Development of an Inactivated Vaccine Candidate, BBIBP-CorV, with Potent Protection against SARS-CoV-2

Considerations for the Feasibility of Neutralizing Antibodies as a Surrogate Endpoint for COVID-19 Vaccines

To effectively control and prevent the pandemic of coronavirus disease 2019 (COVID-19), suitable vaccines have been researched and developed rapidly. Currently, 31 COVID-19 vaccines have been approved for emergency use or authorized for conditional marketing, with more than 9.3 billion doses of vaccines being administered globally. However, the continuous emergence of variants with high transmissibility and an ability to escape the immune responses elicited by vaccines poses severe challenges to the effectiveness of approved vaccines. Hundreds of new COVID-19 vaccines based on different technology platforms are in need of a quick evaluation for their efficiencies. Selection and enrollment of a suitable sample of population for conducting these clinical trials is often challenging because the pandemic so widespread and also due to large scale vaccination. To overcome these hurdles, methods of evaluation of vaccine efficiency based on establishment of surrogate endpoints could expedite the further research and development of vaccines. In this review, we have summarized the studies on neutralizing antibody responses and effectiveness of the various COVID-19 vaccines. Using this data we have analyzed the feasibility of establishing surrogate endpoints for evaluating the efficacy of vaccines based on neutralizing antibody titers. The considerations discussed here open up new avenues for devising novel approaches and strategies for the research and develop as well as application of COVID-19 vaccines.

Vaccines for COVID-19: A Systematic Review of Immunogenicity, Current Development, and Future Prospects

The persistent coronavirus disease 2019 (COVID-19), characterized by severe respiratory syndrome, is caused by coronavirus 2 (SARS-CoV-2), and it poses a major threat to public health all over the world. Currently, optimal COVID-19 management involves effective vaccination. Vaccination is known to greatly enhance immune response against viral infections and reduce public transmission of COVID-19. However, although current vaccines offer some benefits, viral variations and other factors demand the continuous development of vaccines to eliminate this virus from host. Hence, vaccine research and development is crucial and urgent to the elimination of this pandemic. Herein, we summarized the structural and replicatory features of SARS-CoV-2, and focused on vaccine-mediated disease prevention strategies like vaccine antigen selection, vaccine research, and vaccine application. We also evaluated the latest literature on COVID-19 and extensively reviewed action mechanisms, clinical trial (CT) progresses, advantages, as well as disadvantages of various vaccine candidates against SARS-CoV-2. Lastly, we discussed the current viral treatment, prevention trends, and future prospects.

Ischemic colitis after receiving the second dose of a COVID-19 inactivated vaccine: A case report

BACKGROUND

The outbreak of the coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 has been the most important clinical challenge worldwide since January 2020. COVID-19 inactivated vaccines play a crucial role in reducing the rates of morbidity and mortality.

CASE SUMMARY

We presented a 48-year-old woman from Haidian District, Beijing, China who developed ischemic colitis after receiving the second dose of COVID-19 inactivated vaccine. Computed tomography of the abdomen showed edema and bowel wall thickening with hypodensity in the sigmoid colon and descending colon. Colonoscopy revealed hyperemia, edema and erosion of the mucosa with superficial ulceration and a yellow-white coating at the descending colon and sigmoid colon. The symptoms were relieved after 1 wk of receiving pinaverium bromide (50 mg, tid) and aspirin enteric-coated tablets (0.1 g, qd).

CONCLUSION

The possible occurrence of ischemic colitis should be considered after administration of the COVID-19 inactivated vaccines.

Long-term persistence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein-specific and neutralizing antibodies in recovered COVID-19 patients

Understanding antibody responses after natural severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can guide the coronavirus disease 2019 (COVID-19) vaccine schedule, especially in resource-limited settings. This study aimed to assess the dynamics of SARS-CoV-2 antibodies, including anti-spike protein 1 (S1) immunoglobulin (Ig)G, anti-receptor-binding domain (RBD) total Ig, anti-S1 IgA, and neutralizing antibody against wild-type SARS-CoV-2 over time in a cohort of patients who were previously infected with the wild-type SARS-CoV-2. Between March and May 2020, 531 individuals with virologically confirmed cases of wild-type SARS-CoV-2 infection were enrolled in our immunological study. Blood samples were collected at 3-, 6-, 9-, and 12-months post symptom onset or detection of SARS-CoV-2 by RT-PCR (in asymptomatic individuals). The neutralizing titers against SARS-CoV-2 were detected in 95.2%, 86.7%, 85.0%, and 85.4% of recovered COVID-19 patients at 3, 6, 9, and 12 months after symptom onset, respectively. The seropositivity rate of anti-S1 IgG, anti-RBD total Ig, anti-S1 IgA, and neutralizing titers remained at 68.6%, 89.6%, 77.1%, and 85.4%, respectively, at 12 months after symptom onset. We observed a high level of correlation between neutralizing and SARS-CoV-2 spike protein-specific antibody titers. The half-life of neutralizing titers was estimated at 100.7 days (95% confidence interval = 44.5–327.4 days, R² = 0.106). These results support that the decline in serum antibody levels over time in both participants with severe disease and mild disease were depended on the symptom severity, and the individuals with high IgG antibody titers experienced a significantly longer persistence of SARS-CoV-2-specific antibody responses than those with lower titers.

Vaccines for Covid-19: An Insight on Their Effectiveness and Adverse Effects

An Era of SARS-COVID-19 out broke with a high contagious percentage around the globe has been the subject of multi-agency research aimed at generating vaccines for active immunization. Scientists across the world are joining hands for the advanced tie-ups between the medical start-ups and the pharmaceutical industries for devices and vaccines development to hinder the progress of this outbreak. Moreover, the questions that need to be answered are how to improve the effectiveness and efficacy of vaccines with reduced side effects and the required doses of vaccines for enhanced surveillance. In this review article, we have discussed the effectiveness and efficacy of different Covid-19 vaccines. This article is protected by copyright. All rights reserved.

A single intranasal dose of human parainfluenza virus type 3-vectored vaccine induces effective antibody and memory T cell response in the lungs and protects hamsters against SARS-CoV-2

Respiratory tract vaccination has an advantage of needle-free delivery and induction of mucosal immune response in the portal of SARS-CoV-2 entry. We utilized human parainfluenza virus type 3 vector to generate constructs expressing the full spike (S) protein of SARS-CoV-2, its S1 subunit, or the receptor-binding domain, and tested them in hamsters as single-dose intranasal vaccines. The construct bearing full-length S induced high titers of neutralizing antibodies specific to S protein domains critical to the protein functions. Robust memory T cell responses in the lungs were also induced, which represent an additional barrier to infection and should be less sensitive than the antibody responses to mutations present in SARS-CoV-2 variants. Following SARS-CoV-2 challenge, animals were protected from the disease and detectable viral replication. Vaccination prevented induction of gene pathways associated with inflammation. These results indicate advantages of respiratory vaccination against COVID-19 and inform the design of mucosal SARS-CoV-2 vaccines.

