Current advances in the development of SARS-CoV-2 vaccines

Efficacy and limitations of SARS-CoV-2 vaccines - A systematic review

The emergence of the SARS-CoV-2 virus worldwide led to the call for the development of effective and safe vaccines to contain the spread and effects of COVID-19. Using information from 40 publications, including clinical trials and observational studies from 2019 to 2024, this review assesses the effectiveness, safety, and limitations of four major vaccines: Sinopharm (BBIBP-CorV), Moderna (mRNA-1273), Pfizer-BioNTech (BNT162b2), and CoronaVac. Pfizer-BioNTech and Moderna's mRNA vaccines proved to be more effective than others; Moderna's vaccines showed an efficacy of 94.1 % against symptomatic infection, while Pfizer-BioNTech's vaccines showed an efficacy of up to 95 %, against severe diseases and hospitalization. These vaccinations, which included protection against Omicron and Delta variants, offered notable protection against serious illness, hospitalization, and mortality. Severe adverse events were rare while most adverse events were mild to moderate, such as headaches, fatigue, and localized reactions. In contrast, inactivated virus vaccines such as Sinopharm and CoronaVac with efficacies ranging from 50 to 79 % against symptomatic infection showed lower levels of effectiveness. In Phase 3 trial, Sinopharm showed 72.8 % efficacy, whereas CoronaVac demonstrated roughly 67 % efficacy in population against hospitalization and severe disease. Booster doses were required for adequate immunological response, especially against novel strains, as these vaccinations proved to be less effective in older populations. They showed considerable safety profiles, with mild side effects, but their low immunogenicity is concerning. This review emphasizes the importance of continuously evaluating vaccines in response to the evolving virus, essential for improving international immunization programs.

Antibody-dependent enhancement of coronaviruses

The COVID-19 pandemic presents a significant challenge to the global health and the world economy, with humanity engaged in an extended struggle against the virus. Notable advancements have been achieved in the development of vaccines and therapeutic interventions, including the application of neutralizing antibodies (NAbs) and convalescent plasma (CP). While antibody-dependent enhancement (ADE) has not been observed in human clinical studies related to SARS-CoV-2, the potential for ADE remains a critical concern and challenge in addressing SARS-CoV-2 infections. Moreover, the causal relationship between ADE and viral characteristics remains to be clearly elucidated. Viruses that present with severe clinical manifestations of ADE have demonstrated the capacity to replicate in macrophages or other immune cells, or to alter the immunological status of these cells, which induces abortive infections characterized by systemic inflammation. In this review, we summarize experimental observations and clinical evidence concerning the ADE effect associated with coronaviruses. We critically examine the potential mechanisms through which coronaviruses mediate ADE, and propose strategies to mitigate this phenomenon in the context of viral infection treatment. Our aim is to offer informed recommendations for the containment of the COVID-19 pandemic and to strengthen the response to SARS-CoV-2, as well as to prepare for potential future coronavirus threats.

Immunobiology and immunotherapy of COVID-19

The SARS-CoV-2 outbreak in late 2019 triggered a major increase in activities related to immunobiology and immunotherapy to cope with and find solutions to end the COVID-19 pandemic. The unprecedented approach to research and development of drugs and vaccines against SARS-CoV-2 has substantially improved the understanding of immunobiology for COVID-19, which can also be applied to other infectious diseases. Major efforts were dedicated to the repurposing of existing antiviral drugs and the development of novel ones. For this reason, numerous approaches to evaluating interferons, immunoglobulins, and cytokine inhibitors have been conducted. Antibody-based therapies, especially employing monoclonal antibodies have also been on the agenda. Cell-based therapies involving dendritic cells, macrophages, and CAR T-cell approaches have been evaluated. Many existing antiviral drugs have been repurposed for COVID-19 and novel formulations have been tested. The extraordinarily rapid development of efficient vaccines led to the breakthrough of novel vaccine approaches such as mRNA-based vaccines saving millions of lives. Waning immunity of existing vaccines and emerging SARS-CoV-2 variants have required additional booster vaccinations and re-engineering of new versions of COVID-19 vaccines.

Current Advances in Viral Nanoparticles for Biomedicine

Viral nanoparticles (VNPs) have emerged as crucial tools in the field of biomedicine. Leveraging their biological and physicochemical properties, VNPs exhibit significant advantages in the prevention, diagnosis, and treatment of human diseases. Through techniques such as chemical bioconjugation, infusion, genetic engineering, and encapsulation, these VNPs have been endowed with multifunctional capabilities, including the display of functional peptides or proteins, encapsulation of therapeutic drugs or inorganic particles, integration with imaging agents, and conjugation with bioactive molecules. This review provides an in-depth analysis of VNPs in biomedicine, elucidating their diverse types, distinctive features, production methods, and complex design principles behind multifunctional VNPs. It highlights recent innovative research and various applications, covering their roles in imaging, drug delivery, therapeutics, gene delivery, vaccines, immunotherapy, and tissue regeneration. Additionally, the review provides an assessment of their safety and biocompatibility and discusses challenges and future opportunities in the field, underscoring the vast potential and evolving nature of VNP research.

[Evaluation of the effectiveness of chemical inactivation and immunogenicity of the Omicron variant of the SARS-CoV-2 virus]

INTRODUCTION

The rapid spread of coronavirus infection COVID-19 among the population of many countries around the world has contributed to the emergence of many genetic variants of SARS-CoV-2. Compared to previous coronavirus variants, the new Omicron variants have shown a noticeable degree of mutation. Virus inactivation is one of the most important steps in the development of inactivated vaccines. The chemical inactivation agents currently used are β-propiolactone and formaldehyde, but there is no uniform standard for designing and specifying the inactivation process.

OBJECTIVE

Evaluation and comparison of the effectiveness of chemical inactivation of two agents, formaldehyde and β-propiolactone against immunogenicity of the Omicron variant of the SARS-CoV-2 virus.

MATERIALS AND METHODS

Nasopharyngeal swabs were used to obtain the SARS-CoV-2 Omicron variant virus. Vero cell culture was used to isolate, reproduce, titrate the virus, and perform a neutralization reaction. The kinetics of studying the inactivation of the virus by chemical agents such as formaldehyde and β-propiolactone was carried out.

RESULTS

Studies have been conducted to comparatively evaluate the effectiveness of chemical agents used to inactivate the SARS-CoV-2 virus of the Omicron variant, planned for use in the production of an inactivated whole-virion vaccine. Formaldehyde and β-propiolactone were used as inactivation agents in concentrations of 0.05, 0.1, 0.5% of the total volume of the virus suspension. It has been established that complete inactivation of the virus by formaldehyde in the concentrations used at a temperature of 37 °C occurs within up to 2 hours, and when using beta-propiolactone, within up to 12 hours.

CONCLUSION

Inactivated virus samples have different antigenic activity depending on the concentration of the inactivation agents used. The most pronounced antigenic activity is manifested in samples of the pathogen that were treated with an inactivation agent at a mild concentration of 0.05%. Increasing the concentration of inactivation agent by 5 or more times leads to a significant decrease in the antigenicity of the SARS-CoV-2 virus. With the inactivation modes used, the loss of biological activity of the virus occurs faster and antigenicity is retained largely when treated with formaldehyde.

Development and validation of a prognostic model for colon cancer based on mitotic gene signatures and immune microenvironment analysis

BACKGROUND

Mitotic processes play a pivotal role in tumor progression and immune responses. However, the correlation between mitosis-related genes, clinical outcomes, and the tumor microenvironment (TME) in colon cancer remains unclear. This study aims to develop a prognostic and therapeutic significance model for colon cancer based on mitosis-related genes.

METHODS

RNA expression profiles and clinical data of 453 colon cancer patients were downloaded from The Cancer Genome Atlas (TCGA). Mitosis-related genes were selected from the MsigDb database. The gene model was constructed using differential analysis, univariate and multivariate Cox regression, and Lasso regression analyses. The predictive model was validated using data from the GSE17536, GSE17537, and GSE39582 datasets. Predictive accuracy was evaluated via Receiver Operating Characteristic (ROC) curves, while nomograms were developed by integrating clinical and pathological features. Gene set enrichment analysis explored biological processes and pathways linked to the model. TME was assessed using ESTIMATE, and the proportion and function of immune cells were analyzed through CIBERSORT. Drug sensitivity analysis was conducted using the CTRP database.

