Current progress and challenges in the design and development of a successful COVID-19 vaccine

Evaluation of Immune Response to Mucosal Immunization with an Oral Probiotic-Based Vaccine in Mice: Potential for Prime-Boost Immunization against SARS-CoV-2

Following the conclusion of the COVID-19 pandemic, the persistent genetic variability in the virus and its ongoing circulation within the global population necessitate the enhancement of existing preventive vaccines and the development of novel ones. A while back, we engineered an orally administered probiotic-based vaccine, L3-SARS, by integrating a gene fragment that encodes the spike protein S of the SARS-CoV-2 virus into the genome of the probiotic strain E. faecium L3, inducing the expression of viral antigen on the surface of bacteria. Previous studies demonstrated the efficacy of this vaccine candidate in providing protection against the virus in Syrian hamsters. In this present study, utilizing laboratory mice, we assess the immune response subsequent to immunization via the gastrointestinal mucosa and discuss its potential as an initial phase in a two-stage vaccination strategy. Our findings indicate that the oral administration of L3-SARS elicits an adaptive immune response in mice. Pre-immunization with L3-SARS enhances and prolongs the humoral immune response following a single subcutaneous immunization with a recombinant S-protein analogous to the S-insert of the coronavirus in Enterococcus faecium L3.

Africa (COVID-19) Vaccine Technology Transfer: Where Are We?

The rampant spread of the COVID-19 infection poses a grave and formidable challenge to global healthcare, with particular concern to the inhabitants of the African continent. In response to these pressing concerns, different strategies have been employed to combat the emergence of this insidious disease, encompassing crucial measures such as physical distancing, the utilization of face masks, meticulous hand hygiene, and widespread vaccination campaigns. Nevertheless, the economic realities faced by numerous African nations, characterized by their classification as "low-income countries (LICs)", present a formidable barrier to accessing and distributing approved vaccines to their populations. Moreover, it is essential to discuss the hesitancy of the European Union (EU) in releasing intellectual property rights associated with the transfer of vaccine technology to Africa. While the EU has been a key player in global efforts to combat the pandemic, there has been reluctance in sharing valuable knowledge and resources with African countries. This hesitancy raises concerns about equitable vaccine access and the potential for a prolonged health crisis in Africa. This review underscores the urgent imperative and need of establishing localized vaccine development and production facilities within Africa, necessitating the active involvement of governments and collaborative partnerships to achieve this crucial objective. Furthermore, this review advocates for the exploration of viable avenues for the transfer of vaccine technology as a means to facilitate equitable vaccine access across the African continent and also the cruciality and the need for the EU to reconsider its stance and actively engage in transferring vaccine technology to Africa through sharing intellectual property. The EU can contribute to the establishment of localized vaccine production facilities on the continent, which will not only increase vaccine availability but also promote self-sufficiency and resilience in the face of future health emergencies.

Fast-track development of vaccines for SARS-CoV-2: The shots that saved the world

In December 2019, an outbreak emerged of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which leads to coronavirus disease 2019 (COVID-19). The World Health Organisation announced the outbreak a global health emergency on 30 January 2020 and by 11 March 2020 it was declared a pandemic. The spread and severity of the outbreak took a heavy toll and overburdening of the global health system, particularly since there were no available drugs against SARS-CoV-2. With an immediate worldwide effort, communication, and sharing of data, large amounts of funding, researchers and pharmaceutical companies immediately fast-tracked vaccine development in order to prevent severe disease, hospitalizations and death. A number of vaccines were quickly approved for emergency use, and worldwide vaccination rollouts were immediately put in place. However, due to several individuals being hesitant to vaccinations and many poorer countries not having access to vaccines, multiple SARS-CoV-2 variants quickly emerged that were distinct from the original variant. Uncertainties related to the effectiveness of the various vaccines against the new variants as well as vaccine specific-side effects have remained a concern. Despite these uncertainties, fast-track vaccine approval, manufacturing at large scale, and the effective distribution of COVID-19 vaccines remain the topmost priorities around the world. Unprecedented efforts made by vaccine developers/researchers as well as healthcare staff, played a major role in distributing vaccine shots that provided protection and/or reduced disease severity, and deaths, even with the delta and omicron variants. Fortunately, even for those who become infected, vaccination appears to protect against major disease, hospitalisation, and fatality from COVID-19. Herein, we analyse ongoing vaccination studies and vaccine platforms that have saved many deaths from the pandemic.