Repeat-dose and local tolerance toxicity of SARS-CoV-2 FINLAY-FR-02 vaccine candidate in Sprague Dawley rats

This study evaluates safety of FINLAY-FR-02, a vaccine candidate against SARS-CoV-2 based on the recombinant receptor binding domain conjugated to tetanus toxoid, in a preclinical, repeat-dose toxicity and local tolerance study. Sprague Dawley rats were randomly allocated to three experimental groups: control (receiving physiological saline solution); placebo (receiving all vaccine components except antigens) and vaccine group (receiving three doses of the vaccine candidate, 37.5 µg of RBD) administered intramuscularly in hind limbs at 24 h intervals during three days. We evaluated physiological condition, pain, food and water consumption, body temperature, dermal irritability, injection site temperature and inflammation, immunological response, blood chemistry, relative organ weight, histopathology and immunotoxicology. The product was well tolerated; no clinically relevant changes, pain, local effects or adverse systemic toxicological changes or deaths were observed. These preliminary results permitted the Cuban regulatory authorities to authorize clinical trials in humans.

Safety and Immunogenicity of COVID-19 BBIBP-CorV Vaccine in Children 3–12 Years Old

Background and Objectives: In the current COVID-19 pandemic, children below the age of 12 could manifest COVID-19 symptoms and serve as a reservoir for the virus in the community. The present study was conducted to evaluate the reactogenicity, and immunogenicity of BBIBP-CorV, prior to involving this age group in the vaccination program in the kingdom of Bahrain. Subjects and Methods: The study included 582 children from 3 to 12 years old of Bahraini and non-Bahraini nationality, all of which contributed to the reactogenicity study. Of those, 401 contributed to the immunogenicity study. All children received 2 doses of BBIBP-CorV inactivated virus 3 weeks apart. To assess reactogenicity, children were followed up for 5 weeks to evaluate any vaccine-related adverse events (AE). To assess immunogenicity, blood was collected on day 0 and day 35 to assess antibody titer against S, N, and neutralizing antibody. Results: Of the 582 participants, (45.4%) were female, (54.61%) were male, with 49% in 9–12 age group. Of the 401 children contributing to the immunogenicity study, 274 (68.3%) had no prior exposure to COVID-19. The overall incidence of AE was 27.7%. No significant difference was found among different age groups. The most frequent AE was local (at the injection site) and occurred in 16% of children, followed by fever in 9.3%. No serious adverse events were reported. The Seroconversion rate was 100% among children with no prior exposure to COVID-19. Children with previous COVID-19 exposure had higher averages of anti-S (2379 U/mL compared to 409.1), anti-N (177.6 U/mL compared to 30.9) and neutralizing antibody (93.7 U/mL compared to 77.1) than children with no prior exposure at day 35. Conclusions: Two doses of COVID-19 BBIBP-CorV on the subjects aged between 3 to 12 has good safety and tolerance and can induce an effective immune response and neutralizing antibody titer.

Alum Adjuvant and Built-in TLR7 Agonist Synergistically Enhance Anti-MUC1 Immune Responses for Cancer Vaccine

The tumor-associated antigen mucin 1 (MUC1) is an attractive target of antitumor vaccine, but its weak immunogenicity is a big challenge for the development of vaccine. In order to enhance immune responses against MUC1, herein, we conjugated small molecular toll-like receptor 7 agonist (TLR7a) to carrier protein BSA via MUC1 glycopeptide to form a three-component conjugate (BSA-MUC1-TLR7a). Furthermore, we combined the three-component conjugate with Alum adjuvant to explore their synergistic effects. The immunological studies indicated that Alum adjuvant and built-in TLR7a synergistically enhanced anti-MUC1 antibody responses and showed Th1-biased immune responses. Meanwhile, antibodies elicited by the vaccine candidate effectively recognized tumor cells and induced complement-dependent cytotoxicity. In addition, Alum adjuvant and built-in TLR7a synergistically enhanced MUC1 glycopeptide-specific memory CD8+ T-cell immune responses. More importantly, the vaccine with the binary adjuvant can significantly inhibit tumor growth and prolong the survival time of mice in the tumor challenge experiment. This novel vaccine construct provides an effective strategy to develop antitumor vaccines.

Oral SARS-CoV-2 Spike Protein Recombinant Yeast Candidate Prompts Specific Antibody and Gut Microbiota Reconstruction in Mice

A recent study showed that patients with coronavirus disease 2019 (COVID-19) have gastrointestinal symptoms and intestinal flora dysbiosis. Yeast probiotics shape the gut microbiome and improve immune homeostasis. In this study, an oral candidate of yeast-derived spike protein receptor-binding domain (RBD) and fusion peptide displayed on the surface of the yeast cell wall was generated. The toxicity and immune efficacy of oral administration were further performed in Institute of Cancer Research (ICR) mice. No significant difference in body weights, viscera index, and other side effects were detected in the oral-treated group. The detectable RBD-specific immunoglobulin G (IgG) and immunoglobulin A (IgA) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and more complex microbiota were detected from oral administration mice compared with those of the control group. Interestingly, the recombinant yeast was identified in female fetal of the high-dose group. These results revealed that the displaying yeast could fulfill the agent-driven immunoregulation and gut microbiome reconstitution. The findings will shed light on new dimensions against SARS-CoV-2 infection with the synergistic oral agents as promising non-invasive immunization and restoring gut flora.

Advances in Pathogenesis, Progression, Potential Targets and Targeted Therapeutic Strategies in SARS-CoV-2-Induced COVID-19

As the new year of 2020 approaches, an acute respiratory disease quietly caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as coronavirus disease 2019 (COVID-19) was reported in Wuhan, China. Subsequently, COVID-19 broke out on a global scale and formed a global public health emergency. To date, the destruction that has lasted for more than two years has not stopped and has caused the virus to continuously evolve new mutant strains. SARS-CoV-2 infection has been shown to cause multiple complications and lead to severe disability and death, which has dealt a heavy blow to global development, not only in the medical field but also in social security, economic development, global cooperation and communication. To date, studies on the epidemiology, pathogenic mechanism and pathological characteristics of SARS-CoV-2-induced COVID-19, as well as target confirmation, drug screening, and clinical intervention have achieved remarkable effects. With the continuous efforts of the WHO, governments of various countries, and scientific research and medical personnel, the public's awareness of COVID-19 is gradually deepening, a variety of prevention methods and detection methods have been implemented, and multiple vaccines and drugs have been developed and urgently marketed. However, these do not appear to have completely stopped the pandemic and ravages of this virus. Meanwhile, research on SARS-CoV-2-induced COVID-19 has also seen some twists and controversies, such as potential drugs and the role of vaccines. In view of the fact that research on SARS-CoV-2 and COVID-19 has been extensive and in depth, this review will systematically update the current understanding of the epidemiology, transmission mechanism, pathological features, potential targets, promising drugs and ongoing clinical trials, which will provide important references and new directions for SARS-CoV-2 and COVID-19 research.

Detailed analysis of antibody responses to SARS-CoV-2 vaccination and infection in macaques

Macaques are a commonly used model for studying immunity to human viruses, including for studies of SARS-CoV-2 infection and vaccination. However, it is unknown whether macaque antibody responses resemble the response in humans. To answer this question, we employed a phage-based deep mutational scanning approach (Phage-DMS) to compare which linear epitopes are targeted on the SARS-CoV-2 Spike protein in convalescent humans, convalescent (re-infected) rhesus macaques, mRNA-vaccinated humans, and repRNA-vaccinated pigtail macaques. We also used Phage-DMS to determine antibody escape pathways within each epitope, enabling a granular comparison of antibody binding specificities at the locus level. Overall, we identified some common epitope targets in both macaques and humans, including in the fusion peptide (FP) and stem helix-heptad repeat 2 (SH-H) regions. Differences between groups included a response to epitopes in the N-terminal domain (NTD) and C-terminal domain (CTD) in vaccinated humans but not vaccinated macaques, as well as recognition of a CTD epitope and epitopes flanking the FP in convalescent macaques but not convalescent humans. There was also considerable variability in the escape pathways among individuals within each group. Sera from convalescent macaques showed the least variability in escape overall and converged on a common response with vaccinated humans in the SH-H epitope region, suggesting highly similar antibodies were elicited. Collectively, these findings suggest that the antibody response to SARS-CoV-2 in macaques shares many features with humans, but with substantial differences in the recognition of certain epitopes and considerable individual variability in antibody escape profiles, suggesting a diverse repertoire of antibodies that can respond to major epitopes in both humans and macaques. Differences in macaque species and exposure type may also contribute to these findings.