RESULTS

A predictive model based on 17 mitosis-related genes (KIFC1, CCNF, EME1, CDC25C, ORC1, CCNJL, ANKRD53, MEIS2, FZD3, TPD52L1, MAPK3, CDKN2A, EDN3, NPM2, PSRC1, INHBA, BIRC5) was created. The model exhibited robust predictive performance across both training and validation cohorts. Nomograms for predicting 3-, 5-, and 7-year survival rates in colon cancer (COAD) patients were generated. The model's correlation with immune cell infiltration and function was highlighted.

CONCLUSION

The mitosis-related gene model serves as a valuable indicator for predicting survival outcomes in colon cancer patients.

Development of an ancestral DC and TLR4-inducing multi-epitope peptide vaccine against the spike protein of SARS-CoV and SARS-CoV-2 using the advanced immunoinformatics approaches

The oldest human coronavirus that started pandemics is severe acute respiratory syndrome virus (SARS-CoV). While SARS-CoV was eradicated, its new version, SARS-CoV2, caused the global pandemic of COVID-19. Evidence highlights the harmful events orchestrated by these viruses are mediated by Spike (S)P protein. Experimental epitopes of the S protein which were overlapping and ancestral between SARS-CoV and SARS-CoV-2 were obtained from the immune epitopes database (IEDB). The epitopes were then assembled in combination with a 50 S ribosomal protein L7/L12 adjuvant, a Mycobacterium tuberculosis-derived element and mediator of dendritic cells (DCs) and toll-like receptor 4 (TLR4). The immunogenic sequence was modeled by the GalaxyWeb server. After the improvement and validation of the protein structure, the physico-chemical properties and immune simulation were performed. To investigate the interaction with TLR3/4, Molecular Dynamics Simulation (MDS) was used. By merging the 17 B- and T-lymphocyte (HTL/CTL) epitopes, the vaccine sequence was created. Also, the Ramachandran plot presented that most of the residues were located in the most favorable and allowed areas. Moreover, SnapGene was successful in cloning the DNA sequence linked to our vaccine in the intended plasmid. A sequence was inserted between the XhoI and SacI position of the pET-28a (+) vector, and simulating the agarose gel revealed the existence of the inserted gene in the cloned plasmid with SARS vaccine (SARSV) construct, which has a 6565 bp in length overall. In terms of cytokines/IgG response, immunological simulation revealed a strong immune response. The stabilized vaccine showed strong interactions with TLR3/4, according to Molecular Dynamics Simulation (MDS) analysis. The present ancestral vaccine targets common sequences which seem to be valuable targets even for the new variant SARS-CoV-2.

Exploring the underlying molecular mechanisms of acute myocardial infarction after SARS-CoV-2 infection

An increase in acute myocardial infarction (AMI)-related deaths has been reported during the COVID-19 pandemic. Despite evidence suggesting the association between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and AMI, the underlying mechanisms remain unclear. Here, we integrated mRNA and microRNA expression profiles related to SARS-CoV-2 infection and AMI from public databases. We then performed transcriptomic analysis using bioinformatics and systems biology approaches to explore the potential molecular mechanisms of SARS-CoV-2 infection affects AMI. First, twenty-one common differentially expressed genes (DEGs) were identified from SARS-CoV-2 infection and AMI patients in endothelial cells datasets and then we performed functional analysis to predict the roles of these DEGs. The functional analysis emphasized that the endothelial cell response to cytokine stimulus due to excessive inflammation was essential in these two diseases. Importantly, the tumor necrosis factor and interleukin-17 signaling pathways appeared to be integral factors in this mechanism. Interestingly, most of these common genes were also upregulated in transcriptomic datasets of SARS-CoV-2-infected cardiomyocytes, suggesting that these genes may be shared in cardiac- and vascular-related injuries. We subsequently built a protein-protein interaction network and extracted hub genes and essential modules from this network. At the transcriptional and post-transcriptional levels, regulatory networks with common DEGs were also constructed, and some key regulator signatures were further identified and validated. In summary, our research revealed that a highly activated inflammatory response in patients with COVID-19 might be a crucial factor for susceptibility to AMI and we identified some candidate genes and regulators that could be used as biomarkers or potential therapeutic targets.

A live attenuated influenza B virus vaccine expressing RBD elicits protective immunity against SARS-CoV-2 in mice

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a significant threat to human health globally. It is crucial to develop a vaccine to reduce the effect of the virus on public health, economy, and society and regulate the transmission of SARS-CoV-2. Influenza B virus (IBV) can be used as a vector that does not rely on the current circulating influenza A strains. In this study, we constructed an IBV-based vector vaccine by inserting a receptor-binding domain (RBD) into a non-structural protein 1 (NS1)-truncated gene (rIBV-NS110-RBD). Subsequently, we assessed its safety, immunogenicity, and protective efficacy against SARS-CoV-2 in mice, and observed that it was safe in a mouse model. Intranasal administration of a recombinant rIBV-NS110-RBD vaccine induced high levels of SARS-CoV-2-specific IgA and IgG antibodies and T cell-mediated immunity in mice. Administering two doses of the intranasal rIBV-NS110-RBD vaccine significantly reduced the viral load and lung damage in mice. This novel IBV-based vaccine offers a novel approach for controlling the SARS-CoV-2 pandemic.

Immune responses during COVID-19 breakthrough cases in vaccinated children and adolescents

Background

Vaccine effectiveness against SARS-CoV-2 infection has been somewhat limited due to the widespread dissemination of the Omicron variant, its subvariants, and the immune response dynamics of the naturally infected with the virus.

Methods

Twelve subjects between 3-17 years old (yo), vaccinated with two doses of CoronaVac®, were followed and diagnosed as breakthrough cases starting 14 days after receiving the second dose. Total IgGs against different SARS-CoV-2 proteins and the neutralizing capacity of these antibodies after infection were measured in plasma. The activation of CD4+ and CD8+ T cells was evaluated in peripheral blood mononuclear cells stimulated with peptides derived from the proteins from the wild-type (WT) virus and Omicron subvariants by flow cytometry, as well as different cytokines secretion by a Multiplex assay.

Results

2 to 8 weeks post-infection, compared to 4 weeks after 2nd dose of vaccine, there was a 146.5-fold increase in neutralizing antibody titers against Omicron and a 38.7-fold increase against WT SARS-CoV-2. Subjects showed an increase in total IgG levels against the S1, N, M, and NSP8 proteins of the WT virus. Activated CD4+ T cells showed a significant increase in response to the BA.2 subvariant (p<0.001). Finally, the secretion of IL-2 and IFN-γ cytokines showed a discreet decrease trend after infection in some subjects.

Conclusion

SARS-CoV-2 infection in the pediatric population vaccinated with an inactivated SARS-CoV-2 vaccine produced an increase in neutralizing antibodies against Omicron and increased specific IgG antibodies for different SARS-CoV-2 proteins. CD4+ T cell activation was also increased, suggesting a conserved cellular response against the Omicron subvariants, whereas Th1-type cytokine secretion tended to decrease.

Clinical Trial Registration

clinicaltrials.gov #NCT04992260.

Autoimmune response after SARS-CoV-2 infection and SARS-CoV-2 vaccines

The complicated relationships between autoimmunity, COVID-19, and COVID-19 vaccinations are described, giving insight into their intricacies. Antinuclear antibodies (ANA), anti-Ro/SSA, rheumatoid factor, lupus anticoagulant, and antibodies against interferon (IFN)-I have all been consistently found in COVID-19 patients, indicating a high prevalence of autoimmune reactions following viral exposure. Furthermore, the discovery of human proteins with structural similarities to SARS-CoV-2 peptides as possible autoantigens highlights the complex interplay between the virus and the immune system in initiating autoimmunity. An updated summary of the current status of COVID-19 vaccines is presented. We present probable pathways underpinning the genesis of COVID-19 autoimmunity, such as bystander activation caused by hyperinflammatory conditions, viral persistence, and the creation of neutrophil extracellular traps. These pathways provide important insights into the development of autoimmune-related symptoms ranging from organ-specific to systemic autoimmune and inflammatory illnesses, demonstrating the wide influence of COVID-19 on the immune system.