Dendritic cell-based vaccine: the state-of-the-art vaccine platform for COVID-19 management

INTRODUCTION

A correlation between new coronaviruses and host immunity, as well as the role of defective immune function in host response, would be extremely helpful in understanding coronavirus disease (COVID-19) pathogenicity, and a coherent structure of treatments and vaccines. As existing vaccines may be inadequate for new viral variants emerging in various regions of the world, it is a vital requirement for fresh and effective therapeutic alternatives.

AREA COVERED

Immunotherapy may give a viable protective option for COVID-19, a disease that is currently a big burden on global health and economic systems. Herein, we have outlined three dendritic cell (DC)-based vaccines for COVID-19 which are in human clinical trials and have shown encouraging outcomes.

EXPERT OPINION

With existing knowledge of the virus, and the nature of DC, DC-based vaccines may be proven to be effective in inducing long-lasting protective immunity, especially T cell responses.

Exploring whole proteome to contrive multi-epitope-based vaccine for NeoCoV: An immunoinformtics and in-silico approach

Neo-Coronavirus (NeoCoV) is a novel Betacoronavirus (β-CoVs or Beta-CoVs) discovered in bat specimens in South Africa during 2011. The viral sequence is highly similar to Middle East Respiratory Syndrome, particularly that of structural proteins. Thus, scientists have emphasized the threat posed by NeoCoV associated with human angiotensin-converting enzyme 2 (ACE2) usage, which could lead to a high death rate and faster transmission rate in humans. The development of a NeoCoV vaccine could provide a promising option for the future control of the virus in case of human infection. In silico predictions can decrease the number of experiments required, making the immunoinformatics approaches cost-effective and convenient. Herein, with the aid of immunoinformatics and reverse vaccinology, we aimed to formulate a multi-epitope vaccine that may be used to prevent and treat NeoCoV infection. Based on the NeoCoV proteins, B-cell, cytotoxic T lymphocyte (CTL), and helper T lymphocyte (HTL) epitopes were shortlisted. Four vaccines (Neo-1-4) were devised by fusing shortlisted epitopes with appropriate adjuvants and linkers. The secondary and three-dimensional structures of final vaccines were then predicted. The binding interactions of these potential vaccines with toll-like immune receptors (TLR-2, TLR-3, and TLR-4) and major histocompatibility complex molecules (MHC-I and II) reveal that they properly fit into the receptors' binding domains. Besides, Neo-1 and Neo-4 vaccines exhibited better docking energies of -101.08 kcal/mol and -114.47 kcal/mol, respectively, with TLR-3 as compared to other vaccine constructs. The constructed vaccines are highly antigenic, non-allergenic, soluble, non-toxic, and topologically assessable with good physiochemical characteristics. Codon optimization and in-silico cloning confirmed efficient expression of the designed vaccines in Escherichia coli strain K12. In-silico immune simulation indicated that Neo-1 and Neo-4 vaccines could induce a strong immune response against NeoCoV. Lastly, the binding stability and strong binding affinity of Neo-1 and Neo-4 with TLR-3 receptor were validated using molecular dynamics simulations and free energy calculations (Molecular Mechanics/Generalized Born Surface Area method). The final vaccines require experimental validation to establish their safety and effectiveness in preventing NeoCoV infections.

Frequency of Ipsilateral Axillary Lymphadenopathy After the Inactivated COVID-19 Vaccine

OBJECTIVE

During COVID-19 vaccine development studies, vaccines' efficacy and safety profiles should be carefully investigated. Only a few studies have shown that the COVID-19 vaccine can cause axillary lymphadenopathy on the injection arm. This study aimed to investigate the incidence of axillary lymphadenopathy and imaging findings using B-mode and Doppler ultrasonography (US) examinations in volunteers who had recently been vaccinated against COVID-19.

