-CoV-2 variants in elderly individuals primed with adenovirus-based vaccines like AZD1222 and Ad26.COV2.S. IMPORTANCE Vaccines have significantly reduced the incidences of severe coronavirus disease 2019 (COVID-19) cases and deaths. However, the emergence of SARS-CoV-2 variants has raised concerns about their increased transmissibility and ability to evade neutralizing antibodies, especially among elderly individuals who are at higher risks of mortality and reductions of vaccine effectiveness. To address this, a heterologous booster vaccination strategy has been considered as a solution to protect the elderly population against breakthrough infections caused by emerging variants. This study evaluated the booster effect of an S1 subunit vaccine in aged mice that had been previously primed with adenoviral vaccines, providing valuable preclinical evidence for elderly people vaccinated with the currently approved COVID-19 vaccines. This study confirms the potential for using the S1 subunit vaccine as a booster to enhance cross-neutralizing antibodies against emerging variants of concern.

COVID-19 vaccination side effects and related worsening PD symptoms in Parkinson's disease patients: the online survey

Objective: This study aims to identify the adverse events of COVID-19 vaccine in PD patients including the general and specific PD-related side effects. Background(s): SARS-CoV-2 is one of the most contagious and invasive respiratory viruses emerging in the past 3 years and causing serious, life-threatening diseases and sequelae (long COVID-19 syndrome) [1]. Before the development of COVID-19 vaccine, morbidity and mortality of COVID-19 infection were as high as 1% and increased with age and co-morbidity, especially in more advanced PD. The safety of COVID-19 vaccine was approved in the general population, but no study of side effects in PD. [1] There were only 2 case reports of worsening PD symptoms after the mRNA-1273 vaccine (Spikevax) and BNT162b2 mRNA vaccine (Comirnaty). [2],[3] Methods: The study was conducted between July 2021 - January 2022. The online survey was conducted during COVID - 19 lockdown. 230 PD patients responded to the online survey, and 151 patients were included, 11 patients were excluded due to being unvaccinated. 72 patients were excluded due to incomplete responses. 5 patients were excluded due to multiple entries. Result(s): The most common COVID -19 vaccine in our PD patients was ChAdOx1-S vaccine and inactivated COVID-19 Vaccine (Vero Cell). 21.9% (n=33) of the patients had reported adverse effects of COVID-19 vaccination. The most common side effects are fever (60.6%), and headache (48.5%). These adverse effects occurred mostly on the 1st day after vaccination and rarely persisted for more than 7 days. The most reported were worsening bradykinesia (24.2 %) and insomnia (15.2%). We found no statistically significant difference in side effect and PD-related symptoms between ChAdOx1-S vaccine and inactivated COVID-19 vaccine. Conclusion(s): According to the benefits and risks of COVID-19 vaccines do not appear to be different than in the general population, we recommend the approved COVID-19 vaccination to all PD patients. Some symptoms should be observed in the severe motor fluctuation PD, especially bradykinesia because they might experience more motor fluctuation phenomena. If the symptoms do not disturb the activity of daily living, we can wait and see because most of them can spontaneously improve. Further study with mRNA and protein subunit type of vaccines should be done. (table1)(table2)(table3).

Immunogenicity and safety of Biological E's CORBEVAX™ vaccine compared to COVISHIELD™ (ChAdOx1 nCoV-19) vaccine studied in a phase-3, single blind, multicentre, randomized clinical trial.

Optimum formulation of Biological-E's protein subunit CORBEVAX™ vaccine was selected in phase-1 and -2 studies and found to be safe and immunogenic in healthy adult population. This is a phase-3 prospective, single-blinded, randomized, active controlled study conducted at 18 sites across India in 18-80 year-old subjects. This study has two groups; (i) immunogenicity-group, participants randomized either to CORBEVAX™ (n = 319) or COVISHIELD™ arms (n = 320). (ii) Safety-group containing single CORBEVAX™ arm (n = 1500) and randomization is not applicable. Healthy adults without a history of COVID-19 vaccination or SARS-CoV-2 infection were enrolled into immunogenicity arm and subjects seronegative to SARS-CoV-2 infection were enrolled into the safety arm. The safety profile of CORBEVAX™ vaccine was comparable to the comparator vaccine COVISHIELD™. Majority of reported AEs were mild in nature in both arms. The CORBEVAX™ to COVISHIELD™ GMT-ratios at day-42 time-point were 1·15 and 1·56 and the lower limit of the 95% confidence interval for the GMT-ratios was determined as 1·02 and 1·27 against Ancestral and Delta strains of SARS-COV-2 respectively. Both COVISHIELD™ and CORBEVAX™ vaccines showed comparable seroconversion post-vaccination against anti-RBD-IgG response. The subjects in CORBEVAX™ cohort also exhibited higher interferon-gamma secreting PBMC's post-stimulation with SARS-COV-2 RBD-peptides than subjects in COVISHIELD™ cohort.