The E3 ligase TRIM22 restricts SARS-CoV-2 replication by promoting proteasomal degradation of NSP8

Replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome is mediated by a complex of non-structural proteins (NSPs), of which NSP7 and NSP8 serve as subunits and play a key role in promoting the activity of RNA-dependent RNA polymerase (RdRp) of NSP12. However, the stability of subunits of the RdRp complex has rarely been reported. Here, we found that NSP8 was degraded by the proteasome in host cells, and identified tripartite motif containing 22 (TRIM22) as its E3 ligase. The interferon (IFN) signaling pathway was activated upon viral invasion into host cells, and TRIM22 expression increased. TRIM22 interacted with NSP8 and ubiquitinated it at Lys97 via K48-type ubiquitination. TRIM22 overexpression significantly reduced viral RNA and protein levels. Knockdown of TRIM22 enhanced viral replication. This study provides a new explanation for treating patients suffering from SARS-CoV-2 with IFNs and new possibilities for drug development targeting the interaction between NSP8 and TRIM22.IMPORTANCENon-structural proteins (NSPs) play a crucial role in the replication of severe acute respiratory syndrome coronavirus 2, facilitating virus amplification and propagation. In this study, we conducted a comprehensive investigation into the stability of all subunits comprising the RNA-dependent RNA polymerase complex. Notably, our results reveal for the first time that NSP8 is a relatively unstable protein, which is found to be readily recognized and degraded by the proteasome. This degradation process is mediated by the host E3 ligase tripartite motif containing 22 (TRIM22), which is also a member of the interferon stimulated gene (ISG) family. Our study elucidates a novel mechanism of antiviral effect of TRIM22, which utilizes its own E3 ubiquitin ligase activity to hinder viral replication by inducing ubiquitination and subsequent degradation of NSP8. These findings provide new ideas for the development of novel therapeutic strategies. In addition, the conserved property of NSP8 raises the possibility of developing broad antiviral drugs targeting the TRIM22-NSP8 interaction.

COVID-19 Vaccines: Where Did We Stand at the End of 2023?

Vaccine development against SARS-CoV-2 has been highly successful in slowing down the COVID-19 pandemic. A wide spectrum of approaches including vaccines based on whole viruses, protein subunits and peptides, viral vectors, and nucleic acids has been developed in parallel. For all types of COVID-19 vaccines, good safety and efficacy have been obtained in both preclinical animal studies and in clinical trials in humans. Moreover, emergency use authorization has been granted for the major types of COVID-19 vaccines. Although high safety has been demonstrated, rare cases of severe adverse events have been detected after global mass vaccinations. Emerging SARS-CoV-2 variants possessing enhanced infectivity have affected vaccine protection efficacy requiring re-design and re-engineering of novel COVID-19 vaccine candidates. Furthermore, insight is given into preparedness against emerging SARS-CoV-2 variants.

A Comparison of the Effects of Chlorhexidine and Sodium Bicarbonate Mouthwashes on COVID-19-Related Symptoms

BACKGROUND

Some studies have reported that mouthwashes can decrease the viral load in the mouth, but there is not much information about the effectiveness of mouthwashes on coronavirus disease 2019 (COVID-19). This study was conducted to compare the impact of using two types of mouthwash, chlorhexidine and sodium bicarbonate, on COVID-19 symptoms and infection.

MATERIALS AND METHODS

The present three-group, double-blind clinical trial examined 116 operating room nurses and anesthesia personnel of certain hospitals of Isfahan University of Medical Sciences, Isfahan, Iran. The participants were randomly assigned to three groups: intervention group 1 (chlorhexidine mouthwash), intervention group 2 (sodium bicarbonate mouthwash), and the control group (placebo). Mouthwash was used twice a day (morning and night) for 2 weeks. The participants were monitored in terms of COVID-19-related symptoms for 4 weeks, from the first day of mouthwash use.

RESULTS

Fisher's exact test indicated a significant difference between the chlorhexidine and control groups in terms of the onset of COVID-19-related symptoms (p = 0.02). There was no significant difference in the symptoms of COVID-19 between the groups, but the groups were significantly different in terms of all symptoms at a 4-week interval (p = 0.04). Furthermore, headache was less observed in the chlorhexidine (p = 0.007) and sodium bicarbonate (p = 0.03) groups compared to the control group.

CONCLUSIONS

The use of 0.2% chlorhexidine mouthwash can decrease the onset of COVID-19-related symptoms in health-care workers. In addition, this mouthwash can partially reduce the symptoms of this disease in comparison to the control and sodium bicarbonate groups.

Rapidly Evolving SARS-CoV-2: A Brief Review Regarding the Variants and their Effects on Vaccine Efficacies

Since the commencement of Corona Virus Disease 2019 (COVID-19) pandemic, which has resulted in millions of mortalities globally, the efforts to minimize the damages have equally been up to the task. One of those efforts includes the mass vaccine development initiative targeting the deadly Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). So far, vaccines have tremendously decreased the rate of transmission and infection in most parts of the world. However, the repeated resurgence of different types of mutated versions of the virus, also known as variants, has somehow created uncertainties about the efficacies of different types of vaccines. This review discusses some of the interesting SARS-CoV-2 features, including general structure, genomics, and mechanisms of variants development and their consequent immune escape. This review also focuses very briefly on antigenic drift, shift, and vaccine-developing platforms.

Willingness of college students to receive COVID-19 heterologous vaccination in Taizhou, China

This study aimed to determine the willingness of college students to choose COVID-19 heterologous vaccination and its associated influencing factors in Taizhou, China. A population-based, self-administered online questionnaire was conducted from March 15 to 17, 2022. Of the 2,463 participants who had received the invitation, 1,821 responded to the survey (response rate = 73.9%). Only 14% (86/614) of those willing to receive a booster would chose a heterologous vaccination; the perception of better effectiveness of a COVID-19 heterologous vaccination booster was the significant factor (X2 = 22.671, p < .001). Additionally, female college students'older age (χ2 = 7.523, P = .023), major of medical (χ2 = 6.294, P = .012), and better perceived effectiveness of COVID-19 heterologous vaccination booster (χ2 = 22.659, P < .001), were more willing to receive heterologous booster doses. Chinese college students have a strong willingness to receive booster shots, but the percentage of those willing to receive a heterologous vaccine is only 14.0%, and the lack of understanding of its effectiveness is an important factor in the low proportion of heterologous vaccine selection. Health education, public health awareness, and the disclosure of heterologous vaccine information can help improve the public's understanding of heterologous vaccines and provide them with more choices.

Immunogenicity of mucosal COVID-19 vaccine candidates based on the highly attenuated vesicular stomatitis virus vector (VSVMT) in golden syrian hamster

COVID-19 is caused by coronavirus SARS-CoV-2. Current systemic vaccines generally provide limited protection against viral replication and shedding within the airway. Recombinant VSV (rVSV) is an effective vector which inducing potent and comprehensive immunities. Currently, there are two clinical trials investigating COVID-19 vaccines based on VSV vectors. These vaccines were developed with spike protein of WA1 which administrated intramuscularly. Although intranasal route is ideal for activating mucosal immunity with VSV vector, safety is of concern. Thus, a highly attenuated rVSV with three amino acids mutations in matrix protein (VSVMT) was developed to construct safe mucosal vaccines against multiple SARS-CoV-2 variants of concern. It demonstrated that spike protein mutant lacking 21 amino acids in its cytoplasmic domain could rescue rVSV efficiently. VSVMT indicated improved safeness compared with wild-type VSV as the vector encoding SARS-CoV-2 spike protein. With a single-dosed intranasal inoculation of rVSVΔGMT-SΔ21, potent SARS-CoV-2 specific neutralization antibodies could be stimulated in animals, particularly in term of mucosal and cellular immunity. Strikingly, the chimeric VSV encoding SΔ21 of Delta-variant can induce more potent immune responses compared with those encoding SΔ21 of Omicron- or WA1-strain. VSVMT is a promising platform to develop a mucosal vaccine for countering COVID-19.

A novel recombinant S-based subunit vaccine induces protective immunity against porcine deltacoronavirus challenge in piglets

IMPORTANCE

As an emerging porcine enteropathogenic coronavirus that has the potential to infect humans, porcine deltacoronavirus (PDCoV) is receiving increasing attention. However, no effective commercially available vaccines against this virus are available. In this work, we designed a spike (S) protein and receptor-binding domain (RBD) trimer as a candidate PDCoV subunit vaccine. We demonstrated that S protein induced more robust humoral and cellular immune responses than the RBD trimer in mice. Furthermore, the protective efficacy of the S protein was compared with that of inactivated PDCoV vaccines in piglets and sows. Of note, the immunized piglets and suckling pig showed a high level of NAbs and were associated with reduced virus shedding and mild diarrhea, and the high level of NAbs was maintained for at least 4 months. Importantly, we demonstrated that S protein-based subunit vaccines conferred significant protection against PDCoV infection.