Scope of SARS-CoV-2 variants, mutations, and vaccine technologies

Background

The COVID-19 pandemic is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). SARS-CoV-2 is disseminated by respiratory aerosols. The virus uses the spike protein to target epithelial cells by binding to the ACE2 receptor on the host cells. As a result, effective vaccines must target the viral spike glycoprotein. However, the appearance of an Omicron variant with 32 mutations in its spike protein raises questions about the vaccine's efficacy. Vaccines are critical in boosting immunity, lowering COVID-19-related illnesses, reducing the infectious burden on the healthcare system, and reducing economic loss, according to current data. An efficient vaccination campaign is projected to increase innate and adaptive immune responses, offering better protection against SARS-CoV-2 variants.

Main body

The presence of altered SARS-CoV-2 variants circulating around the world puts the effectiveness of vaccines already on the market at risk. The problem is made even worse by the Omicron variant, which has 32 mutations in its spike protein. Experts are currently examining the potential consequences of commercial vaccines on variants. However, there are worries about the vaccines' safety, the protection they provide, and whether future structural changes are required for these vaccines to be more effective. As a result of these concerns, new vaccines based on modern technology should be developed to guard against the growing SARS-CoV-2 variations.

Conclusion

The choice of a particular vaccine is influenced by several factors including mode of action, storage conditions, group of the vaccinee, immune response mounted, cost, dosage protocol, age, and side effects. Currently, seven SARS-CoV-2 vaccine platforms have been developed. This comprises of inactivated viruses, messenger RNA (mRNA), DNA vaccines, protein subunits, nonreplicating and replicating vector viral-like particles (VLP), and live attenuated vaccines. This review focuses on the SARS-CoV-2 mutations, variants of concern (VOCs), and advances in vaccine technologies.

The Immune Response, Safety, and Efficacy of Emergency Use Authorization-Granted COVID-19 Vaccines: A Review

COVID-19 has affected millions of people, causing a burden on healthcare systems as well as economies throughout the world. Antiviral drugs do not work well enough for everyone. The mortality rate in the world is still significant. Developing safe, effective, affordable, and fast-acting vaccines for COVID-19 is critical for reducing new viral strains in this pandemic and re-establishing normality in the future. Therefore, several pharmaceutical companies are racing to develop effective vaccines for COVID-19. Scientists have developed different kinds of candidate vaccines with various platforms. By March 2021, thirteen vaccines were approved for emergency use in several countries across the world, whilst over 90 vaccine candidates were under clinical trials. There are also several vaccine candidates in Phase 3 trials awaiting results and approval for their use. These candidate vaccines revealed positive results in the previous phase trials, whereby they can induce an immune response with less adverse reaction in the participants. This review focuses on the development of COVID-19 vaccines and highlights the efficacy and adverse reactions of vaccines authorized for emergency use.

Dynamics of specific antibodies in COVID-19 patients after recovery

The ongoing pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to an unprecedented global public health crisis. The objectives of this study were to analyse the dynamic trend in specific antibodies in the serum of patients infected with SARS-CoV-2 within 12 months after recovery and to make a preliminary assessment of the protective effect of vaccination. Eighty-seven patients with confirmed COVID-19 who were admitted to our hospital from January to February 2020 were followed after recovery. Three-millilitre blood samples were collected for specific antibody detection at four time points: 1, 6 and 12 months after recovery and 1 month after vaccination. The changes in specific immunoglobulin G (IgG) antibody and total antibody levels over 12 months were analysed. Moreover, an independent comparison of the neutralising antibody levels of patients after vaccination with those of healthy medical staff after vaccination was performed to compare the inhibition rates of the neutralising antibody to the virus. No statistically significant difference in the sex distribution between groups was observed (P > 0.05). Older patients had a greater risk of developing severe and critical COVID-19 (P < 0.05). The percentages of subjects positive for IgG antibodies at 1, 6 and 12 months after recovery were 88.5%, 75.9% and 50.6%, respectively. The rate of IgG antibody conversion from positive to negative was not uniform across time points: the change was slow in the first 6 months but increased significantly in the last 6 months (P < 0.05). The positive rate of critically ill patients in the first 6 months was 100.0%. The trend over time in total antibody levels was similar to that of IgG antibody levels. Over 12 months, the sample/cut off value of total antibodies continued to decrease, while that of different disease severities was significantly different (P < 0.05). After vaccine administration, the total antibody level exceeded the detection level in the first month, which was independent of disease severity (P > 0.05). Significant differences were observed in the inhibition rate of the neutralising antibody against the virus in the disease group and the control group (P < 0.05). IgG antibody produced by patients naturally infected with SARS-CoV-2 has a duration of no less than 1 year, and the change trend graph of total antibody levels was the same as that of IgG antibody levels. Under vaccine stimulation, the positive rate of IgG antibody was as high as 100%, and the total antibody concentration reached the highest level, which was independent of disease severity. Neutralising antibodies following vaccination in patients who recovered from COVID-19 had a higher inhibition rate against SARS-CoV-2 than those of vaccinated healthy controls, indicating that these COVID-19 patients had a lower risk of reinfection and were better protected.

Toxicity of spike fragments SARS-CoV-2 S protein for zebrafish: A tool to study its hazardous for human health?

Despite the significant increase in the generation of SARS-CoV-2 contaminated domestic and hospital wastewater, little is known about the ecotoxicological effects of the virus or its structural components in freshwater vertebrates. In this context, this study evaluated the deleterious effects caused by SARS-CoV-2 Spike protein on the health of Danio rerio, zebrafish. We demonstrated, for the first time, that zebrafish injected with fragment 16 to 165 (rSpike), which corresponds to the N-terminal portion of the protein, presented mortalities and adverse effects on liver, kidney, ovary and brain tissues. The conserved genetic homology between zebrafish and humans might be one of the reasons for the intense toxic effects followed inflammatory reaction from the immune system of zebrafish to rSpike which provoked damage to organs in a similar pattern as happen in severe cases of COVID-19 in humans, and, resulted in 78,6% of survival rate in female adults during the first seven days. The application of spike protein in zebrafish was highly toxic that is suitable for future studies to gather valuable information about ecotoxicological impacts, as well as vaccine responses and therapeutic approaches in human medicine. Therefore, besides representing an important tool to assess the harmful effects of SARS-CoV-2 in the aquatic environment, we present the zebrafish as an animal model for translational COVID-19 research.

Neutralizing Activities against the Omicron Variant after a Heterologous Booster in Healthy Adults Receiving Two Doses of CoronaVac Vaccination

BACKGROUND

The use of an inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine (CoronaVac) against SARS-CoV-2 is implemented worldwide. However, waning immunity and breakthrough infections have been observed. Therefore, we hypothesized that the heterologous booster might improve the protection against the delta and omicron variants.

