Vaccinia Virus Vectors Research Articles

Exploring future perspectives and pipeline progression in vaccine research and development.

The COVID-19 pandemic had a profound impact on vaccines' Research and Development, on vaccines' market, and on immunization programmes and policies. The need to promptly respond to the health emergency boostered resources' al-location and innovation, while new technologies were made available. Regulatory procedures were revised and expedited, and global production and distribution capacities significantly increased. Aim of this review is to outline the trajectory of research in vaccinology and vaccines' pipeline, highlighting major challenges and opportunities, and projecting future perspectives in vaccine preventables diseases' prevention and control. Narrative review. We comprehensively consulted key biomedical databases including "Medline" and "Embase", preprint platforms, including"MedRxiv" and "BioRxiv", clinical trial registries, selected grey literature sources and scientific reports. Further data and insights were collected from experts in the field. We first reflect on the impact that the COVID-19 had on vaccines' Research and Development, regulatory frameworks, and market, we then present updated figures of vaccines pipeline, by different technologies, comparatively highlighting advantages and disadvantages. We conclude summarizing future perspectives in vaccines' development and immunizations strategies, outlining key challenges, knowledge gaps and opportunities for prevention strategies. COVID-19 vaccines' development has been largely supported by public funding. New technologies and expetited autho-rization and distribution processes allowed to control the pandemic, leading vaccines' market to grow exponentially. In the post-pandemic era investments in prevention are projected to decrease but advancements in technology offer great potential to future immunization strategies. As of 2023, the vaccine pipeline include almost 1,000 candidates, at different Research and Development phase, including innovative recombinant protein vaccines, nucleic acid vaccines and viral vector vaccines. Vaccines' technology platforms development varies by disease. Overall, vaccinology is progressing towards increasingly safe and effective products that are easily manufacturable and swiftly convertible. Vaccine research is rapidly evolving, emerging technologies and new immunization models offer public health new tools and large potential to fight vaccines preventables diseases, with promising new platforms and broadened target populations. Real-life data analysis and operational research is needed to evaluate how such potential is exploited in public health practice to improve population health.

Innovative translational platforms for rapid developing clinical vaccines against COVID-19 and other infectious disease.

A vaccine is a biological preparation that contains the antigen capable of stimulating the immune system to form the defense against pathogens. Vaccine development often confronts big challenges, including time/energy-consuming, low efficacy, lag to pathogen emergence and mutation, and even safety concern. However, these seem now mostly conquerable through constructing the advanced translational platforms that can make innovative vaccines, sometimes, potentiated with a distinct multifunctional VADS (vaccine adjuvant delivery system), as evidenced by the development of various vaccines against the covid-19 pandemic at warp speed. Particularly, several covid-19 vaccines, such as the viral-vectored vaccines, mRNA vaccines and DNA vaccines, regarded as the innovative ones that are rapidly made via the high technology-based translational platforms. These products have manifested powerful efficacy while showing no unacceptable safety profile in clinics, allowing them to be approved for massive vaccination at also warp speed. Now, the proprietary translational platforms integrated with the state-of-the-art biotechnologies, and even the artificial intelligence (AI), represent an efficient mode for rapid making innovative clinical vaccines against infections, thus increasingly attracting interests of vaccine research and development. Herein, the advanced translational platforms for making innovative vaccines, together with their design principles and immunostimulatory efficacies, are comprehensively elaborated.

Expected Usefulness of Fourth Dose of COVID-19 Vaccine for Patients with Underlying Solid Tumor who Previously Received the Primary Heterologous COVID-19 Vaccine

AbstractCoronavirus disease 2019 (COVID-19) immunization frequently requires two standard doses. Due to the likelihood that the population may lose immunity after receiving a standard mass vaccination and the potential for the introduction of a new strain, several scientists are currently advocating the use of a booster dosage of the vaccine.The authors of this retrospective study used a clinical model for immune response prediction to forecast how solid cancer patients will respond to the fourth dosage of the COVID-19 immunization. In the case of homologous primary backgrounds, the prospective rates of extension of protective efficacy for using viral vector and messenger ribonucleic acid (mRNA) COVID-19 vaccines for vaccinees with underlying solid tumor are equal to 11.5 and 16.5%, respectively. In the event of heterologous primary backgrounds, the prospective rates of extension of protective efficacy for using viral vector and mRNA COVID-19 vaccines are equal to 2.2 and 7.2%, respectively, for patients with underlying solid cancer. In conclusion, the fourth dose of the COVID-19 vaccine regimen had an effect on the immunogenicity of vaccine recipients with underlying malignancy.