Structure-Based Design of Recombinant Spike Subunit Vaccine for Coronavirus Diseases

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARSCoV-2) is still surging across the globe and has affected serious problems for both health and the global economy;therefore, the development of a vaccine with good efficacy becomes a must. To tackle the pandemic, numerous sectors of academia, industry, and the government collaborate to develop and investigate potential vaccine platforms. The recombinant subunit vaccine is one of the safest types of vaccine. However, its development has lagged behind other platforms, owing to the need for greater antigen manufacturability and immunogenicity. In this review, we outline several protein engineering strategies carried out in developing the recombinant COVID-19 vaccine, including the fusion of antigens with Fc fragment of human IgG, carrier proteins, trimerization domains, and stabilizing mutations. A systematic literature review was performed to summarize key takeaways from studies on developing recombinant subunit vaccines of SARS-CoV, MERS-CoV, and SARS-CoV-2, highlighting vaccine design and expression system, antigen structure, and in vivo and in vitro results of each protein engineering strategy. Several protein engineering strategies, particularly S protein and RBD, can improve the antigen's stability, manufacturability, and immunogenicity. Finally, novel protein engineering strategies are expected to be further developed to increase the vaccines' overall manufacturing, and the current recombinant vaccine candidates will be further processed into clinical stages to confirm their efficacy against pathogenic human coronaviruses. © 2023, International Journal on Advanced Science, Engineering and Information Technology. All Rights Reserved.

Effect of adjuvanting RBD-dimer-based subunit COVID-19 vaccines with Sepivac SWE™.

Protein subunit vaccines have been widely used to combat infectious diseases, including the current COVID-19 pandemic. Adjuvants play the key role in shaping the quality and magnitude of the immune response to protein and inactivated vaccines. We previously developed a protein subunit COVID-19 vaccine, termed ZF2001, based on an aluminium hydroxide-adjuvanted tandem-repeat dimeric receptor-binding domain (RBD) of the viral spike (S) protein. Here, we described the use of a squalene-based oil-in-water adjuvant, Sepivac SWE™ (abbreviated to SWE), to further improve the immunogenicity of this RBD-dimer-based subunit vaccines. Compared with ZF2001, SWE adjuvant enhanced the antibody and CD4+ T-cell responses in mice with at least 10 fold of dose sparing compared with ZF2001 adjuvanted with aluminium hydroxide. SWE-adjuvanted vaccine protected mice against SARS-CoV-2 challenge. To ensure adequate protection against the currently circulating Omicron variant, we evaluated this adjuvant in combination with Delta-Omicron chimeric RBD-dimer. SWE significantly increased antibody responses compared with aluminium hydroxide adjuvant and afforded greater neutralization breadth. These data highlight the advantage of emulsion-based adjuvants to elevate the protective immune response of protein subunit COVID-19 vaccines.

Safety and immunogenicity of a recombinant receptor-binding domain-based protein subunit vaccine (Noora vaccine™) against COVID-19 in adults: A randomized, double-blind, placebo-controlled, Phase 1 trial.