METHODS

A total of 224 individuals who completed the two-dose CoronaVac for six months were included. We studied reactogenicity and immunogenicity following a heterologous booster with the inactivated vaccine (BBIBP), the viral vector vaccine (AZD1222), and the mRNA vaccine (both BNT162B2 and mRNA-1273). We also determined immunogenicity at 3- and 6-months boosting intervals.

RESULTS

The solicited adverse events (AEs) were mild to moderate and well-tolerated. Total RBD immunoglobulin (Ig), anti-RBD IgG, focus reduction neutralization test (FRNT50) against delta and omicron variants, and T-cell response were highest in the mRNA-1273 group followed by the BNT162b2, AZD1222 and BBIBP groups, respectively. We also witnessed a higher total Ig anti-RBD in the long-interval than in the short-interval groups.

CONCLUSIONS

All four booster vaccines significantly increased binding and neutralizing antibody (NAbs) in individuals immunized with two doses of CoronaVac. The present evidence may benefit vaccine strategies to thwart variants of concern, including the omicron variant.

Anti-SARS-CoV-2 equine F (Ab')2 immunoglobulin as a possible therapy for COVID-19

The new outbreak of coronavirus disease 2019 (COVID-19) has infected and caused the death of millions of people worldwide. Intensive efforts are underway around the world to establish effective treatments. Immunoglobulin from immunized animals or plasma from convalescent patients might constitute a specific treatment to guarantee the neutralization of the virus in the early stages of infection, especially in patients with risk factors and a high probability of progressing to severe disease. Worldwide, a few clinical trials using anti-SARS-CoV-2 immunoglobulins from horses immunized with the entire spike protein or fragments of it in the treatment of patients with COVID-19 are underway. Here, we describe the development of an anti-SARS-CoV-2 equine F(ab')2 immunoglobulin using a newly developed SARS-CoV-2 viral antigen that was purified and inactivated by radiation. Cell-based and preclinical assays showed that the F(ab')2 immunoglobulin successfully neutralizes the virus, is safe in animal models, and reduces the severity of the disease in a hamster model of SARS-CoV-2 infection and disease.

Immunogenicity mechanism of mRNA vaccines and their limitations in promoting adaptive protection against SARS-CoV-2

Since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19) in late 2019, hundreds of millions of people have been infected worldwide. There have been unprecedented efforts in acquiring effective vaccines to confer protection against the disease. mRNA vaccines have emerged as promising alternatives to conventional vaccines due to their high potency with the capacity for rapid development and low manufacturing costs. In this review, we summarize the currently available vaccines against SARS-CoV-2 in development, with the focus on the concepts of mRNA vaccines, their antigen selection, delivery and optimization to increase the immunostimulatory capability of mRNA as well as its stability and translatability. We also discuss the host immune responses to the SARS-CoV-2 infection and expound in detail, the adaptive immune response upon immunization with mRNA vaccines, in which high levels of spike-specific IgG and neutralizing antibodies were detected after two-dose vaccination. mRNA vaccines have been shown to induce a robust CD8⁺T cell response, with a balanced CD4⁺ T_H1/T_H2 response. We further discuss the challenges and limitations of COVID-19 mRNA vaccines, where newly emerging variants of SARS-CoV-2 may render currently deployed vaccines less effective. Imbalanced and inappropriate inflammatory responses, resulting from hyper-activation of pro-inflammatory cytokines, which may lead to vaccine-associated enhanced respiratory disease (VAERD) and rare cases of myocarditis and pericarditis also are discussed.

Humoral immune response of BBIBP COVID-19 vaccination before and after the booster immunization

Background

The inactivated Sinopharm/BBIBP COVID‐19 vaccine has been widely used in the world and has joined the COVAX vaccine supply program for developing countries. It is also well adapted for usage in low‐ and middle‐income nations due to their low storage requirements.

Objective

This study aims to report on the kinetics, durability, and neutralizing ability of the induced immunity of the BBIBP vaccine, and the intensified antibody response elicited by the booster.

Methods

A total of 353 healthy adult participants, aged 20–74 years, were recruited in this multicenter study. A standard dose of the BBIBP vaccine was administered (Month 0), followed by a second standard dose (Month 1), and a booster dose (after Month 7). Vaccine‐induced virus‐specific antibody levels (SARS‐CoV‐2‐IgA/IgM/IgG), conventional virus neutralization test (cVNT), pseudovirus neutralization test (pVNT), and surrogate virus neutralization test (sVNT) were monitored over multiple time points.

Results

Neutralizing titers induced by the two doses of inactivated vaccine for COVID‐19 peaked at Month 2 and declined to 33.89% at Month 6. Following the booster dose, elevated levels of antibodies were induced for IgA, IgG, and neutralizing antibodies, with neutralizing titer reaching 13.2 times that of before the booster.

Conclusion

By monitoring the antibody titer levels postvaccination, this study has shown that serum antibody levels will decrease over time, but a notable spike in antibody levels postbooster highlights the anamnestic immune response. This signifies that the protection capability has increased following the injection of booster immunization.

Various vaccine platforms in the field of COVID-19

Background

With the emergence of Corona virus Disease-2019, a novel worldwide health disaster is threatening the population. The WHO declared COVID-19 as a pandemic in December 2019, when it first surfaced in Hunan seafood market in Wuhan, South China, and quickly spread far and wide. Different corona virus variants are currently causing concern all across the world.

Main body

It has become critical for our scientists to develop a viable method to prevent infection or the pandemic from spreading globally. Antiviral medicines, oxygen therapy, and immune system stimulation are all used to treat the condition. SARS-CoV-2 undergoes mutation and due to evolutionary pressures, different mutant strains caused various symptoms in different geographical regions and the epidemic is spreading and becoming more fragile, posing a greater risk of mortality. Vaccines are tools to increase our immunity as a precaution, and increasing the global immunization rate can help improve the situation. Recent developments in the field of vaccine platforms are discussed here.

Short conclusion

Vaccines are of highest priority to control and eradicate the viral infectious disease COVID-19 more than any other protective solutions. A number of mutations have occurred and some variants such as alpha, beta, gamma, and delta, and it has now progressed to the new version Omicron, which is a variant of concern. Booster doses are anticipated to function as a barrier to the capacity of the most recent known variety, and more research is needed to determine how effective they will be. This page discusses various technologies employed in the field of COVID-19 vaccine, as well as potential barriers and recent developments in this field.

Association of severity and mortality of Covid-19 cases among acute kidney injury and sexual dimorphism

Introduction

The outbreak of coronavirus disease 2019 (Covid-19) severely impacted global health and economic status. The native receptor-ligand interaction of Angiotensin-converting enzyme 2 (ACE2) and S protein induces host cell pathogenesis via immunosuppression.

Material and Methods

The emerging evidence reports the sex disparity in Covid-19 induced mortality rate which affects abundantly men population. Although the biological interaction of Covid-19 with receptor upregulates the viral genome protein interactions and initiates the predictive multiorgan failure followed by acute kidney injury (AKI) in Covid-19 infected male population.

Conclusion

Besides, the knowledge and lessons learned from the study depict that cellular and molecular links may explain the risk and severity of Covid-19 and AKI in the male population and lead to management of Covid-19 induced AKI. Therefore, this review explored the pathways associated with the pathogenesis of two diseased conditions with sex disparity.

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.