Type III interferon exerts thymic stromal lymphopoietin in mediating adaptive antiviral immune response

Previously, it was believed that type III interferon (IFN-III) has functions similar to those of type I interferon (IFN-I). However, recently, emerging findings have increasingly indicated the non-redundant role of IFN-III in innate antiviral immune responses. Still, the regulatory activity of IFN-III in adaptive immune response has not been clearly reported yet due to the low expression of IFN-III receptors on most immune cells. In the present study, we reviewed the adjuvant, antiviral, antitumor, and disease-moderating activities of IFN-III in adaptive immunity; moreover, we further elucidated the mechanisms of IFN-III in mediating the adaptive antiviral immune response in a thymic stromal lymphopoietin (TSLP)-dependent manner, a pleiotropic cytokine involved in mucosal adaptive immunity. Research has shown that IFN-III can enhance the antiviral immunogenic response in mouse species by activating germinal center B (GC B) cell responses after stimulating TSLP production by microfold (M) cells, while in human species, TSLP exerts OX40L for regulating GC B cell immune responses, which may also depend on IFN-III. In conclusion, our review highlights the unique role of the IFN-III/TSLP axis in mediating host adaptive immunity, which is mechanically different from IFN-I. Therefore, the IFN-III/TSLP axis may provide novel insights for clinical immunotherapy.

A study on the effect of natural products against the transmission of B.1.1.529 Omicron

BACKGROUND

The recent outbreak of the Coronavirus pandemic resulted in a successful vaccination program launched by the World Health Organization. However, a large population is still unvaccinated, leading to the emergence of mutated strains like alpha, beta, delta, and B.1.1.529 (Omicron). Recent reports from the World Health Organization raised concerns about the Omicron variant, which emerged in South Africa during a surge in COVID-19 cases in November 2021. Vaccines are not proven completely effective or safe against Omicron, leading to clinical trials for combating infection by the mutated virus. The absence of suitable pharmaceuticals has led scientists and clinicians to search for alternative and supplementary therapies, including dietary patterns, to reduce the effect of mutated strains.

MAIN BODY

This review analyzed Coronavirus aetiology, epidemiology, and natural products for combating Omicron. Although the literature search did not include keywords related to in silico or computational research, in silico investigations were emphasized in this study. Molecular docking was implemented to compare the interaction between natural products and Chloroquine with the ACE2 receptor protein amino acid residues of Omicron. The global Omicron infection proceeding SARS-CoV-2 vaccination was also elucidated. The docking results suggest that DGCG may bind to the ACE2 receptor three times more effectively than standard chloroquine.

CONCLUSION

The emergence of the Omicron variant has highlighted the need for alternative therapies to reduce the impact of mutated strains. The current review suggests that natural products such as DGCG may be effective in binding to the ACE2 receptor and combating the Omicron variant, however, further research is required to validate the results of this study and explore the potential of natural products to mitigate COVID-19.

ESKAPE bacteria characterization reveals the presence of Acinetobacter baumannii and Pseudomonas aeruginosa outbreaks in COVID-19/VAP patients

INTRODUCTION

A decrease of detection of outbreaks by multidrug-resistant bacteria in critical areas has been reduced due to COVID-19 pandemic. Therefore, molecular epidemiological surveillance should be a primary tool to reveal associations not evident by classical epidemiology. The aim of this work was to demonstrate the presence of hidden outbreaks in the first wave of the COVID-19 pandemic and to associate their possible origin.

METHODS

A population of 96 COVID-19 patients was included in the study (April to June 2020) from Hospital Juárez de México. Genetic identification and antimicrobial susceptibility testing of VAP causative agents isolated from COVID-19 patients was performed. Resistance phenotypes were confirmed by PCR. Clonal association of isolates was performed by analysis of intergenic regions obtained. Finally, the association of clonal cases of VAP patients was performed by timelines.

RESULTS

ESKAPE and non-ESKAPE bacteria were identified as causative agents of VAP. ESKAPE bacteria were classified as MDR and XDR. Only A. baumannii and P. aeruginosa were identified as clonally distributed in 13 COVID-19/VAP patients. Time analysis showed that cross-transmission existed between patients and care areas.

CONCLUSIONS

Acinetobacter baumannii and Pseudomonas aeruginosa were involved in outbreaks non-detected in COVID-19/VAP patients in the first wave of COVID-19 pandemic.

The acceptance and hesitancy of COVID-19 vaccination among chronic obstructive pulmonary disease (COPD) patients

Severe acute respiratory syndrome coronavirus 2, which is responsible for the coronavirus disease 2019 (COVID-19), causes severe clinical outcomes in old individuals and patients with underlying diseases, including chronic obstructive pulmonary disease (COPD). Considering vaccination is still the most effective method to prevent COVID-19-associated death, it is imperative to evaluate COPD patients' attitudes toward the COVID-19 vaccine. This cross-sectional design study was conducted to assess vaccine acceptance and hesitancy among 212 COPD patients who attended the outpatient department from January 1, 2021, to July 31, 2022. All of the patients were not vaccinated and had undertaken lung function test at the time of our survey. Of 212 participants, 164 (77.4%) were willing to be vaccinated immediately while 48 (22.6%) were hesitant to be vaccinated. Compared with the acceptance group, patients who did not accept the vaccination instantly tended to have more comorbidities, like hypertension, coronary heart disease, recent cancers, and higher Modified British Medical Research Council score, or more frequent acute exacerbation. For the patients willing to be vaccinated, the main factors motivating them were an authorities-endorsed vaccine, free vaccination, and no obvious adverse reactions. For the hesitant group, no recommendation from the treating physician was the biggest obstacle for them to accept vaccination. Our results provide useful guidance for making intervention measures to enhance COPD patients' acceptance of a new COVID-19 vaccine. For those patients with comorbidities, treating physicians promoting messages framing the safety of vaccination is necessary to increase immunization rates.

Efficacy of Vaccine Protection Against COVID-19 Virus Infection in Patients with Chronic Liver Diseases

The outbreak of coronavirus disease 2019 (COVID-19) has resulted in significant morbidity and mortality worldwide. Vaccination against coronavirus disease 2019 is a useful weapon to combat the virus. Patients with chronic liver diseases (CLDs), including compensated or decompensated liver cirrhosis and noncirrhotic diseases, have a decreased immunologic response to coronavirus disease 2019 vaccines. At the same time, they have increased mortality if infected. Current data show a reduction in mortality when patients with chronic liver diseases are vaccinated. A suboptimal vaccine response has been observed in liver transplant recipients, especially those receiving immunosuppressive therapy, so an early booster dose is recommended to achieve a better protective effect. Currently, there are no clinical data comparing the protective efficacy of different vaccines in patients with chronic liver diseases. Patient preference, availability of the vaccine in the country or area, and adverse effect profiles are factors to consider when choosing a vaccine. There have been reports of immune-mediated hepatitis after coronavirus disease 2019 vaccination, and clinicians should be aware of that potential side effect. Most patients who developed hepatitis after vaccination responded well to treatment with prednisolone, but an alternative type of vaccine should be considered for subsequent booster doses. Further prospective studies are required to investigate the duration of immunity and protection against different viral variants in patients with chronic liver diseases or liver transplant recipients, as well as the effect of heterologous vaccination.

Intramuscular administration of recombinant Newcastle disease virus expressing SARS-CoV-2 spike protein protects hACE-2 TG mice against SARS-CoV-2 infection

Coronavirus disease 2019 (Covid-19) caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) became a pandemic, causing significant burden on public health worldwide. Although the timely development and production of mRNA and adenoviral vector vaccines against SARS-CoV-2 have been successful, issues still exist in vaccine platforms for wide use and production. With the potential for proliferative capability and heat stability, the Newcastle disease virus (NDV)-vectored vaccine is a highly economical and conceivable candidate for treating emerging diseases. In this study, a recombinant NDV-vectored vaccine expressing the spike (S) protein of SARS-CoV-2, rK148/beta-S, was developed and evaluated for its efficacy against SARS-CoV-2 in K18-hACE-2 transgenic mice. Intramuscular vaccination with low dose (10^6.0 EID₅₀) conferred a survival rate of 76 % after lethal challenge of a SARS-CoV-2 beta (B.1.351) variant. When administered with a high dose (10^7.0 EID₅₀), vaccinated mice exhibited 100 % survival rate and reduced lung viral load against both beta and delta variants (B.1.617.2). Together with the protective immunity, rK148/beta-S is an accessible and cost-effective SARS-CoV-2 vaccine.