METHODS

The ipsilateral and contralateral axillae of 101 volunteers who received the COVID-19 vaccine were evaluated using B-mode and Doppler US examinations. The volunteers were asked when and to which arm the vaccine had been applied, and the type and dose of the vaccine were recorded. It was also questioned whether the individual experienced any side effects after vaccination, such as pain, tenderness, fever, and redness at the injection site. In addition, the demographic data of the participants, such as age and gender were recorded.

RESULTS

The B-mode US examinations revealed that the long- and short-axis diameters, size, cortical thickness and asymmetric cortical thickening of the left axillary lymph nodes were significantly higher compared to the right side in individuals having received the CoronaVac vaccine (p<0.05). When the individuals were evaluated separately according to gender, the frequency of cortical thickness and asymmetric cortical thickening in the left axillary lymph nodes was higher than on the right side in both males and females (p=0.011).

CONCLUSION

It should be kept in mind that ipsilateral reactive lymphadenopathy may develop after the COVID-19 vaccine. This knowledge can prevent unnecessary axillary lymph node biopsies.

The Immune Response to SARS-CoV-2: Mechanisms, Aging, Sequelae and Vaccines

This review seeks to clarify the factors involved in the various immune responses to SARS-CoV-2 infection and the mechanisms that influence the development of COVID-19 with severe evolution. The innate immune response that evolves against SARS-CoV-2 in a complex way is highlighted, integrating multiple pathways by coronaviruses to evade it, in addition to characterizing the adaptive immune response, which can lead to an effective immune response or can contribute to immunopathological imbalance. In turn, host-dependent biomarkers such as age, gender, ABO blood group, and risk factors that contribute to the critical and varied progress of COVID-19 immunopathogenesis were analyzed. Finally, the potential vaccine candidates are presented, capable of generating immune protection with humoral and/or cellular neutralizing responses, in favor of blocking and destroying both the new human coronavirus and its variants, which cause the current pandemic.

T helper type (Th1/Th2) responses to SARS-CoV-2 and influenza A (H1N1) virus: From cytokines produced to immune responses

Cytokines produced by T helper cells (Th cells) have essential roles in the body's defense against viruses. Type 1 T helper (Th1) cells are essential for the host defense toward intracellular pathogens while T helper type 2 (Th2) cells are considered to be critical for the helminthic parasites' elimination swine-origin influenza A (H1N1) virus, a disease led to an epidemic in 2009 and rapidly spread globally via human-to-human transmission. Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused a global pandemic in 2020 and is a serious threat to the public health. Pulmonary immunopathology is the leading cause of death during influenza and SARS-CoV-2 epidemics and pandemics. Influenza and SARS-CoV-2 cause high levels of cytokines in the lung. Both inadequate levels and high levels of specific cytokines can have side effects. In this literature review article, we want to compare the Th1 and Th2 cells responses in SARS-CoV-2 and H1N1.

COVID-19 vaccines development in Africa: a review of current situation and existing challenges of vaccine production

Following the development of the coronavirus disease 2019 (COVID-19) vaccines and the launching of vaccination, the World Health Organization has reported that the African Continent is lagging in the race to vaccinate its population against the deadly virus. The Continent has received a limited number of vaccines, implying that vaccine production needs to be scaled up in Africa. In this review, we summarize the current situation concerning COVID-19 vaccine development in Africa, progress made, challenges faced in vaccine development over the years and potential strategies that will harness vaccine production success.

COVID-19 Vaccination: The Mainspring of Challenges and the Seed of Remonstrance

As of March 2020, the time when the coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) became a pandemic, our existence has been threatened and the lives of millions have been claimed. With this ongoing global issue, vaccines are considered of paramount importance in curtailing the outbreak and probably a prime gamble to bring us back to 'ordinary life'. To date, more than 200 vaccine candidates have been produced, many of which were approved by the Food and Drug Administration (FDA) for emergency use, with the research and discovery phase of their production process passed over. Capering such a chief practice in COVID-19 vaccine development, and manufacturing vaccines at an unprecedented speed brought many challenges into play and raised COVID-19 vaccine remonstrance. In this review, we highlight relevant challenges to global COVID-19 vaccine development, dissemination, and deployment, particularly at the level of large-scale production and distribution. We also delineate public perception on COVID-19 vaccination and outline the main facets affecting people's willingness to get vaccinated.