The Prevalence of COVID-19 Infection in Students and Staff at a Private University in Thailand by Rapid SARS-CoV-2 Antigen Detection Assay

The COVID-19 pandemic led to the suspension of all university courses which was followed directly by the implementation of online learning in Thailand. However, online learning was not suitable for all of Thailand. Rangsit University is a famous private university in Thailand and has been affected by this crisis, so it attempted to eliminate online learning by offering vaccination and antigen rapid screening tests to the students and staff who had to attend the university from July to September 2021. 93.71% of the students and staff from Rangsit University who attended the university from July to September 2021 were vaccinated. Only 1.18% of the students and staff were infected. The vaccines used were CoronaVac and AstraZeneca at 66.02% and 33.98%, respectively. The percentage of individuals that were infected after vaccination did not differ between the two vaccines. The percentage of people infected was 0.31% for CoronaVac and 0.29% for AstraZeneca. Other important factors that influenced the infection rate were the initial symptoms and the environment. Individuals who had initial symptoms and had visited areas with high-risk factors had a high possibility of becoming infected. This research is intended to be useful for risk management during the COVID-19 crisis.

Use of analgesics/antipyretics in the management of symptoms associated with COVID-19 vaccination

COVID-19 vaccines are effective and important to control the ongoing pandemic, but vaccine reactogenicity may contribute to poor uptake. Analgesics or antipyretic medications are often used to alleviate vaccine side effects, but their effect on immunogenicity remains uncertain. Few studies have assessed the effect of analgesics/antipyretics on vaccine immunogenicity and reactogenicity. Some studies revealed changes in certain immune response parameters post-vaccination when analgesics/antipyretics were used either prophylactically or therapeutically. Still, there is no evidence that these changes impact vaccine efficacy. Specific data on the impact of analgesic/antipyretic medications on immunogenicity of COVID-19 vaccines are limited. However, available data from clinical trials of licensed vaccines, along with recommendations from public health bodies around the world, should provide reassurance to both healthcare professionals and vaccine recipients that short-term use of analgesics/antipyretics at non-prescription doses is unlikely to affect vaccine-induced immunity.

Neutralization heterogeneity of circulating SARS-CoV-2 variants to sera elicited by a vaccinee or convalescent

COVID-19, which was first reported in December 2019 in China, has caused a global outbreak. Five variants of concern (VOCs) have been identified in different countries since the global pandemic, namely, Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2) and Omicron (B.1.529). Although multiple vaccines have been found to be effective, some of the amino acid changes may increase the infectivity of virus and decrease the sensitivity to antibodies. Here we characterize the VOCs and discuss their sensitivity to antibodies elicited by convalescent and vaccinee sera. In conclusion, several variants display a reduction in the susceptibility to neutralization antibodies generated by natural infection or vaccination, which threatens the containment of the epidemic.

Recent Update of COVID-19 Vaccines

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) has been recently identified as a novel member of beta coronaviruses (CoVs) and the cause of coronavirus disease 2019 (COVID-19). It has been first discovered in China and soon has spread across continents with an escalating number of mortalities. There is an urgent need for developing a COVID-19 vaccine to control the rapid transmission and the deleterious impact of the virus. The potent vaccine should have a good tolerable and efficacious profile to induce target-specific humoral and cellular immune responses. It should also exhibit no or minimal detrimental effects in children, young adults, and elderly people with or without co-morbidities from different racial backgrounds. Previously published findings of SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV) played vital role in the characterization of surface spike proteins as the tool of entry of the SARS-CoV-2 into host cells. It has become evident that SARS-CoVs have high genetic similarity and this implies antecedent vaccination strategies could be implicated in the production of COVID-19 vaccines. Although several vaccines have been approved and rolled out, only a handful of them have passed the three phases of clinical studies. This review highlights the completed, and ongoing clinical trials of COVID-19 vaccines and efforts are being made globally to avert the pandemic.

Insights into the immune responses of SARS-CoV-2 in relation to COVID-19 vaccines

The three types of approved coronavirus disease 2019 (COVID-19) vaccines that have been emergency-use listed (EUL) by the World Health Organization are mRNA vaccines, adenovirus-vectored vaccines, and inactivated vaccines. Canonical vaccine developments usually take years or decades to be completed to commercialization; however, the EUL vaccines being used in the current situation comprise several COVID-19 vaccine candidates applied in studies and clinical settings across the world. The extraordinary circumstances of the COVID-19 pandemic have necessitated the emergency authorization of these EUL vaccines, which have been rapidly developed. Although the benefits of the EUL vaccines outweigh their adverse effects, there have been reports of rare but fatal cases directly associated with COVID-19 vaccinations. Thus, a reassessment of the immunological rationale underlying EUL vaccines in relation to COVID-19 caused by SARSCOV-2 virus infection is now required. In this review, we discuss the manifestations of COVID-19, immunologically projected effects of EUL vaccines, reported immune responses, informed issues related to COVID-19 vaccination, and the potential strategies for future vaccine use against antigenic variants.

A Novel Bacterial Protease Inhibitor Adjuvant in RBD-Based COVID-19 Vaccine Formulations Containing Alum Increases Neutralizing Antibodies, Specific Germinal Center B Cells and Confers Protection Against SARS-CoV-2 Infection in Mice

In this work, we evaluated recombinant receptor binding domain (RBD)-based vaccine formulation prototypes with potential for further clinical development. We assessed different formulations containing RBD plus alum, AddaS03, AddaVax, or the combination of alum and U-Omp19: a novel Brucella spp. protease inhibitor vaccine adjuvant. Results show that the vaccine formulation composed of U-Omp19 and alum as adjuvants has a better performance: it significantly increased mucosal and systemic neutralizing antibodies in comparison to antigen plus alum, AddaVax, or AddaS03. Antibodies induced with the formulation containing U-Omp19 and alum not only increased their neutralization capacity against the ancestral virus but also cross-neutralized alpha, lambda, and gamma variants with similar potency. Furthermore, the addition of U-Omp19 to alum vaccine formulation increased the frequency of RBD-specific geminal center B cells and plasmablasts. Additionally, U-Omp19+alum formulation induced RBD-specific Th1 and CD8⁺ T-cell responses in spleens and lungs. Finally, this vaccine formulation conferred protection against an intranasal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) challenge of K18-hACE2 mice.

The Analogs of Furanyl Methylidene Rhodanine Exhibit Broad-Spectrum Inhibitory and Inactivating Activities against Enveloped Viruses, including SARS-CoV-2 and Its Variants

In recent years, infectious diseases caused by viral infections have seriously endangered human health, especially COVID-19, caused by SARS-CoV-2, which continues to spread worldwide. The development of broad-spectrum antiviral inhibitors is urgently needed. Here, we report a series of small-molecule compounds that proved effective against human coronaviruses (HCoV), such as SARS-CoV-2 and its variants of concern (VOCs), including Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B.1.1.529), SARS-CoV, MERS-CoV, HCoV-OC43, and other viruses with class I viral fusion proteins, such as influenza virus, Ebola virus (EBOV), Nipah virus (NiV), and Lassa fever virus (LASV). They are also effective against class II enveloped viruses represented by ZIKV and class III enveloped viruses represented by vesicular stomatitis virus (VSV). Further studies have shown that these compounds may exert antiviral effects through a variety of mechanisms, including inhibiting the formation of the six-helix bundle, which is a typical feature of enveloped virus fusion with cell membranes, and/or targeting viral membrane to inactivate cell-free virions. These compounds are expected to become drug candidates against SARS-CoV-2 and other enveloped viruses.