Structural and non-structural proteins in SARS-CoV-2: potential aspects to COVID-19 treatment or prevention of progression of related diseases

Coronavirus disease 2019 (COVID-19) is caused by a new member of the Coronaviridae family known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). There are structural and non-structural proteins (NSPs) in the genome of this virus. S, M, H, and E proteins are structural proteins, and NSPs include accessory and replicase proteins. The structural and NSP components of SARS-CoV-2 play an important role in its infectivity, and some of them may be important in the pathogenesis of chronic diseases, including cancer, coagulation disorders, neurodegenerative disorders, and cardiovascular diseases. The SARS-CoV-2 proteins interact with targets such as angiotensin-converting enzyme 2 (ACE2) receptor. In addition, SARS-CoV-2 can stimulate pathological intracellular signaling pathways by triggering transcription factor hypoxia-inducible factor-1 (HIF-1), neuropilin-1 (NRP-1), CD147, and Eph receptors, which play important roles in the progression of neurodegenerative diseases like Alzheimer's disease, epilepsy, and multiple sclerosis, and multiple cancers such as glioblastoma, lung malignancies, and leukemias. Several compounds such as polyphenols, doxazosin, baricitinib, and ruxolitinib could inhibit these interactions. It has been demonstrated that the SARS-CoV-2 spike protein has a stronger affinity for human ACE2 than the spike protein of SARS-CoV, leading the current study to hypothesize that the newly produced variant Omicron receptor-binding domain (RBD) binds to human ACE2 more strongly than the primary strain. SARS and Middle East respiratory syndrome (MERS) viruses against structural and NSPs have become resistant to previous vaccines. Therefore, the review of recent studies and the performance of current vaccines and their effects on COVID-19 and related diseases has become a vital need to deal with the current conditions. This review examines the potential role of these SARS-CoV-2 proteins in the initiation of chronic diseases, and it is anticipated that these proteins could serve as components of an effective vaccine or treatment for COVID-19 and related diseases. Video Abstract.

Immunodominant SARS-CoV-2-specific CD4+ and CD8+ T-cell responses elicited by inactivated vaccines in healthy adults

Safety profiles and humoral responses to inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines have been previously assessed, but cellular immune responses to inactivated SARS-CoV-2 vaccines remain understudied. Here, we report the comprehensive characteristics of SARS-CoV-2-specific CD4⁺ and CD8⁺ T-cell responses elicited by the BBIBP-CorV vaccine. A total of 295 healthy adults were recruited, and SARS-CoV-2-specific T-cell responses were detected after stimulation with overlapping peptide pools spanning the entire length of the envelope (E), membrane (M), nucleocapsid (N), and spike (S) proteins. Robust and durable CD4⁺ (p < 0.0001) and CD8⁺ (p < 0.0001) T-cell responses specific to SARS-CoV-2 were detected following the third vaccination, with an increase in specific CD8⁺ T-cells, compared to CD4⁺ T-cells. Cytokine profiles showed that interferon gamma and tumor necrosis factor-α were predominantly expressed with the negligible expression of interleukin (IL)-4 and IL-10, indicating a Th1- or Tc1-biased response. Compared to E and M proteins, N and S activated a higher proportion of specific T-cells with broader functions. The predominant frequency of the N antigen (49/89) was highest for CD4⁺ T-cell immunity. Furthermore, N_19-36 and N_391-408 were identified to contain dominant CD8⁺ and CD4⁺ T-cell epitopes, respectively. In addition, N_19-36 -specific CD8⁺ T-cells were mainly effector memory CD45RA cells, whereas N_391-408 -specific CD4⁺ T-cells were mainly effector memory cells. Therefore, this study reports comprehensive features of T-cell immunity induced by the inactivated SARS-CoV-2 vaccine BBIBP-CorV and proposes highly conserved candidate peptides which may be beneficial in vaccine optimization.

Evidence-based policies in public health to address COVID-19 vaccine hesitancy

A fundamental basis for effective health-related policymaking of any democratic nation should be open and transparent communication between a government and its citizens, including scientists and healthcare professionals, to foster a climate of trust, especially during the ongoing COVID-19 mass vaccination campaign. Since misinformation is a leading cause of vaccine hesitancy, open data sharing through an evidence-based approach may render the communication of health strategies developed by policymakers with the public more effective, allowing misinformation and claims that are not backed by scientific evidence to be tackled. In this narrative review, we debate possible causes of COVID-19 vaccine hesitancy and links to the COVID-19 misinformation epidemic. We also put forward plausible solutions as recommended in the literature.

From Immunogen to COVID-19 vaccines: Prospects for the post-pandemic era

The COVID-19 pandemic has affected millions of people and posed an unprecedented burden on healthcare systems and economies worldwide since the outbreak of the COVID-19. A considerable number of nations have investigated COVID-19 and proposed a series of prevention and treatment strategies thus far. The pandemic prevention strategies implemented in China have suggested that the spread of COVID-19 can be effectively reduced by restricting large-scale gathering, developing community-scale nucleic acid testing, and conducting epidemiological investigations, whereas sporadic cases have always been identified in numerous places. Currently, there is still no decisive therapy for COVID-19 or related complications. The development of COVID-19 vaccines has raised the hope for mitigating this pandemic based on the intercross immunity induced by COVID-19. Thus far, several types of COVID-19 vaccines have been developed and released to into financial markets. From the perspective of vaccine use in globe, COVID-19 vaccines are beneficial to mitigate the pandemic, whereas the relative adverse events have been reported progressively. This is a review about the development, challenges and prospects of COVID-19 vaccines, and it can provide more insights into all aspects of the vaccines.

COVID-19 and hepatic injury: cellular and molecular mechanisms in diverse liver cells

The coronavirus disease 2019 (COVID-19) represents a global health and economic challenge. Hepatic injuries have been approved to be associated with severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection. The viral tropism pattern of SARS-CoV-2 can induce hepatic injuries either by itself or by worsening the conditions of patients with hepatic diseases. Besides, other factors have been reported to play a crucial role in the pathological forms of hepatic injuries induced by SARS-CoV-2, including cytokine storm, hypoxia, endothelial cells, and even some treatments for COVID-19. On the other hand, several groups of people could be at risk of hepatic COVID-19 complications, such as pregnant women and neonates. The present review outlines and discusses the interplay between SARS-CoV-2 infection and hepatic injury, hepatic illness comorbidity, and risk factors. Besides, it is focused on the vaccination process and the role of developed vaccines in preventing hepatic injuries due to SARS-CoV-2 infection.

A novel heterologous receptor-binding domain dodecamer universal mRNA vaccine against SARS-CoV-2 variants

There are currently approximately 4,000 mutations in the SARS-CoV-2 S protein gene and emerging SARS-CoV-2 variants continue to spread rapidly worldwide. Universal vaccines with high efficacy and safety urgently need to be developed to prevent SARS-CoV-2 variants pandemic. Here, we described a novel self-assembling universal mRNA vaccine containing a heterologous receptor-binding domain (HRBD)-based dodecamer (HRBDdodecamer) against SARS-CoV-2 variants, including Alpha (B.1.1.7), Beta (B.1.351), Gamma (B.1.1.28.1), Delta (B.1.617.2) and Omicron (B.1.1.529). HRBD containing four heterologous RBD (Delta, Beta, Gamma, and Wild-type) can form a stable dodecameric conformation under T4 trimerization tag (Flodon, FD). The HRBDdodecamer -encoding mRNA was then encapsulated into the newly-constructed LNPs consisting of a novel ionizable lipid (4N4T). The obtained universal mRNA vaccine (4N4T-HRBDdodecamer) presented higher efficiency in mRNA transfection and expression than the approved ALC-0315 LNPs, initiating potent immune protection against the immune escape of SARS-CoV-2 caused by evolutionary mutation. These findings demonstrated the first evidence that structure-based antigen design and mRNA delivery carrier optimization may facilitate the development of effective universal mRNA vaccines to tackle SARS-CoV-2 variants pandemic.