Intradermal Fractional ChAdOx1 nCoV-19 Booster Vaccine Induces Memory T Cells: A Follow-Up Study.

The administration of viral vector and mRNA vaccine booster effectively induces humoral and cellular immune responses. Effector T cell responses after fractional intradermal (ID) vaccination are comparable to those after intramuscular (IM) boosters. Here, we quantified T cell responses after booster vaccination. ChAdOx1 nCoV-19 vaccination induced higher numbers of S1-specific CD8+ memory T cells, consistent with the antibody responses. Effector memory T cell phenotypes elicited by mRNA vaccination showed a similar trend to those elicited by the viral vector vaccine booster. Three months post-vaccination, cytokine responses remained detectable, confirming effector T cell responses induced by both vaccines. The ID fractional dose of ChAdOx1 nCoV-19 elicited higher effector CD8+ T cell responses than IM vaccination. This study confirmed that an ID dose-reduction vaccination strategy effectively stimulates effector memory T cell responses. ID injection could be an improved approach for effective vaccination programs.

Current Progress of Severe Fever with Thrombocytopenia Syndrome Virus (SFTSV) Vaccine Development.

SFTSV is an emerging tick-borne virus causing hemorrhagic fever with a case fatality rate (CFR) that can reach up to 27%. With endemic infection in East Asia and the recent spread of the vector tick to more than 20 states in the United States, the SFTSV outbreak is a globally growing public health concern. However, there is currently no targeted antiviral therapy or licensed vaccine against SFTSV. Considering the age-dependent SFTS pathogenesis and disease outcome, a sophisticated vaccine development approach is required to safeguard the elderly population from lethal SFTSV infection. Given the recent emergence of SFTSV, the establishment of animal models to study immunogenicity and protection from SFTS symptoms has only occurred recently. The latest research efforts have applied diverse vaccine development approaches-including live-attenuated vaccine, DNA vaccine, whole inactivated virus vaccine, viral vector vaccine, protein subunit vaccine, and mRNA vaccine-in the quest to develop a safe and effective vaccine against SFTSV. This review aims to outline the current progress in SFTSV vaccine development and suggest future directions to enhance the safety and efficacy of these vaccines, ensuring their suitability for clinical application.

The Development of a Rabies Virus-Vectored Vaccine against Borrelia burgdorferi, Targeting BBI39.

Lyme disease (LD) is the most common tick-borne illness in the United States (U.S.), Europe, and Asia. Borrelia burgdorferi, a spirochete bacterium transmitted by the tick vector Ixodes scapularis, causes LD in the U.S. If untreated, Lyme arthritis, heart block, and meningitis can occur. Given the absence of a human Lyme disease vaccine, we developed a vaccine using the rabies virus (RABV) vaccine vector BNSP333 and an outer surface borrelial protein, BBI39. BBI39 was previously utilized as a recombinant protein vaccine and was protective in challenge experiments; therefore, we decided to utilize this protective antigen in a rabies virus-vectored vaccine against Borrelia burgdorferi. To incorporate BBI39 into the RABV virion, we generated a chimeric BBI39 antigen, BBI39RVG, by fusing BBI39 with the final amino acids of the RABV glycoprotein by molecular cloning and viral recovery with reverse transcription genetics. Here, we have demonstrated that the BBI39RVG antigen was incorporated into the RABV virion via immunofluorescence and Western blot analysis. Mice vaccinated with our BPL inactivated RABV-BBI39RVG (BNSP333-BBI39RVG) vaccine induced high amounts of BBI39-specific antibodies, which were maintained long-term, up to eight months post-vaccination. The BBI39 antibodies neutralized Borrelia in vaccinated mice when challenged with Borrelia burgdorferi by either syringe injection or infected ticks and they reduced the Lyme disease pathology of arthritis in infected mouse joints. Overall, the RABV-based LD vaccine induced more and longer-term antibodies compared to the recombinant protein vaccine. This resulted in lower borrelial RNA in RABV-based vaccinated mice compared to recombinant protein vaccinated mice. The results of this study indicate the successful use of BBI39 as a vaccine antigen and RABV as a vaccine vector for LD.