Cross-neutralizing antibodies bind a SARS-CoV-2 cryptic site and resist circulating variants

The emergence of numerous variants of SARS-CoV-2, the causative agent of COVID-19, has presented new challenges to the global efforts to control the COVID-19 pandemic. Here, we obtain two cross-neutralizing antibodies (7D6 and 6D6) that target Sarbecoviruses' receptor-binding domain (RBD) with sub-picomolar affinities and potently neutralize authentic SARS-CoV-2. Crystal structures show that both antibodies bind a cryptic site different from that recognized by existing antibodies and highly conserved across Sarbecovirus isolates. Binding of these two antibodies to the RBD clashes with the adjacent N-terminal domain and disrupts the viral spike. Both antibodies confer good resistance to mutations in the currently circulating SARS-CoV-2 variants. Thus, our results have direct relevance to public health as options for passive antibody therapeutics and even active prophylactics. They can also inform the design of pan-sarbecovirus vaccines.

Investigating the Links Between Vaccination Against COVID-19 and Public Attitudes Toward Protective Countermeasures: Implications for Public Health

The COVID-19 pandemic caused by the novel coronavirus, SARS-CoV-2, is spreading globally at an unprecedented rate. To protect the world against this devastating catastrophe, vaccines for SARS-CoV-2 have been produced following consistent clinical trials. However, the durability of a protective immune response due to vaccination has not been confirmed. Moreover, COVID-19 vaccination against SARS-CoV-2 is not 100% guaranteed, as new variants arise due to mutations. Consequently, health officials are pleading with the public to take extra precautions against the virus and continue wearing masks, wash hands, and observe physical distancing even after vaccination. The current research collected data from 4,540 participants (1,825 vaccinated and 2,715 not vaccinated) in China to analyze this phenomenon empirically. The propensity score matching (PSM) model is employed to analyze the impact of vaccination against COVID-19 on participants' attitudes toward protective countermeasures. The findings showed that gender, age, education level, occupation risk, individual health risk perception, public health risk perception, social responsibility, peer effect, and government supervision are the main drivers for participants to be vaccinated with COVID-19's vaccines. The results further show that vaccination lessened participants' frequency of hand washing by 1.75 times and their compliance frequency intensity of observing physical distancing by 1.24 times. However, the rate of mask-wearing did not reduce significantly, implying that China's main countermeasure of effective mask-wearing effectively controls COVID-19. Moreover, the findings indicate that a reduction in the frequency of hand washing and observing physical distance could cause a resurgence of COVID-19. In conclusion, factors leading to the eradication of SARS-CoV-2 from the world are complex to be achieved, so the exploration of COVID-19 vaccination and people's attitude toward protective countermeasures may provide insights for policymakers to encourage vaccinated people to follow protective health measures and help in completely defeating the COVID-19 from the globe.

Safety of COVID-19 vaccines

This study is aimed to identify the adverse effects associated with three types of coronavirus disease 2019 vaccines. Approximately 1736 individuals agreed to participate in this study. The participants involved in the study were individuals who had received the first dose or full course (two doses) of the vaccine at least 30 days before the survey. A direct and interactive web‐based system interview with a paper and electronic version of the questionnaire was used for all participants. A total of 1736 randomized individuals were identified. The reactogenicity of the vaccines including pain, redness, urticaria, and swelling at the site of the injection was reported in 34.56% of the participants. Local site reaction was reported in more individuals who had Pfizer and AstraZeneca vaccines than those who received the Sinopharm vaccine. The systemic events were more common with AstraZeneca and Pfizer vaccines, symptoms reported were fatigue, body pain, headache, muscle pain, fever, and gastrointestinal side effects. There were no correlations between age or gender, and the duration of the adverse effects for the three vaccines. Swelling and severe allergic reaction of the eyelids, severe hypotension, generalized body aches, shortness of breath, weakness and numbness on the injected arm, acute hyperglycemia, severe chest pain, and fever more than 39°C were among the unusual signs and symptoms reported by the participants. Pfizer, AstraZeneca, and Sinopharm vaccines were found to be safe and Sinopharm vaccine showed a lower prevalence of adverse effects compared with the other vaccines. The duration and severity of adverse effects were not affected by age or gender. Unusual side effects should be closely monitored to establish determine they are linked to the immunization.