The SARS-CoV-2 nucleocapsid protein: its role in the viral life cycle, structure and functions, and use as a potential target in the development of vaccines and diagnostics

Coronavirus disease 2019 (COVID-19) continues to take a heavy toll on personal health, healthcare systems, and economies around the globe. Scientists are expending tremendous effort to develop diagnostic technologies for detecting positive infections within the shortest possible time, and vaccines and drugs specifically for the prevention and treatment of COVID-19 disease. At the same time, emerging novel variants have raised serious concerns about vaccine efficacy. The SARS-CoV-2 nucleocapsid (N) protein plays an important role in the coronavirus life cycle, and participates in various vital activities after virus invasion. It has attracted a large amount of attention for vaccine and drug development. Here, we summarize the latest research of the N protein, including its role in the SARS-CoV-2 life cycle, structure and function, and post-translational modifications in addition to its involvement in liquid-liquid phase separation (LLPS) and use as a basis for the development of vaccines and diagnostic techniques.

The functional views on response of host rabbit post coronavirus vaccination via ACE2 PET

Molecular imaging can dynamically and quantitatively record the biochemical changes in a systemic view. In this research, SARS-CoV-2 pseudovirus was intramuscularly injected to simulate the vaccination with inactivated virus. New Zealand white rabbits were evaluated with ¹⁸F-FDG PET for inflammation and ⁶⁸Ga-cyc-DX600 PET for ACE2 fluctuation, which were performed before and at 3, 7 and 14 days post injection (d P.I.); furthermore, one rabbit was vaccinated with two cycles with interval of 14 days for a longer period evaluation. Different with the vaccination-induced inflammatory response that was random and individual, ACE2 regulation was systemic and organ-specific: the liver and spleen were of a moderate decrease post injection but rebound at 14 d P.I., while there were a downward trend in heart, testis and bone marrow; besides, similar pattern of ACE2 regulation were recorded after the second injection with a relatively greater volatility. In conclusion, ACE2 PET gave a more comprehensive view on host response post vaccination, hold substantial promise in continuous monitoring of coronavirus vaccine administration and effectiveness.

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.

Innate and adaptive immune response in SARS-CoV-2 infection-Current perspectives

Coronavirus disease 2019 (COVID-19) has been a global pandemic, caused by a novel coronavirus strain with strong infectivity, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). With the in-depth research, the close relationship between COVID-19 and immune system has been dug out. During the infection, macrophages, dendritic cells, natural killer cells, CD8⁺ T cells, Th1, Th17, Tfh cells and effector B cells are all involved in the anti-SARS-CoV-2 responses, however, the dysfunctional immune responses will ultimately lead to the excessive inflammation, acute lung injury, even other organ failure. Thus, a detailed understanding of pertinent immune response during COVID-19 will provide insights in predicting disease outcomes and developing appropriate therapeutic approaches. In this review, we mainly clarify the role of immune cells in COVID-19 and the target-vaccine development and treatment.

Mucosal delivery of nanovaccine strategy against COVID-19 and its variants

Despite the global administration of approved COVID-19 vaccines (e.g., ChAdOx1 nCoV-19®, mRNA-1273®, BNT162b2®), the number of infections and fatalities continue to rise at an alarming rate because of the new variants such as Omicron and its subvariants. Including COVID-19 vaccines that are licensed for human use, most of the vaccines that are currently in clinical trials are administered via parenteral route. However, it has been proven that the parenteral vaccines do not induce localized immunity in the upper respiratory mucosal surface, and administration of the currently approved vaccines does not necessarily lead to sterilizing immunity. This further supports the necessity of a mucosal vaccine that blocks the main entrance route of COVID-19: nasal and oral mucosal surfaces. Understanding the mechanism of immune regulation of M cells and dendritic cells and targeting them can be another promising approach for the successful stimulation of the mucosal immune system. This paper reviews the basic mechanisms of the mucosal immunity elicited by mucosal vaccines and summarizes the practical aspects and challenges of nanotechnology-based vaccine platform development, as well as ligand hybrid nanoparticles as potentially effective target delivery agents for mucosal vaccines.

A vaccine based on the yeast-expressed receptor-binding domain (RBD) elicits broad immune responses against SARS-CoV-2 variants

Development of safe and efficient vaccines is still necessary to deal with the COVID-19 pandemic. Herein, we reported that yeast-expressed recombinant RBD proteins either from wild-type or Delta SARS-CoV-2 were able to elicit immune responses against SARS-CoV-2 and its variants. The wild-type RBD (wtRBD) protein was overexpressed in Pichia pastoris, and the purified protein was used as the antigen to immunize mice after formulating an aluminium hydroxide (Alum) adjuvant. Three immunization programs with different intervals were compared. It was found that the immunization with an interval of 28 days exhibited the strongest immune response to SARS-CoV-2 than the one with an interval of 14 or 42 days based on binding antibody and the neutralizing antibody (NAb) analyses. The antisera from the mice immunized with wtRBD were able to neutralize the Beta variant with a similar efficiency but the Delta variant with 2~2.5-fold decreased efficiency. However, more NAbs to the Delta variant were produced when the Delta RBD protein was used to immunize mice. Interestingly, the NAbs may cross react with the Omicron variant. To increase the production of NAbs, the adjuvant combination of Alum and CpG oligonucleotides was used. Compared with the Alum adjuvant alone, the NAbs elicited by the combined adjuvants exhibited an approximate 10-fold increase for the Delta and a more than 53-fold increase for the Omicron variant. This study suggested that yeast-derived Delta RBD is a scalable and an effective vaccine candidate for SARS-CoV-2 and its variants.

Development of Nasal Vaccines and the Associated Challenges

Viruses, bacteria, fungi, and several other pathogenic microorganisms usually infect the host via the surface cells of respiratory mucosa. Nasal vaccination could provide a strong mucosal and systemic immunity to combat these infections. The intranasal route of vaccination offers the advantage of easy accessibility over the injection administration. Therefore, nasal immunization is considered a promising strategy for disease prevention, particularly in the case of infectious diseases of the respiratory system. The development of a nasal vaccine, particularly the strategies of adjuvant and antigens design and optimization, enabling rapid induction of protective mucosal and systemic responses against the disease. In recent times, the development of efficacious nasal vaccines with an adequate safety profile has progressed rapidly, with effective handling and overcoming of the challenges encountered during the process. In this context, the present report summarizes the most recent findings regarding the strategies used for developing nasal vaccines as an efficient alternative to conventional vaccines.

COVID-19 Vaccinating Russian Medical Students-Challenges and Solutions: A Cross-Sectional Study

Background: The role of preventive measures increases significantly in the absence of effective specific COVID-19 treatment. Mass population immunization and the achievement of collective immunity are of particular importance. The future development of public attitudes towards SARS-CoV-2 immunization depends significantly on medical students, as future physicians. Therefore, it seemed relevant to determine the percentage of COVID-19-vaccinated medical students and to identify the factors significantly affecting this indicator. Methods: A total of 2890 medical students from years one to six, studying at nine leading Russian medical universities, participated in an anonymous sociological survey. The study was performed in accordance with the STROBE guidelines. Results: It was found that the percentage of vaccinated Russian medical students at the beginning of the academic year 2021 was 58.8 ± 7.69%, which did not significantly differ from the vaccination coverage of the general population in the corresponding regions (54.19 ± 4.83%). Student vaccination rate was largely determined by the region-specific epidemiological situation. The level of student vaccination coverage did not depend on the gender or student residence (in a family or in a university dormitory). The group of senior students had a higher number of COVID-19 vaccine completers than the group of junior students. The lack of reliable information about COVID-19 vaccines had a pronounced negative impact on the SARS-CoV-2 immunization process. Significant information sources influencing student attitudes toward vaccination included medical professionals, medical universities, academic conferences, and manuscripts, which at that time provided the least information. Conclusion: The obtained results make it possible to develop recommendations to promote SARS-CoV-2 immunoprophylaxis among students and the general population and to increase collective immunity.