Mesenchymal stem cell-based treatments for COVID-19: status and future perspectives for clinical applications

As a result of cross-species transmission in December 2019, the coronavirus disease 2019 (COVID-19) became a serious endangerment to human health and the causal agent of a global pandemic. Although the number of infected people has decreased due to effective management, novel methods to treat critical COVID-19 patients are still urgently required. This review describes the origins, pathogenesis, and clinical features of COVID-19 and the potential uses of mesenchymal stem cells (MSCs) in therapeutic treatments for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected patients. MSCs have previously been shown to have positive effects in the treatment of lung diseases, such as acute lung injury, idiopathic pulmonary fibrosis, acute respiratory distress syndrome, lung cancer, asthma, and chronic obstructive pulmonary disease. MSC mechanisms of action involve differentiation potentials, immune regulation, secretion of anti-inflammatory factors, migration and homing, anti-apoptotic properties, antiviral effects, and extracellular vesicles. Currently, 74 clinical trials are investigating the use of MSCs (predominately from the umbilical cord, bone marrow, and adipose tissue) to treat COVID-19. Although most of these trials are still in their early stages, the preliminary data are promising. However, long-term safety evaluations are still lacking, and large-scale and controlled trials are required for more conclusive judgments regarding MSC-based therapies. The main challenges and prospective directions for the use of MSCs in clinical applications are discussed herein. In summary, while the clinical use of MSCs to treat COVID-19 is still in the preliminary stages of investigation, promising results indicate that they could potentially be utilized in future treatments.

A SARS-CoV-2 ferritin nanoparticle vaccine elicits protective immune responses in nonhuman primates

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants stresses the continued need for next-generation vaccines that confer broad protection against coronavirus disease 2019 (COVID-19). We developed and evaluated an adjuvanted SARS-CoV-2 spike ferritin nanoparticle (SpFN) vaccine in nonhuman primates. High-dose (50 μg) SpFN vaccine, given twice 28 days apart, induced a Th1-biased CD4 T cell helper response and elicited neutralizing antibodies against SARS-CoV-2 wild-type and variants of concern, as well as against SARS-CoV-1. These potent humoral and cell-mediated immune responses translated into rapid elimination of replicating virus in the upper and lower airways and lung parenchyma of nonhuman primates following high-dose SARS-CoV-2 respiratory challenge. The immune response elicited by SpFN vaccination and resulting efficacy in nonhuman primates supports the utility of SpFN as a vaccine candidate for SARS-causing betacoronaviruses.

Immunization with synthetic SARS-CoV-2 S glycoprotein virus-like particles protects macaques from infection

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has caused an ongoing global health crisis. Here, we present as a vaccine candidate synthetic SARS-CoV-2 spike (S) glycoprotein-coated lipid vesicles that resemble virus-like particles. Soluble S glycoprotein trimer stabilization by formaldehyde cross-linking introduces two major inter-protomer cross-links that keep all receptor-binding domains in the “down” conformation. Immunization of cynomolgus macaques with S coated onto lipid vesicles (S-LVs) induces high antibody titers with potent neutralizing activity against the vaccine strain, Alpha, Beta, and Gamma variants as well as T helper (Th)1 CD4⁺-biased T cell responses. Although anti-receptor-binding domain (RBD)-specific antibody responses are initially predominant, the third immunization boosts significant non-RBD antibody titers. Challenging vaccinated animals with SARS-CoV-2 shows a complete protection through sterilizing immunity, which correlates with the presence of nasopharyngeal anti-S immunoglobulin G (IgG) and IgA titers. Thus, the S-LV approach is an efficient and safe vaccine candidate based on a proven classical approach for further development and clinical testing.

•

S glycoprotein formaldehyde cross-linking stabilizes S in the prefusion conformation

•

Vaccination of cynomolgus macaques with S lipid particles induces neutralization

•

Vaccination protects macaques against a SARS-CoV-2 challenge

•

Sterilizing protection correlates with nasopharyngeal anti-S IgG and IgA titers

A Battle against COVID-19: Vaccine Hesitancy and Awareness with a Comparative Study between Sinopharm and AstraZeneca

Background: Awareness about the COVID-19 vaccine’s adverse effects is crucial for gaining public trust. As we still lack proof of vaccines’ safety, this survey aimed to investigate Egyptians’ general awareness of the Sinopharm and AstraZeneca vaccines against COVID-19 and provide considerable evidence on their side effects and complications. Methods: A cross-sectional questionnaire-based study was conducted in Egypt between 20 September and 10 October in 2021, with multiple-choice questions (MCQs) covering all data on vaccine administration confusion, adverse effects or intensity, and complications. Results: Among the 390 participants, 42.3% reported being hesitant before receiving one of the vaccines. About 40.3% of participants were previously infected before getting vaccinated while only 4.6% reported being infected after vaccination. The AstraZeneca vaccine demonstrated higher side effects and symptoms than the Sinopharm vaccine while the Sinopharm vaccine showed a significantly higher rate of COVID-19 infection after vaccination. Conclusions: People with higher educational levels and chronic respiratory diseases represent an excellent model for accepting COVID-19 vaccination. A booster shot is recommended for people vaccinated with the Sinopharm vaccine due to a significantly higher rate of COVID-19 infection after vaccination; however, the Sinopharm vaccine shows a more acceptable safety profile.

Rare-earth ions as antibacterial agents for woven wool fabric

Woven fabrics were bestowed with antibacterial property by the simple adsorption of rare-earth metal ions, and the underlying mechanism was investigated using electron spin resonance (ESR) spectroscopy. The adsorption of Ce³⁺ ions on wool, silk, and cotton fabrics resulted in significant inhibition of Staphylococcus aureus (a gram-positive bacterium), with maximum antibacterial activities (viable bacterial count compared to the reference) of 4.7, 5.8, and 5.2, respectively. Even after 50 wash cycles, the values remained at 3.9, 2.9, and 4.8, respectively. The adsorption of La³⁺ and Gd³⁺ ions on wool fabrics also resulted in antibacterial activities of 5.8 and 5.9, respectively. In addition, wool adsorbed with Ce³⁺ exhibits a satisfactory antibacterial activity of 6.2 against Escherichia coli (a gram-negative bacterium). Such bacterial inhibition is attributed to Fenton reactions between the adsorbed rare-earth ions and hydrogen peroxide (H₂O₂) produced during bacterial metabolism, as determined from the ESR spectra collected using the spin trap method in the presence of H₂O₂. The safety of cerium nitrate was also investigated, and no significant issues arose, indicating that it was a safe antibacterial agent. This facile method of imparting antibacterial properties to natural fabrics may be useful for preventing infections in humans.

The Complexity of SARS-CoV-2 Infection and the COVID-19 Pandemic

The pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to the death of millions of people worldwide and thousands more infected individuals developed sequelae due to the disease of the new coronavirus of 2019 (COVID-19). The development of several studies has contributed to the knowledge about the evolution of SARS-CoV2 infection and the disease to more severe forms. Despite this information being debated in the scientific literature, many mechanisms still need to be better understood in order to control the spread of the virus and treat clinical cases of COVID-19. In this article, we carried out an extensive literature review in order to bring together, in a single article, the biological, social, genetic, diagnostic, therapeutic, immunization, and even socioeconomic aspects that impact the SAR-CoV-2 pandemic. This information gathered in this article will enable a broad and consistent reading of the main aspects related to the current pandemic.