The development of a safe and effective vaccine is essential to protect populations against coronavirus disease 2019 (COVID-19). There are several vaccine candidates under investigation with different mechanisms of action. In the present study, we have evaluated the safety and immunogenicity of a recombinant receptor-binding domain (RBD)-based protein subunit vaccine (Noora vaccine) against COVID-19 in adults. This Phase 1 trial is a randomized, double-blind, placebo-controlled study to evaluate the safety and immunogenicity of the recombinant RBD-based protein subunit vaccine (Noora vaccine) against COVID-19 in healthy adults volunteers. Eligible participants were included in this study after evaluating their health status and considering the exclusion criteria. They were then randomized into three groups and received three doses of vaccine (80 µg, 120 µg, and placebo) on Days 0, 21, and 35. Primary outcomes including solicited, unsolicited, and medically attended adverse events were recorded during this study. Secondary outcomes including the humoral and cellular immunity (including anti-RBD IgG antibody and neutralizing antibody) were measured on Days 0, 21, 28, 35, 42, and 49 by using the ELISA kit and the Virus Neutralization Test (VNT) was performed on day 49. Totally 70 cases were included in this Phase 1 trial and 60 of them completed the study. Safety assessments showed no severe adverse events. Local pain at the vaccine injection site occurred in 80% of the vaccinated volunteers. Induration and redness at the injection site were the other adverse reactions of this vaccine. There was no significant difference between the studied groups regarding adverse reactions. Anti-RBD IgG antibody and neutralizing antibody assessment showed significant seroconversion in comparison to the placebo group (80%, and 100% respectively, p < 0.001). The cellular immunity panel also showed mild to moderate induction of TH1 responses and the VNT showed 78% of seroprotection. The results of this Phase 1 trial showed acceptable safety without serious adverse events and significant seroconversions in the humoral and cellular immunity panel. The dose of 80 µg is an appropriate dose for injection in the next phases of the trial.

Development of an ELISA Assay for the Determination of SARS-CoV-2 Protein Subunit Vaccine Antigen Content.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) protein subunit vaccine is one of the mainstream technology platforms for the development of COVID-19 vaccines, and most R&D units use the receptor-binding domain (RBD) or spike (S) protein as the main target antigen. The complexity of vaccine design, sequence, and expression systems makes it urgent to establish common antigen assays to facilitate vaccine development. In this study, we report the development of a double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) to determine the antigen content of SARS-CoV-2 protein subunit vaccines based on the United States Pharmacopeia <1220> and ICH (international conference on harmonization) Q14 and Q2 (R2) requirements. A monoclonal antibody (mAb), 20D8, was identified as the detection antibody based on its high RBD binding activity (EC50 = 8.4 ng/mL), broad-spectrum anti-variant neutralizing activity (EC50: 2.7−9.8 ng/mL for pseudovirus and EC50: 9.6−127 ng/mL for authentic virus), good in vivo protection, and a recognized linear RBD epitope (369−379 aa). A porcine anti-RBD polyclonal antibody was selected as the coating antibody. Assay performance met the requirements of the analytical target profile with an accuracy and precision of ≥90% and adequate specificity. Within the specification range of 70−143%, the method capability index was >0.96; the misjudgment probability was <0.39%. The method successfully detected SARS-CoV-2 protein subunit vaccine antigens (RBD or S protein sequences in Alpha, Beta, Gamma, or Delta variants) obtained from five different manufacturers. Thus, we present a new robust, reliable, and general method for measuring the antigenic content of SARS-CoV-2 protein subunit vaccines. In addition to currently marketed and emergency vaccines, it is suitable for vaccines in development containing antigens derived from pre-Omicron mutant strains.

A mathematical model of protein subunits COVID-19 vaccines.

We consider a general mathematical model for protein subunit vaccine with a focus on the MF59-adjuvanted spike glycoprotein-clamp vaccine for SARS-CoV-2, and use the model to study immunological outcomes in the humoral and cell-mediated arms of the immune response from vaccination. The mathematical model is fit to vaccine clinical trial data. We elucidate the role of Interferon-γ and Interleukin-4 in stimulating the immune response of the host. Model results, and results from a sensitivity analysis, show that a balance between the TH1 and TH2 arms of the immune response is struck, with the TH1 response being dominant. The model predicts that two-doses of the vaccine at 28 days apart will result in approximately 85% humoral immunity loss relative to peak immunity approximately 6 months post dose 1.

Recombinant protein subunit COVID-19 vaccine-induced Guillain-Barré Syndrome in an adolescent: A case report.