Superior mesenteric vein thrombosis due to COVID-19 vaccination: a case report

BackgroundThe worldwide vaccination response to COVID-19 has been associated with rare thrombotic complications, including the case of postvaccination splanchnic venous thrombosis we report here.Case presentationAn 80-year-old Japanese male with abdominal pain presented to our hospital six days after receiving a dose of the COVID-19 messenger ribonucleic acid vaccine. Abdominal computed tomography showed localized edema of the small intestine, increased density of the surrounding adipose tissue, and a thrombus in the superior mesenteric vein. Conservative inpatient treatment with unfractionated heparin relieved the thrombosis, and the patient is currently receiving oral apixaban as an outpatient.ConclusionReported cases of thrombosis after COVID-19 vaccination typically have been associated with viral vector vaccines, with few reports of thrombosis induced by mRNA vaccines. The potential for venous thrombosis should be explored when patients present with abdominal pain soon after COVID-19 vaccination.

Comparison of the Efficacy of Different Schemes for Using Recombinant Vector Vaccines against Ebola Fever, Based on Vaccinia Virus, MVA Strain

The aim of this review was to investigate the use of the vaccines based on vaccinia virus, MVA stain, and adenovirus vectors for the prevention of Ebola virus disease. The recombinant MVA strains expressing antigen determinants of Filoviridae family representatives were assessed as possible candidates for vaccine preparations. Application of this virus as a vaccine vector is conditioned by the absence of herd immunity to smallpox and its safety for healthy adult volunteers, children, adolescents, individuals suffering from tuberculosis, persons aged 56–80 years, people with diagnosed atopic dermatitis, AIDS. Furthermore, immunization with the vaccine on the basis of vaccinia virus, MVA strain, does not cause complications associated with cardiovascular diseases. Preclinical trials on immunogenicity and protective efficiency were carried out on immune-competent and immune-compromised mice; guinea pigs adapted to Ebola virus; rhesus macaques and cynomolgus monkeys. Presented are the results of experiments on the creation of vaccines expressing either only viral glycoprotein or viral glycoprotein and structural protein Vp40. Given that Ebola fever and other filovirus infection outbreaks are hard to predict, multivalent vaccines that would be able to provide protection against all filovirus species were designed. Clinical trials on simultaneous use of the vaccines based on recombinant adenovirus vectors and MVA strain showed more pronounced safety of vaccines on the basis of recombinant MVA strain. Studies of humoral and T-cell immune responses have revealed that this vector is more suitable for booster vaccination in case of heterologous prime/booster immunization scheme. Vaccination regimens for forming strong durable immune responses have been analyzed. Epidemiological modeling provided evidence that preventive immunization leading to long-term immunity in healthy population in areas of high epidemic risk will be of greater benefit in terms of controlling future outbreaks compared to ring immunization that was effective during smallpox eradication campaign. Increased immunity level, induced by prime/booster vaccination, persisting for a long period of time, will have an advantage over accelerated ring immunization; when the duration of protection is more significant than the speed it is formed at.

COVID-19 vaccine-associated vasculitis: A systematic review.

Post-COVID-19 vaccine-associated vasculitis stands as one of the most serious side effects attributed to COVID-19 vaccines. This complication encompasses diverse manifestations which vary in presentation and severity. Moreover, it can impact patients across all age groups, with a notably elevated incidence in the elderly. This systematic review seeks to review and evaluate the spectrum of vasculitis manifestations linked to COVID-19 vaccination. A systematic review of the literature was done by searching through PubMed, Google Scholar, and Scopus up to October 2022. Articles including data about sex, age at diagnosis, vasculitis clinical manifestations, type of vaccination, most commonly used investigations, comorbid medical conditions, treatments, and clinical outcomes were included in the final analysis. Furthermore, vasculitis flare-ups post-vaccination were considered part of this review. A total number of 117 studies describing 158 patients developing vasculitis following COVID-19 vaccination were included in the final analysis. Among the patients who developed vasculitis, the most administered type of vaccination was the mRNA vaccine subtype (n = 103), followed by the viral vector vaccines (n = 42) and inactivated viral vaccines (n = 10). On the other hand, about 38% of vasculitis-related symptoms occurred after the administration of the first dose of the vaccine and 37% occurred after taking the second dose. The skin (60.7%) and the kidneys (27.8%) were the most affected organs and complete remission was achieved in 111 patients (70%), while partial remission occurred in 11% of the patient population. COVID-19 vaccine-induced vasculitis is a rare occurrence associated with COVID-19 vaccines. It generally presents a favorable prognosis and outcomes for the vast majority of patients, ultimately leading to full remission within days. This review emphasizes the notion that the advantages of COVID-19 vaccines outweigh the potential risks, particularly for individuals with compromised immune systems.