Comparison of Physical and Biochemical Characterizations of SARS-CoV-2 Inactivated by Different Treatments

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused huge social and economic distress. Given its rapid spread and the lack of specific treatment options, SARS-CoV-2 needs to be inactivated according to strict biosafety measures during laboratory diagnostics and vaccine development. The inactivation method for SARS-CoV-2 affects research related to the natural virus and its immune activity as an antigen in vaccines. In this study, we used size exclusion chromatography, western blotting, ELISA, an electron microscope, dynamic light scattering, circular dichroism, and surface plasmon resonance to evaluate the effects of four different chemical inactivation methods on the physical and biochemical characterization of SARS-CoV-2. Formaldehyde and β-propiolactone (BPL) treatment can completely inactivate the virus and have no significant effects on the morphology of the virus. None of the four tested inactivation methods affected the secondary structure of the virus, including the α-helix, antiparallel β-sheet, parallel β-sheet, β-turn, and random coil. However, formaldehyde and long-term BPL treatment (48 h) resulted in decreased viral S protein content and increased viral particle aggregation, respectively. The BPL treatment for 24 h can completely inactivate SARS-CoV-2 with the maximum retention of the morphology, physical properties, and the biochemical properties of the potential antigens of the virus. In summary, we have established a characterization system for the comprehensive evaluation of virus inactivation technology, which has important guiding significance for the development of vaccines against SARS-CoV-2 variants and research on natural SARS-CoV-2.

Viral vector and nucleic acid vaccines against COVID-19: A narrative review

After about 2 years since the first detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in Wuhan, China, in December 2019 that resulted in a worldwide pandemic, 6.2 million deaths have been recorded. As a result, there is an urgent need for the development of a safe and effective vaccine for coronavirus disease 2019 (COVID-19). Endeavors for the production of effective vaccines inexhaustibly are continuing. At present according to the World Health Organization (WHO) COVID-19 vaccine tracker and landscape, 153 vaccine candidates are developing in the clinical phase all over the world. Some new and exciting platforms are nucleic acid-based vaccines such as Pfizer Biontech and Moderna vaccines consisting of a messenger RNA (mRNA) encoding a viral spike protein in host cells. Another novel vaccine platform is viral vector vaccine candidates that could be replicating or nonreplicating. These types of vaccines that have a harmless viral vector like adenovirus contain a genome encoding the spike protein of SARS-CoV-2, which induces significant immune responses. This technology of vaccine manufacturing has previously been used in many human clinical trials conducted for adenoviral vector-based vaccines against different infectious agents, including Ebola virus, Zika virus, HIV, and malaria. In this paper, we have a review of nucleic acid-based vaccines that are passing their phase 3 and 4 clinical trials and discuss their efficiency and adverse effects.

Subacute thyroiditis with liver dysfunction following coronavirus disease 2019 (COVID-19) vaccination: report of two cases and a literature review

Subacute thyroiditis is a transient inflammatory thyroid disease characterized by neck pain, fever, and typical symptoms associated with thyrotoxicosis. The incidence of subacute thyroiditis is higher in female than in male, and susceptibility is prominent in the 30-50-year age range. The variety of case reports on subacute thyroiditis associated with coronavirus disease 2019 (COVID-19) appears to be increasing, and subacute thyroiditis following COVID-19 vaccination has recently been reported. Herein, we report two cases of subacute thyroiditis that developed after receiving the COVID-19 mRNA vaccine, one of which exhibited remarkable liver dysfunction. The mechanism underlying the development of post-vaccination subacute thyroiditis remains unknown; however, one theory suggests that adjuvants contained in vaccines may play a role in triggering diverse autoimmune and inflammatory responses. Another possibility is the potential cross-reactivity between the coronavirus spike protein target produced by the mRNA vaccine and thyroid cell antigens. Common side effects of the COVID-19 vaccine include pain at the injection site, fever, fatigue, headache, muscle pain, chills, and nausea. These symptoms are usually resolved within a few days. Subacute thyroiditis may present symptoms similar to those of short-term vaccination side effects or exhibit non-specific symptoms, potentially leading to misdiagnosis or underdiagnosis. Therefore, clinicians should be aware of the possible development of subacute thyroiditis after COVID-19 vaccination.

Factors influencing physician's behavioral intention to use Traditional Chinese Medicine to treat coronavirus disease 2019 based on the theory of planned behavior

OBJECTIVE

To explore the factors influencing physicians' intentions to use Traditional Chinese Medicine (TCM) to treat coronavirus disease 2019 (COVID-19).

METHODS

A cross-sectional, self-report online survey was conducted from March 16, 2020, to April 2, 2020, in China. Participants were recruited through convenience and snowball sampling. Data were collected by using a self-designed questionnaire based on the Theory of Planned Behavior. Structural equation modeling was used for data analysis.

RESULTS

A total of 494 physicians were enrolled in this study. Overall, the model explained 75.4% and 75.5% of the total variance in intention and attitude, respectively. Specifically, attitudes (β = 0.467, P < 0.001), past behavior (β = 0.384, P < 0.05), subjective norms (SN) (β = 0.177, P < 0.001), and perceived behavioral control (PBC) (β = 0.133, P < 0.05) significantly affected physicians' intention to use TCM. Cognition (β = 0.606, P < 0.001) and PBC (β = 0.569, P < 0.01) significantly influenced physicians' attitudes toward using TCM. SN (β = 0.064, P = 0.263) was not a factor affecting attitude.

CONCLUSION

Physicians' intention to use TCM was significantly associated with attitude, past behavior, PBC, and SN. The findings may not only be useful for understanding the influencing factors and paths of physicians' intention to use TCM to treat COVID-19 but also provide a reference for health authorities and policymakers to promote physicians to utilize TCM.

Cross-variant protection against SARS-CoV-2 infection in hamsters immunized with monovalent and bivalent inactivated vaccines

Rapid development and successful use of vaccines against SARS-CoV-2 might hold the key to curb the ongoing pandemic of COVID-19. Emergence of vaccine-evasive SARS-CoV-2 variants of concern (VOCs) has posed a new challenge to vaccine design and development. One urgent need is to determine what types of variant-specific and bivalent vaccines should be developed. Here, we compared homotypic and heterotypic protection against SARS-CoV-2 infection of hamsters with monovalent and bivalent whole-virion inactivated vaccines derived from representative VOCs. In addition to the ancestral SARS-CoV-2 Wuhan strain, Delta (B.1.617.2; δ) and Theta (P.3; θ) variants were used in vaccine preparation. Additional VOCs including Omicron (B.1.1.529) and Alpha (B.1.1.7) variants were employed in the challenge experiment. Consistent with previous findings, Omicron variant exhibited the highest degree of immune evasion, rendering all different forms of inactivated vaccines substantially less efficacious. Notably, monovalent and bivalent Delta variant-specific inactivated vaccines provided optimal protection against challenge with Delta variant. Yet, some cross-variant protection against Omicron and Alpha variants was seen with all monovalent and bivalent inactivated vaccines tested. Taken together, our findings support the notion that an optimal next-generation inactivated vaccine against SARS-CoV-2 should contain the predominant VOC in circulation. Further investigations are underway to test whether a bivalent vaccine for Delta and Omicron variants can serve this purpose.

Current vaccine strategies against SARS-CoV-2: Promises and challenges

In the years since the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic began and spread across the globe, lessons have been learned about the challenges and opportunities that a pandemic brings to humankind. Researchers have produced many vaccines at unprecedented speed to protect people, but they have also been cognizant of the challenges presented by a new and unexpected infectious disease. The scope of this review is to examine the path of vaccine discovery so far and identify potential targets. Here, we provide insight into the leading vaccines and their advantages and challenges. We discuss the emerging mutations within the SARS-CoV-2 spike protein and other issues that need to be addressed to overcome coronavirus disease 2019 (COVID-19) completely. Future research is needed to develop a cheap, temperature-stable vaccine providing long-term immunity that protects the upper respiratory tract.