Current vaccine technology with an emphasis on recombinant measles virus as a new perspective for vaccination against SARS-CoV-2

The novel coronavirus disease 2019 (COVID-19) that emerged in China has spread to more than 212 countries to date. COVID-19 can cause serious acute respiratory syndrome (SARS). Therefore, research advances on the associated SARS-coronavirus-2 (CoV-2) may enable the scientific community to establish effective vaccines to prevent SARS-CoV-2 infections by increasing understanding of viral pathogenesis. Measles virus (MV) expressing SARS-CoV-2 spike protein (S) represents a promising class of biotherapeutic agents to combat this virus. The potential of such recombinant viruses has been well recognized for the treatment of many diseases. We summarize and review herein a potential therapeutic intervention strategy against COVID-19 infection based on MVSchw2-SARS-S and MVSchw2-SARS-Ssol with the aim of assessing the suitability of recombinant MV as a potential new candidate SARS vaccine. Such analysis of COVID-19 pathogenesis could also help establish appropriate therapeutic targets for the production of specific antiviral agents against this newly emerged pathogen.

A comprehensive overview of vaccines developed for pandemic viral pathogens over the past two decades including those in clinical trials for the current novel SARS-CoV-2

The unprecedented coronavirus disease 2019 (COVID-19) is triggered by a novel strain of coronavirus namely, Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2). Researchers are working around the clock to control this pandemic and consequent waves of viral reproduction, through repurposing existing drugs as well as designing new vaccines. Several countries have hastened vaccine design and clinical trials to quickly address this outbreak. Currently, more than 250 aspirants against SARS-CoV-2 are in progress, including mRNA-replicating or non-replicating viral vectored-, DNA-, autologous dendritic cell-based-, and inactivated virus-vaccines. Vaccines work by prompting effector mechanisms such as cells/molecules, which target quickly replicating pathogens and neutralize their toxic constituents. Vaccine-stimulated immune effectors include adjuvant, affinity, avidity, affinity maturation, antibodies, antigen-presenting cells, B lymphocytes, carrier protein, CD4+ T-helper cells. In this review, we describe updated information on the various vaccines available over the last two decades, along with recent progress in the ongoing battle developing 63 diverse vaccines against SARS-CoV-2. The inspiration of our effort is to convey the current investigation focus on registered clinical trials (as of January 08, 2021) that satisfy the safety and efficacy criteria of international wide vaccine development.

Using structural equation modeling to predict Indian people's attitudes and intentions towards COVID-19 vaccination

BACKGROUND AND AIM

Understanding people's attitudes towards Covid-19 vaccination is crucial to the successful implementation of a vaccination program. Hence this research study seeks to identify critical factors influencing Indian people's attitudes and intentions to take up Covid-19 vaccinations.

METHODS

An online questionnaire was administered to a sample (n = 254) drawn from Indian population, to assess the impact of perceived benefits, risk perceptions, social media exposure, social norms, and trust associated with Covid-19 vaccines on people's attitudes towards Covid-19 vaccines and their intentions to take up the Covid-19 vaccinations.

RESULTS

The findings showed that the perceived benefits, social norms, and trust correlated significantly with people's attitudes towards Covid-19 vaccinations. In contrast, risk perceptions and social media exposure showed an insignificant influence on people's attitudes towards Covid-19 vaccinations. Social norms, trust, and people's attitudes towards the Covid-19 vaccinations are significantly correlated with their intentions to take up Covid-19 vaccinations. On the contrary, social media exposure was found to have an insignificant influence on people's intentions to take up Covid-19 vaccinations.

CONCLUSION

Participants' intentions to take up Covid-19 vaccinations was influenced mainly by their attitudes and perceptions of Covid-19 vaccines in general, which strongly confirms the importance of various dimensions (perceived benefits, trust, social norms) of Covid-19 vaccines in cultivating Covid-19 vaccination acceptance among participants'.