An Overview of Future Development Methods of Infectious Bronchitis Vaccines

Vaccines are major disease-controlling tools in human and animal practices. Vaccination controlled or even eradicated a long list of diseases worldwide. Classic viral vaccines are usually composed of live or inactivated whole viruses and have been produced for many years. However, they are unsuccessful, especially in persistent infections, fast-evolving viruses, complex and compound antigens, and emerging agents. Novel vaccine development technologies such as DNA, protein, or viral vector vaccines have revolutionized vaccine development and opened a new horizon for study and research in vaccine research and production vision. Newly-developed vaccines, or even most traditional ones, are based on new technologies, especially in human diseases where cost and complications in production can be ignored. However, in animal health, especially for commercial poultry production, the cost of development, simplicity, and mass application of large-scale production cannot be overlooked. In recent years, the significance of producing novel vaccines has been highlighted in parallel with technological advancement, especially with emerging novel variants of infectious bronchitis viruses—serious poultry pathogens for years. In this review, we will introduce some studies on novel vaccine development techniques and investigate the results of those vaccines in the protection of chickens and their clinical outcomes.

Recurring SARS-CoV-2 variants: an update on post-pandemic, co-infections and immune response.

The post-pandemic era following the global spread of the SARS-CoV-2 virus has brought about persistent concerns regarding recurring coinfections. While significant strides in genome mapping, diagnostics, and vaccine development have controlled the pandemic and reduced fatalities, ongoing virus mutations necessitate a deeper exploration of the interplay between SARS-CoV-2 mutations and the host's immune response. Various vaccines, including RNA-based ones like Pfizer and Moderna, viral vector vaccines like Johnson & Johnson and AstraZeneca, and protein subunit vaccines like Novavax, have played critical roles in mitigating the impact of COVID-19. Understanding their strengths and limitations is crucial for tailoring future vaccines to specific variants and individual needs. The intricate relationship between SARS-CoV-2 mutations and the immune response remains a focus of intense research, providing insights into personalized treatment strategies and long-term effects like long-COVID. This article offers an overview of the post-pandemic landscape, highlighting emerging variants, summarizing vaccine platforms, and delving into immunological responses and the phenomenon of long-COVID. By presenting clinical findings, it aims to contribute to the ongoing understanding of COVID-19's progression in the aftermath of the pandemic.

Expression of recombinant Florida clade 2 hemagglutinin in baculovirus expression system: A step for subunit vaccine development against H3N8 equine influenza virus.

Equine influenza (EI) is a transmissible viral respiratory sickness of the Equidae family. Two viruses, H7N7 and H3N8 caused EI; however, H7N7 has not been detected for decades. H3N8 has circulated and bifurcated into Eurasian and American lineages. The latter subsequently diversified into Kentucky, South America, and Florida sub-lineages. Florida clade 1 (FC1) and Florida clade 2 (FC2) strains are the only circulating EI viruses (EIVs) in the meantime. Immunization is considered the major means for the prevention and control of EI infection. Using disparate technologies and platforms, several vaccines have been developed and commercialized. According to the recommendations of the World Organization for Animal Health (WOAH), all commercial vaccines shall comprise representatives of both FC1 and FC2 strains. Unfortunately, most of the commercially available vaccines were not updated to incorporate a representative of FC2 strains. The purpose of this research was to develop a new EI vaccine candidate that incorporates the hemagglutinin (HA) antigen from the currently circulating FC2. In this study, we report the expression of the full-length recombinant HA gene of FC2 in the baculovirus expression system. The HA recombinant protein has been proven to maintain its biological characteristics by hemadsorption (HAD) and hemagglutination tests. Moreover, using a reference-specific serum, the specificity of the HA has been confirmed through the implementation of immunoperoxidase and western immunoblotting assays. In conclusion, we report the expression of specific biologically active recombinant HA of FC2, which would act as a foundation for the generation of an updated EI subunit or virus vector vaccine candidates.

Universal Vaccine Development Against COVID-19 and Influenza

Universal vaccines appeared as a favorable solution for the rapid mutation of viruses that cause pandemics. Sufficient immune protection, safe and efficient production methods, and low-cost funding are ideal properties for universal vaccines. Targeting conserved regions, use of adjuvants, cell-mediated immunity approaches, virus-like particles, and multimeric presentation of viral antigens are strategies to enhance vaccine Immunogenicity. Different types of vaccines have been put into clinical trials, such as messenger RNA vaccines, on-replicating viral vector vaccines, and recombinant protein-based vaccines, which are proven to suit the needs of universal vaccine investigation. Moreover, this article introduces the universal vaccine development of SARS-CoV-2 and influenza variants, their vaccine candidates, research results, and the challenges faced. Universal vaccines are the trend of future viral protection, with more and more new technologies entering the field, a universal vaccine is within reach.