Insight into the Advances in Clinical Trials of SARS-CoV-2 Vaccines

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has thrown a challenge to the scientific community. Several interventions to stop or limit the spread of infection have failed, and every time the virus emerges, it becomes more contagious and more deadly. Vaccinating a significant proportion of the population is one of the established methods to achieve herd immunity. More than 100 COVID-19 vaccines have been designed and tested against the virus. The development of a new vaccine takes years of testing, but due to the pandemic, healthcare authorities have given emergency use authorization for a few vaccines. Among them are BioNTech and Moderna vaccines (mRNA based); ChAdOx1, Gam-COVID-Vac, Janssen vaccines (vector-based); CoronaVac, COVAXIN (virus inactivated); and EpiVacCorona vaccine (viral peptide). Mixtures of vaccines are also being tested to evaluate their efficacy against mutant strains of SARS-CoV-2. All these vaccines in clinical trials have shown robust production of neutralizing antibodies sufficient to prevent infection. Some of the vaccinated people reported serious complications. However, no definitive relationship could be established between vaccination administration and the occurrence of these complications. None of the COVID-19 vaccines approved to date have been found to be effective against all of the SARS-CoV-2 variants.

Immunology and Technology of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Vaccines

We have experienced an enormous cohesive effort of the scientific community to understand how the immune system reacts to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and how to elicit protective immunity via vaccination. This effort resulted in the development of vaccines in record time with high levels of safety, efficacy, and real-life effectiveness. However, the rapid diffusion of viral variants that escape protective antibodies prompted new studies to understand SARS-CoV-2 vulnerabilities and strategies to guide follow-up actions to increase, and maintain, the protection offered by vaccines. In this review, we report the main findings on human immunity to SARS-CoV-2 after natural infection and vaccination; we dissect the immunogenicity and efficacy of the different vaccination strategies that resulted in products widely used in the population; and we describe the impact of viral variants on vaccine-elicited immunity, summarizing the main discoveries and challenges to stay ahead of SARS-CoV-2 evolution. SIGNIFICANCE STATEMENT: This study reviewed findings on human immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), analyzed the immunogenicity and efficacy of the various vaccines currently used in large vaccination campaigns or candidates in advanced clinical development, and discussed the challenging task to ensure high protective efficacy against the rapidly evolving SARS-CoV-2 virus. This manuscript was completed prior to the emergence of the Omicron variant and to global vaccine boosting efforts.

Impact of the Sinopharm’s BBIBP-CorV vaccine in preventing hospital admissions and death in infected vaccinees: Results from a retrospective study in the emirate of Abu Dhabi, United Arab Emirates (UAE)

Background

This is a community-based, retrospective, observational study conducted to determine effectiveness of the BBIBP-CorV inactivated vaccine in the real-world setting against hospital admissions and death.

Study Design

Study participants were selected from 214,940 PCR-positive cases of COVID-19 reported to the Department of Health, Abu Dhabi Emirate, United Arab Emirates (UAE) between September 01, 2020 and May 1, 2021. Of these, 176,640 individuals were included in the study who were aged ≥ 15 years with confirmed COVID-19 positive status who had records linked to their vaccination status. Those with incomplete or missing records were excluded (n = 38,300). Study participants were divided into three groups depending upon their vaccination status: fully vaccinated (two doses), partially vaccinated (single dose), and non-vaccinated. Study outcomes included COVID-19-related admissions to hospital general and critical care wards and death. Vaccine effectiveness for each outcome was based on the incidence density per 1000 person-years.

Results

The fully-, partially- and non-vaccinated groups included 62,931, 21,768 and 91,941 individuals, respectively. Based on the incidence rate ratios, the vaccine effectiveness in fully vaccinated individuals was 80%, 92%, and 97% in preventing COVID-19-related hospital admissions, critical care admissions, and death, respectively, when compared to the non-vaccinated group. No protection was observed for critical and non-critical care hospital admissions for the partially vaccinated group, while some protection against death was apparent, although statistically insignificant.

Conclusions

In a COVID-19 pandemic, use of the Sinopharm BBIBP-CorV inactivated vaccine is effective in preventing severe disease and death in a two-dose regimen. Lack of protection with the single dose may be explained by insufficient seroconversion and/or neutralizing antibody responses, behavioral factors (i.e., false sense of protection), and/or other biological factors (emergence of variants, possibility of reinfection, duration of vaccine protection, etc.).

Phage Display-Derived Peptide for the Specific Binding of SARS-CoV-2

Beginning from the end of 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic swept all over the world and is still afflicting the whole global population. Given that the vaccine-manufacturing ability is limited and the virus can evolve quickly, vaccination alone may not be able to end the pandemic, thus developing fast and accurate diagnoses and effective therapeutics will always be unmet needs. Phage display peptide library has been used in screening antigen-specific peptides for the invention of novel mimic receptors/ligands. Here, we report that a 12-mer phage display peptide library has been screened against the SARS-CoV-2 receptor-binding domain (RBD), and five of the screened peptides show binding ability with the RBD protein by the enzyme-linked immune sorbent assay. The surface plasmon resonance assay further demonstrates that peptide no. 1 can specifically bind to SARS-CoV-2 RBD with a binding affinity constant (K d) of 5.8 μM. Transmission electron microscopy coupled with a magnetic bead assay further confirms that the screened peptide can specifically bind the inactivated SARS-CoV-2 virus. This SARS-CoV-2-specific peptide holds great promise as a new bioreceptor/ligand for the rapid and accurate detection of SARS-CoV-2.

Application of pseudovirus system in the development of vaccine, antiviral-drugs, and neutralizing antibodies

Pseudoviruses are viral particles coated with a heterologous envelope protein, which mediates the entry of pseudoviruses as efficiently as that of the live viruses possessing high pathogenicity and infectivity. Due to the deletion of the envelope protein gene and the absence of pathogenic genes, pseudoviruses have no autonomous replication ability and can infect host cells for only a single cycle. In addition, pseudoviruses have the desired characteristics of high safety, strong operability, and can be easily used to perform rapid throughput detection. Therefore, pseudoviruses are widely employed in the mechanistic investigation of viral infection, the screening and evaluation of monoclonal antibodies and antiviral drugs, and the detection of neutralizing antibody titers in serum after vaccination. In this review, we will discuss the construction of pseudoviruses based on different packaging systems, their current applications especially in the research of SARS-CoV-2, limitations, and further directions.

Exploring Rapid and Effective Screening Methods for Anti-SARS-CoV-2 Neutralizing Antibodies in COVID-19 Convalescent Patients and Longitudinal Vaccinated Populations

Assessing the duration of neutralizing antibodies (nAbs) following SARS-CoV-2 infection or vaccination is critical to evaluate the protective immunity and formulate public health strategies. In this study, SARS-CoV-2 Ab ELISA (enzyme-linked immunosorbent assay), chemiluminescent microparticle immunoassay (CMIA), as well as pseudovirus neutralization test (PVNT) were performed in two cohorts, convalescent patients (CP) from coronavirus disease 2019 (COVID-19) and BBIBP-CorV vaccinated population. It was found that nAbs and binding antibodies emerged at 14 days post the 1st dose of vaccination, reached peaks at 28 days after 2nd dose vaccination and then gradually declined over time. CP-6M (convalescent patients up to 6 months) from COVID-19 presented stronger nAbs or binding antibodies responses than vaccinees 90 days or 180 days after 2nd dose vaccination. CMIA or SARS-CoV-2 Ab ELISA correlated well with PVNT with high consistency in the two cohorts. It shown that nAbs and binding antibodies can keep 6 months both in CP and vaccinees. Most importantly, our data show the application of using CMIA and SARS-CoV-2 Ab ELISA as rapid screening tests for nAb titer and could be used as alternative strategies for quickly evaluating SARS-CoV-2 nAbs responses in vaccine research.