Guillain-Barré Syndrome (GBS), an autoimmune neurological disease of peripheral nerves, has been causally associated with COVID-19 vaccination in adults. However, no such report has been published so far in children. We describe a 13-year-old female child who presented to the emergency department with complaints of bilateral upper limb, lower limb and truncal weakness over 3 days following first dose of recombinant protein subunit COVID-19 vaccine (Corbevax). Clinical examination and nerve conduction studies showed pure motor axonal polyneuropathy with absent compound muscle action potential (CMAP) in all sampled nerves of upper and lower limbs which was consistent with the diagnosis of GBS after ruling out possible alternative aetiologies. A temporal association between first dose of protein subunit COVID-19 vaccine administered a day prior and symptom onset was noted. The causality assessment using the World Health Organization (WHO) tool for adverse event following immunization (AEFI) assessment indicated vaccine product-related reaction categorized as A1. The patient's clinical condition improved after seven sessions of plasmapheresis. The purpose of this report is to create awareness among health care professionals about COVID-19 vaccine-induced GBS in children as early diagnosis and management can be critical in avoiding complications and improving patient outcomes.

The Rationale Behind the Effectiveness of COVID-19 Vaccines and Associated Immunological Mechanisms

The basic concept of vaccination has been based on engendering an adaptive immune response armed with effective immune cells, memory cells, and cytokines. These elements cooperate to mount either a humoral or a cell-mediated response. Coronavirus disease-2019 vaccines, although diversified, adapted the same objective with the previous vaccines prepared since Edward Jenner's work. The spike surface protein (S) and the receptor binding domain constituted the main antigenic determinants for which the binding antibodies as well as the neutralizing antibodies were secreted. The unprecedented use of mRNA vaccines represented an unmatched breakthrough, which paved the road for a new era of vaccine generation. They showed a substantial ability to elicit antibody secretion with a moderate helper T cell response just after inoculation of the first dose. Besides, the adenoviruses-shuttled vaccines were able to engender a spectrum of polyclonal antibodies including neutralizing antibodies apt to drive a multitude of antibodies-mediated functions and activate T cell immune responses. In either case, the antibody titers as well as lymphocytes-mediated responses were significantly intensified. Deciphering the mechanisms of immune response activation by the inoculated vaccines in addition to the elaboration of innate elements involvement should open the door for a better decryption of the induced immune protection and pave the road for the formulation of a more effective vaccine that surmounts the incessant mutational variation of the viral antigenic attributes. (English) [ FROM AUTHOR]

Thermophilic Filamentous Fungus C1-Cell-Cloned SARS-CoV-2-Spike-RBD-Subunit-Vaccine Adjuvanted with Aldydrogel®85 Protects K18-hACE2 Mice against Lethal Virus Challenge.

SARS-CoV-2 is evolving with increased transmission, host range, pathogenicity, and virulence. The original and mutant viruses escape host innate (Interferon) immunity and adaptive (Antibody) immunity, emphasizing unmet needs for high-yield, commercial-scale manufacturing to produce inexpensive vaccines/boosters for global/equitable distribution. We developed DYAI-100A85, a SARS-CoV-2 spike receptor binding domain (RBD) subunit antigen vaccine expressed in genetically modified thermophilic filamentous fungus, Thermothelomyces heterothallica C1, and secreted at high levels into fermentation medium. The RBD-C-tag antigen strongly binds ACE2 receptors in vitro. Alhydrogel®'85'-adjuvanted RDB-C-tag-based vaccine candidate (DYAI-100A85) demonstrates strong immunogenicity, and antiviral efficacy, including in vivo protection against lethal intranasal SARS-CoV-2 (D614G) challenge in human ACE2-transgenic mice. No loss of body weight or adverse events occurred. DYAI-100A85 also demonstrates excellent safety profile in repeat-dose GLP toxicity study. In summary, subcutaneous prime/boost DYAI-100A85 inoculation induces high titers of RBD-specific neutralizing antibodies and protection of hACE2-transgenic mice against lethal challenge with SARS-CoV-2. Given its demonstrated safety, efficacy, and low production cost, vaccine candidate DYAI-100 received regulatory approval to initiate a Phase 1 clinical trial to demonstrate its safety and efficacy in humans.