Effect of leucine as an aerosolization enhancer on the bioactivity of spray dried viral-vectored vaccines for inhalation

We explore the advantages and disadvantages of l-leucine on spray dried vaccine formulations.

Vaccinating against a Novel Pathogen: A Critical Review of COVID-19 Vaccine Effectiveness Evidence.

We study the experience with COVID-19 vaccination of an initially naïve population, which can inform planning for vaccination against the next novel, highly transmissible pathogen. We focus on the first two pandemic years (wild strain through Delta), because after the Omicron wave in early 2022, very few people were still SARS-CoV-2-naïve. Almost all were vaccinated, infected, or often both. We review the evidence on COVID-19 vaccine effectiveness (VE) and waning effectiveness over time and the relative effectiveness of the four principal vaccines used in developed Western countries: BNT162b2 (Pfizer-BioNTech), mRNA1273 (Moderna), Ad26.CoV2.S (Johnson&Johnson), and ChAdOx1-S (AstraZeneca). As a basis for our analysis, we conducted a PRISMA-compliant review of all studies on PubMed through 15 August 2022, reporting VE against four endpoints for these four vaccines: any infection, symptomatic infection, hospitalization, and death. The mRNA vaccines (BNT162b2, mRNA1273) had high initial VE against all endpoints but protection waned after approximately six months, with BNT162b2 declining faster than mRNA1273. Both mRNA vaccines outperformed the viral vector vaccines (Ad26.CoV2.S and ChAdOx1-S). A third "booster" dose, roughly six months after the initial doses, substantially reduced symptomatic infection, hospitalization, and death. In hindsight, a third dose should be seen as part of the normal vaccination schedule. Our analysis highlights the importance of the real-time population-level surveillance needed to assess evidence for waning, and the need for rapid regulatory response to this evidence.

Risk of Bell's Palsy after COVID-19 vaccination

At the close of 2019, a global health crisis known as COVID-19, or coronavirus (2019-nCoV), broke out. Vaccination is used as a means of prevention. The COVID-19 vaccines may be categorized into four groups: viral vector, entire virus, subunit protein, and nucleic vaccines. Upon evaluating the advantages of vaccinations, it becomes evident that there are adverse side effects that may develop. Bell's palsy is regarded as a significant adverse reaction after immunization. This observational essay aims to consolidate knowledge about the SARS-CoV-2 infection and its association with the risk of Bell's palsy after COVID-19 vaccination.

Research Progress in Respiratory Syncytial Virus Vaccines

In addition to being a substantial source of morbidity and mortality in older persons, respiratory syncytial virus (RSV) is a major contributor to lower respiratory tract infections in newborns and young children. Worldwide, there has been a lot of research done to provide safe and effective vaccinations against this common infection because there isn't an approved RSV vaccine. A succinct summary of current developments in RSV vaccine research is given in this abstract. Many vaccinations have reached the clinical testing stage and shown promising benefits. Live attenuated vaccines, nanoparticle vaccines, and viral vector vaccines are the three primary categories of current vaccination techniques. Additionally, the production of specific RSV antibodies such as MEDI8897 and polyclonal immunoglobulin RI-002 is being evaluated as an important research antibodies for avoiding RSV infection. The continuous dedication to RSV vaccine development gives optimism for the future prevention of RSV-related disorders across all age groups, despite the fact that challenges still exist, particularly ERD (Enhanced respiratory disease).

Therapeutic Vaccines in Breast Cancer

Breast cancer (BC) is a major worldwide health issue, characterised by an increasing occurrence in both males and females. The classification of breast cancer subgroups is determined by variations in hormone receptor expression. Although traditional breast cancer therapies, including chemotherapy, surgery, and radiotherapy, have demonstrated effectiveness in the treatment of patients, they are frequently associated with significant adverse effects and recurrence. The emergence of therapeutic vaccines has become a promising option for the field of immunotherapy. These vaccines enhance the body’s immune system to identify and eliminate cancerous tumour cells. The current approach to vaccine therapy for breast cancer focuses on the targeting of two main categories of antigens: tumour associated antigens and tumour specific antigens. Excitingly, multiple vaccine strategies for breast cancer treatment have been employed, all of which have demonstrated promise and effectiveness in clinical studies. Currently, proposed vaccine types include peptide-based vaccines, whole tumour cell vaccines, DNA/RNA-based vaccines, dendritic cell vaccines, and viral-vector vaccines, etc. This review examined the present state of different types of vaccines in breast cancer therapy, including the therapeutic mechanism and the treatment outcomes.