Covid-19 vaccines and variants of concern: A review

Since the outbreak of coronavirus disease 2019 (Covid-19) in December 2019, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the number of confirmed infections has risen to more than 242 million worldwide, with nearly 5 million deaths. Currently, nine Covid-19 vaccine candidates based on the original Wuhan-Hu-1 strain are at the forefront of vaccine research. All nine had an efficacy over 50% against symptomatic Covid-19 disease: NVX-CoV2373 (∼96%), BNT162b2 (∼95%), mRNA-1273 (∼94%), Sputnik V (∼92%), AZD1222 (∼81%), BBIBP-CorV (∼79%), Covaxin (∼78%), Ad26.CoV.S (∼66%) and CoronaVac (∼51%). However, vaccine efficacy (VE) can be jeopardised by the rapid emergence and spread of SARS-CoV-2 variants of concern (VOCs) that could escape from neutralising antibodies and/or cell-mediated immunity. Rare adverse events have also been reported soon after administration of viral vector and mRNA vaccines. Although many Covid-19 vaccines have been developed, additional effective vaccines are still needed to meet the global demand. Promising Covid-19 vaccines such as WIBP-CorV, AD5-nCOV, ZyCoV-D, CVnCoV, EpiVacCorona and ZF2001 have advanced to clinical studies. This review describes the most relevant mutations in the SARS-CoV-2 spike protein, discusses VE against VOCs, presents rare adverse events after Covid-19 vaccination and introduces some promising Covid-19 vaccine candidates.

Investigation of Antibody Levels During Three Doses of Sinopharm/BBIBP Vaccine Inoculation

Levels of neutralizing antibodies (NAb) after vaccine against coronavirus disease 2019 (COVID-19) can be detected using a variety of methods. A critical challenge is how to apply simple and accurate methods to assess vaccine effect. In a population inoculated with three doses of the inactivated Sinopharm/BBIBP vaccine, we assessed the performance of chemiluminescent immunoassay (CLIA) in its implementation to detect severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) specific antibodies, as well as the antibody kinetics of healthcare workers throughout the course of vaccination. The antibody levels of NAb, the receptor-binding-domain (RBD) antibodies and IgG peaked one month after the second and remained at a relatively high level for over three months after the booster injection, while IgM and IgA levels remained consistently low throughout the course of vaccination. The production of high-level neutralizing antibodies is more likely when the inoculation interval between the first two doses is within the range of one to two months, and that between the first and booster dose is within 230 days. CLIA showed excellent consistency and correlation between NAb, RBD, and IgG antibodies with the cytopathic effect (CPE) conventional virus neutralization test (VNT). Receiver operating characteristic (ROC) analysis revealed that the optimal cut-off levels of NAb, RBD and IgG were 61.77 AU/ml, 37.86 AU/ml and 4.64 AU/ml, with sensitivity of 0.833, 0.796 and 0.944, and specificity of 0.768, 0.750 and 0.625, respectively, which can be utilized as reliable indicators of COVID-19 vaccination immunity detection.

Bergamottin, a bioactive component of bergamot, inhibits SARS-CoV-2 infection in golden Syrian hamsters

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused an ongoing pandemic, coronavirus disease-2019 (COVID-19), which has become a major global public health event. Antiviral compounds remain the predominant means of treating COVID-19. Here, we reported that bergamottin, a furanocoumarin originally found in bergamot, exhibited inhibitory activity against SARS-CoV-2 in vitro, ex vivo, and in vivo. Bergamottin interfered with multiple stages of virus life cycles, specifically blocking the SARS-CoV-2 spike-mediated membrane fusion and effectively reducing viral RNA synthesis. Oral delivery of bergamottin to golden Syrian hamsters at dosages of both 50 mg/kg and 75 mg/kg reduced the SARS-CoV-2 load in nasal turbinates and lung tissues. Pathological damage caused by viral infection was also ameliorated after bergamottin treatment. Overall, our study provides evidence of bergamottin as a promising natural compound, with broad-spectrum anti-coronavirus activity, that could be further developed in the fight against COVID-19 infection during the current pandemic.

Antibody response to SARS-CoV-2 vaccines among hospitalized patients in China: a case-control study

A lack of confidence on the vaccination drive hinders the management of the COVID-19 pandemic. We aimed to assess the antibody response to the SARS-CoV-2 vaccine among hospitalized patients in China. This case-control study was based on SARS-CoV-2 sero-surveillance during hospitalization. From April to June 2021, hospitalized patients without documented COVID-19 infection from the Department of Urology were routinely assayed for anti-SARS-CoV-2 antibodies. The SARS-CoV-2 vaccination history of each participant was obtained from their vaccination records. Of the 405 participants, there were 37 seropositive participants (case group) and 368 seronegative participants (control group); 68 participants (16.8%) had received the inactivated SARS-CoV-2 vaccine, including 54 who received the Sinovac-CoronaVac vaccine and 14 received the Sinopharm vaccine. All seropositive participants who had received one or two doses of the SARS-CoV-2 vaccine were assessed for at least 16 days, while 31 (8.4%) of 368 seronegative controls who had received the vaccine were tested for 1–94 days. The overall seroconversion rate was 54.4% (37/68) in the vaccinated participants who received the inactivated SARS-CoV-2 vaccine. The odds ratio (OR) and confidence interval (CI) for seropositivity was 6.20 (95% CI: 2.05–18.71) in those received full vaccination with two doses versus those partially vaccinated participants with one dose after adjusting for sex and age. These findings imply that the inactivated SARS-CoV-2 vaccine could have a protective antibody response.

Development of a rapid neutralizing antibody test for SARS-CoV-2 and its application for neutralizing antibody screening and vaccinated serum testing

Background

Since the outbreak of coronavirus disease (COVID-19), the high infection rate and mutation frequency of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent, have contributed to the ongoing global pandemic. Vaccination has become the most effective means of controlling COVID-19. Traditional neutralizing tests of sera are complex and labor-intensive, therefore, a rapid test for detecting neutralizing antibodies and antibody status post-immunization is needed.

Methods

Based on the fact that antibodies exhibit neutralizing activity by blocking the binding of the S protein receptor-binding domain (S-RBD) to ACE2, we developed a rapid neutralizing antibody test, ACE2-Block-ELISA. To evaluate the sensitivity and specificity, we used 54 positive and 84 negative serum samples. We also tested the neutralizing activities of monoclonal antibodies (mAbs) and 214 sera samples from healthy individuals immunized with the inactivated SARS-CoV-2 vaccine.

Results

The sensitivity and specificity of the ACE2-Block ELISA were 96.3% and 100%, respectively. For neutralizing mAb screening, ch-2C5 was selected for its ability to block the ACE2-S-RBD interaction. A plaque assay confirmed that ch-2C5 neutralized SARS-CoV-2, with NT50 values of 4.19, 10.63, and 1.074 µg/mL against the SARS-CoV-2 original strain, and the Beta and Delta variants, respectively. For the immunized sera samples, the neutralizing positive rate dropped from 82.14% to 32.16% within 4 months post-vaccination.

Conclusions

This study developed and validated an ACE2-Block-ELISA to test the neutralizing activities of antibodies. As a rapid, inexpensive and easy-to-perform method, this ACE2-Block-ELISA has potential applications in rapid neutralizing mAb screening and SARS-CoV-2 vaccine evaluation.

Seroprevalence of SARS-CoV-2-specific antibodies and vaccination-related adverse events in systemic lupus erythematosus and rheumatoid arthritis

Background

This study aimed to investigate the seroreactivity of Coronavirus disease 2019 (COVID-19) vaccination and its adverse events among systemic lupus erythematosus (SLE) patients, rheumatoid arthritis (RA) patients, and healthy controls (HCs).

Methods

A total of 60 SLE patients, 70 RA patients and 35 HCs, who received a complete inactivated COVID-19 vaccine (Vero cells) regimen, were recruited in the current study. Serum IgG and IgM antibodies against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) were determined by using chemiluminescent microparticle immunoassay (CMIA).

Results

There were no significant differences regarding the seroprevalences of IgG and IgM antibodies against SARS-CoV-2, and the self-reported vaccination-related adverse events among SLE patients, RA patients and HCs. The inactivated COVID-19 vaccines appeared to be well-tolerated and moderately immunogenic. In addition, case-only analysis indicated that in SLE patients, the disease manifestation of rash and anti-SSA autoantibody were associated with seroprevalence of IgG antibody against SARS-CoV-2, whereas the uses of ciclosporin and leflunomide had influence on the seroprevalence of IgM antibody against SARS-CoV-2. In RA patients, rheumatoid factor (RF) appeared to be associated with the seroprevalence of IgG antibody against SARS-CoV-2.

Conclusion

Our study reveals that the seroprevalences of IgG and IgM antibodies against SARS-CoV-2 and vaccination-related adverse effects are similar among SLE, RA and HCs, suggesting that COVID-19 vaccine is safe and effective for SLE and RA patients to prevent from the pandemic of COVID-19.