Antibodies Induced by Homologous or Heterologous Inactivated (CoronaVac/BBIBP-CorV) and Recombinant Protein Subunit Vaccines (ZF2001) Dramatically Enhanced Inhibitory Abilities against B.1.351, B.1.617.2, and B.1.1.529 Variants.

Safe and effective vaccines for Corona Virus Disease 2019 (COVID-19) can prevent the virus from infecting human populations and treat patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this study, we discuss the inhibitory abilities of primary and booster vaccine-induced antibodies inhibitory ability toward the SARS-CoV-2 wild-type strain, as well as B.1.1.7, B.1.351, P.1, B.1.617.2, and B.1.1.529. We confirmed these antibodies had the strongest inhibitory effects on the wild-type strain and cross-inhibition activities against other mutant strains after two inactivated vaccine doses. However, the B.1.351, B.1.617.2 and B.1.1.529 mutants exhibit antibody resistance in the vaccine serum. Antibodies induced by homologous inactivated vaccines (n = 92) presented more effective inhibition against tested SARS-CoV-2 strains (p < 0.0001), especially B.1.351, B.1.617.2, and B.1.1.529 mutant strains, which had strong immune escape characteristics. In addition, a heterologous booster vaccination (n = 50) of a protein subunit vaccine ZifiVax (ZF2001) significantly restored humoral immune responses and even showed an increasing response against wild-type, B.1.351, B.1.617.2, and B.1.1.529 than homologous inactivated vaccines. Our analysis of the humoral immune response elicited by the different vaccine regimens, including inhibiting antibodies, indicated that a booster, whether homologous or heterologous, could be essential for achieving greater efficacy against SARS-CoV-2.

Safety and immunogenicity of heterologous recombinant protein subunit vaccine (ZF2001) booster against COVID-19 at 3-9-month intervals following two-dose inactivated vaccine (CoronaVac).

Background: In response to SARS-CoV-2 mutations and waning antibody levels after two-dose inactivated vaccines, we assessed whether a third dose of recombinant protein subunit vaccine (ZF2001) boosts immune responses. Methods: An open-label single-center non-random trial was conducted on people aged 18 years and above at five sites in China. All participants received a two-dose inactivated vaccine (CoronaVac) as their prime doses within 3-9 months of the trial. Primary outcomes were safety and immunogenicity, primarily the geometric mean titers (GMTs) of neutralizing antibodies to live wildtype SARS-CoV-2. Results: A total of 480 participants (median age, 51; range 21-84 years) previously vaccinated with two-dose CoronaVac received a third booster dose of ZF2001 3-4, 5-6, or 7-9-months later. The overall incidence of adverse reactions within 30 days after vaccination was 5.83% (28/480). No serious adverse reactions were reported after the third dose of ZF2001. GMTs in the 3-4-, 5-6-, and 7-9-month groups before vaccination were 3.96, 4.60, and 3.78, respectively. On Day 14, GMTs increased to 33.06, 47.51, and 44.12, respectively. After the booster, GMTs showed no significant difference among the three prime-boost interval groups (all P>0.05). Additionally, GMTs in older adults were lower than those in younger adults on Day 14 for the three groups (P=0.0005, P<0.0001, and P<0.0001). Conclusion: Heterologous boosting with ZF2001 was safe and immunogenic, and prime-boost intervals did not affect the immune response. The immune response was weaker in older than younger adults.

Safety, tolerability and immunogenicity of Biological E's CORBEVAX™ vaccine in children and adolescents: A prospective, randomised, double-blind, placebo controlled, phase-2/3 study.