MRNA vaccines for COVID-19 are safe and clinically effective in patients with cardiac amyloidosis

IntroductionAmyloidosis is a rare disease in which malformed proteins are deposited in tissues occurring mostly commonly in older age. These deposits can lead to severe organ dysfunction e.g. in the myocardium with great impact on prognosis. The Covid-19 pandemic has caused excess mortality worldwide since 2020. Risk factors for a severe course include pre-existing cardiac diseases like heart failure and advanced age. Therefore, vaccination against Sars-CoV2 viruses is highly recommended for patients with cardiac amyloidosis. However, since there are no specific data on mRNA vaccines in patients with cardiac amyloidosis, some patients have concerns about cardiac adverse events following immunization (AEFI), such as myocarditis. PurposeThe purpose of the study is to assess the safety and efficacy of mRNA vaccines in patients with cardiac amyloidosis. MethodsPatients of the Amyloidosis Center Charité Berlin (ACCB) were assessed about the vaccination, its tolerability and clinical effectiveness. To date, we included 62 patients (54 men) with a median age of 82,5 years (range 37 to 92). 46 patients had wtATTR amyloidosis, ten patients had hATTR amyloidosis, and six patients had AL amyloidosis. The mean systolic left ventricular function was 51% (range 30 to 62) with a mean global strain of −11,5% (range −18,5 to −3,1). The mean NT-pro-BNP was 1145 ng/l (range 24 to 48297). Results59 patients were triple vaccinated and three patients so far are double vaccinated. Three of the patients were unvaccinated. 171 of the vaccine doses administered were mRNA vaccines and eight doses were a viral vector-vaccine. None of the patients reported severe side effects. Thirteen patients reported feeling of pressure and pain at the injection site after vaccination and four patients had fever of maximum two days, eight patients reported lower general condition of maximum five days. One patient reported malaise for 14 days after each vaccination, which resolved spontaneously. There was no clinical or laboratory evidence of suspected vaccine-induced myocarditis. Five patients reported of a COVID-19 breakthrough infection, all of which with a mild course of disease. None of the patients had symptoms of worsening heart failure in temporal relation to the vaccination.Most of the vaccinations (103) were performed at an official vaccination center, 59 were performed at a general practitioner. ConclusionIn patients with cardiac amyloidosis, mRNA vaccines for COVID-19 are safe with respect to severe cardiac adverse events and show effective protection against clinically relevant SARS-CoV2 infection.

Immunogenicity and durability against Omicron BA.1, BA.2 and BA.4/5 variants at 3–4 months after a heterologous COVID-19 booster vaccine in healthy adults with a two-doses CoronaVac vaccination

BackgroundSeveral countries have authorized a booster vaccine campaign to combat the spread of COVID-19. Data on persistence of booster vaccine‐induced immunity against new Omicron subvariants are still limited. Therefore, our study aimed to determine the serological immune response of COVID-19 booster after CoronaVac-priming. MethodsA total of 187 CoronaVac-primed participants were enrolled and received an inactivated (BBIBP), viral vector (AZD1222) or mRNA vaccine (full-/half-dose BNT162B2, full-/half-dose mRNA-1273) as a booster dose. The persistence of humoral immunity both binding and neutralizing antibodies against wild-type and Omicron was determined on day 90–120 after booster. ResultsA waning of total RBD immunoglobulin (Ig) levels, anti-RBD IgG, and neutralizing antibodies against Omicron BA.1, BA.2, and BA.4/5 variants was observed 90–120 days after booster vaccination. Participants who received mRNA-1273 had the highest persistence of the immunogenicity response, followed by BNT162b2, AZD1222, and BBIBP-CorV. The responses between full and half doses of mRNA-1273 were comparable. The percentage reduction of binding antibody ranged from 50 % to 75 % among all booster vaccine. ConclusionsThe antibody response substantially waned after 90–120 days post-booster dose. The heterologous mRNA and the viral vector booster demonstrated higher detectable rate of humoral immune responses against the Omicron variant compared to the inactivated BBIBP booster. Nevertheless, an additional fourth dose is recommended to maintain immune response against infection.