BACKGROUND: After establishing safety and immunogenicity of Biological-E's CORBEVAX™ vaccine in adult population (18-80 years) in Phase 1-3 studies, vaccine is further tested in children and adolescents in this study. METHODS: This is a phase-2/3 prospective, randomised, double-blind, placebo-controlled study evaluating safety, reactogenicity, tolerability and immunogenicity of CORBEVAX™ vaccine in children and adolescents of either gender between <18 to ≥12 years of age in Phase-2 and <18 to ≥5 years of age in Phase-Phase-2/Phase-3 with placebo as a control. This study has two age sub-groups; subgroup-1 with subjects <18 to ≥12 years of age and subgroup-2 with subjects <12 to ≥5 years of age. In both sub groups, eligible subjects (SARS-CoV-2 RT-PCR negative and seronegative at baseline) were randomized to receive either CORBEVAX™ vaccine or Placebo in 3:1 ratio. FINDINGS: The safety profile of CORBEVAX™ vaccine in both pediatric cohorts was comparable to the placebo-control group. Majority of reported adverse events (AEs) were mild in nature. No severe or serious-AEs, medically attended AEs (MAAEs) or AEs of special interest (AESI) were reported during the study period and all reported AEs resolved without any sequelae. In both pediatric age groups, CORBEVAX™ vaccinated subjects showed significant improvement in humoral immune-responses in terms of anti-RBD-IgG concentrations, anti-RBD-IgG1 titers, neutralizing-antibody (nAb)-titers against Ancestral-Wuhan and Delta-strains. Significantly high interferon-gamma immune- response (cellular) was elicited by CORBEVAX™ vaccinated subjects with minimal effect on IL-4 cytokine secretion. INTERPRETATIONS: The safety profile of CORBEVAX™ vaccine in <18 to ≥5 years' children and adolescents was found to be safe and tolerable. Significant increase in anti-RBD-IgG and nAb-titers and IFN-gamma immune-responses were observed post-vaccination in both pediatric age sub-groups. The nAb titers observed in both the pediatric age cohorts were non-inferior to the adult cohort (BECT069 study) in terms of ratio of the GMT's of both the cohorts. This study shows that CORBEVAX™ vaccine is highly immunogenic and can be safely administered to pediatric population as young as 5 years old. The study was prospectively registered with clinical trial registry of India- CTRI/2021/10/037066.

Safety and Immunogenicity of a Heterologous Booster of Protein Subunit Vaccine MVC-COV1901 after Two Doses of Adenoviral Vector Vaccine AZD1222.

We report the safety and immunogenicity results in participants administrated with a booster dose of protein subunit vaccine MVC-COV1901 at 12 (Group A) or 24 (Group B) weeks after two doses of AZD1222 (ChAdOx1 nCoV-19). The administration of the MVC-COV1901 vaccine as a booster dose in both groups was generally safe. There were no serious adverse events related to the intervention as adverse events reported were "mild" or "moderate" in nature. In subjects fully vaccinated with two doses of AZD1222, waning antibody immunity was apparent within six months of the second dose of AZD1222. At one month after the MVC-COV1901 booster dose, those who were vaccinated within 12 weeks after the last AZD1222 dose (Group A) had anti-SARS-CoV-2 spike IgG antibody titers and neutralizing antibody titers which were 14- and 6.5-fold increased, respectively, when compared to the titer levels on the day of the booster dose. On the other hand, fold-increase a month post-booster in people who had a booster 24 weeks after the last AZD1222 dose (Group B) were 19.5 and 14.0 times for anti-SARS-CoV-2 spike IgG antibody titers and neutralizing antibody titers, respectively. Among those who were vaccinated within 12 weeks after the last AZD1222 dose, we also observed 5.2- and 5.6-fold increases in neutralizing titer levels against ancestral strain and Omicron variant pseudovirus after the booster dose, respectively. These results support the use of MVC-COV1901 as a heterologous booster for individuals vaccinated with AZD1222. Furthermore, regardless of the dosing schedule, the combination of AZD1222 primary series and MVC-COV1901 booster can be cost-effective and suitably applied to low- and middle-income countries (LMIC).

Case report: Myocarditis following COVID-19 protein subunit vaccination.

We report findings in a 34-year-old female patient who presented with fulminant myocarditis 8 days after receiving the first dose of the ZF2001 RBD-subunit vaccine against coronavirus disease 2019 (COVID-19). Autopsy showed severe interstitial myocarditis, including multiple patchy infiltrations of lymphocytes and monocytes in the myocardium of the left and right ventricular walls associated with myocyte degeneration and necrosis. This report highlights the details of clinical presentations and autopsy findings of myocarditis after ZF2001 (RBD-subunit vaccine) vaccination. The correlation between vaccination and death due to myocarditis is discussed.