Review on Approved and Inprogress COVID-19 Vaccines

The last generation of Coronavirus named COVID-19 is responsible for the recent worldwide outbreak. Concerning the widespread and quick predominance, there is a critical requirement for designing appropriate vaccines to surmount this grave problem. Correspondingly, in this revision, COVID-19 vaccines (which are being developed until March 29th, 2021) are classified into specific and non-specific categories. Specific vaccines comprise genetic-based vaccines (mRNA, DNA), vector-based, protein/recombinant protein vaccines, inactivated viruses, live-attenuated vaccines, and novel strategies including microneedle arrays (MNAs), and nanoparticles vaccines. Moreover, specific vaccines such as BCG, MRR, and a few other vaccines are considered Non-specific. What is more, according to the significance of Bioinformatic sciences in the cutting-edge vaccine design and rapid outbreak of COVID-19, herein, Bioinformatic principles including reverse vaccinology, epitopes prediction/selection and, their further applications in the design of vaccines are discussed. Last but not least, safety, challenges, advantages, and future prospects of COVID-19 vaccines are highlighted.

A novel STING agonist-adjuvanted pan-sarbecovirus vaccine elicits potent and durable neutralizing antibody and T cell responses in mice, rabbits and NHPs

The emergence of SARS-CoV-2 variants and potentially other highly pathogenic sarbecoviruses in the future highlights the need for pan-sarbecovirus vaccines. Here, we discovered a new STING agonist, CF501, and found that CF501-adjuvanted RBD-Fc vaccine (CF501/RBD-Fc) elicited significantly stronger neutralizing antibody (nAb) and T cell responses than Alum- and cGAMP-adjuvanted RBD-Fc in mice. Vaccination of rabbits and rhesus macaques (nonhuman primates, NHPs) with CF501/RBD-Fc elicited exceptionally potent nAb responses against SARS-CoV-2 and its nine variants and 41 S-mutants, SARS-CoV and bat SARSr-CoVs. CF501/RBD-Fc-immunized hACE2-transgenic mice were almost completely protected against SARS-CoV-2 challenge, even 6 months after the initial immunization. NHPs immunized with a single dose of CF501/RBD-Fc produced high titers of nAbs. The immunized macaques also exhibited durable humoral and cellular immune responses and showed remarkably reduced viral load in the upper and lower airways upon SARS-CoV-2 challenge even at 108 days post the final immunization. Thus, CF501/RBD-Fc can be further developed as a novel pan-sarbecovirus vaccine to combat current and future outbreaks of sarbecovirus diseases.

The Variation of SARS-CoV-2 and Advanced Research on Current Vaccines

Over the past 2 years, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the coronavirus disease 2019 (COVID-19) and rapidly spread worldwide. In the process of evolution, new mutations of SARS-CoV-2 began to appear to be more adaptable to the diverse changes of various cellular environments and hosts. Generally, the emerging SARS-CoV-2 variants are characterized by high infectivity, augmented virulence, and fast transmissibility, posing a serious threat to the prevention and control of the global epidemic. At present, there is a paucity of effective measurements to cure COVID-19. It is extremely crucial to develop vaccines against SARS-CoV-2 and emerging variants to enhance individual immunity, but it is not yet known whether they are approved by the authority. Therefore, we systematically reviewed the main characteristics of the emerging various variants of SARS-CoV-2, including their distribution, mutations, transmissibility, severity, and susceptibility to immune responses, especially the Delta variant and the new emerging Omicron variant. Furthermore, we overviewed the suitable crowd, the efficacy, and adverse events (AEs) of current vaccines.

Plant-Based Vaccines in Combat against Coronavirus Diseases

Coronavirus (CoV) diseases, including Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS) have gained in importance worldwide, especially with the current COVID-19 pandemic caused by SARS-CoV-2. Due to the huge global demand, various types of vaccines have been developed, such as more traditional attenuated or inactivated viruses, subunit and VLP-based vaccines, as well as novel DNA and RNA vaccines. Nonetheless, emerging new COVID-19 variants are necessitating continuous research on vaccines, including these produced in plants, either via stable expression in transgenic or transplastomic plants or transient expression using viral vectors or agroinfection. Plant systems provide low cost, high scalability, safety and capacity to produce multimeric or glycosylated proteins. To date, from among CoVs antigens, spike and capsid proteins have been produced in plants, mostly using transient expression systems, at the additional advantage of rapid production. Immunogenicity of plant-produced CoVs proteins was positively evaluated after injection of purified antigens. However, this review indicates that plant-produced CoVs proteins or their carrier-fused immunodominant epitopes can be potentially applied also as mucosal vaccines, either after purification to be administered to particular membranes (nasal, bronchus mucosa) associated with the respiratory system, or as oral vaccines obtained from partly processed plant tissue.

Modelling the DFT structural and reactivity study of feverfew and evaluation of its potential antiviral activity against COVID-19 using molecular docking and MD simulations

Abstract

The unavailability of a proper drug against SARS-CoV-2 infections and the emergence of various variants created a global crisis. In the present work, we have studied the antiviral behavior of feverfew plant in treating COVID-19. We have reported a systematic in silico study with the antiviral effects of various phytoconstituents Borneol (C₁₀H₁₈O), Camphene (C₁₀H₁₆), Camphor (C₁₀H₁₆O), Alpha-thujene (C₁₀H₁₆), Eugenol (C₁₀H₁₄O), Carvacrol (C₁₀H₁₄O) and Parthenolide (C₁₅H₂₀O₃) of feverfew on the viral protein of SARS-CoV-2. Parthenolide shows the best binding affinity with both main protease (M^pro) and papain-like protease (PL^pro). The molecular electrostatic potential and Mulliken atomic charges of the Parthenolide molecule shows the high chemical reactivity of the molecule. The docking of Parthenolide with PL^pro give score of −8.0 kcal/mol that validates the good binding of Parthenolide molecule with PL^pro. This complex was further considered for molecular dynamics simulations. The binding energy of the complex seems to range in between −3.85 to −11.07 kcal/mol that is high enough to validate the stability of the complex. Free energy decomposition analysis have been also performed to understand the contribution of residues that reside into the binding site. Good binding affinity and reactivity response suggested that Parthenolide can be used as a promising drug against the COVID-19.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11696-022-02067-6.

Booster vaccination strategy: Necessity, Immunization Objectives, Immunization Strategy and Safety

At present, the global COVID-19 epidemic has not been completely controlled, and epidemic prevention and control still face severe challenges. As there is no specific treatment for COVID-19, promoting roll-out vaccinations and building herd immunity are still the most effective and economic measures to control the COVID-19 pandemic. However, the neutralizing antibody level in the recipients decreases with time, and the vaccine's protective efficacy gradually weakens. It is still inconclusive whether it is necessary to carry out booster vaccination to strengthen the immune barrier to infection. In this paper, we combined the existing data on the effectiveness and persistence of COVID-19 vaccines. We found that it is necessary to carry out a booster vaccination strategy. However, not all subjects need to receive one more dose of vaccine six months after the initial immunization. Priority should be given to the high-risk groups, such as the elderly and people with immunodeficiency. A heterologous booster can induce higher immune responses and enhance immune protection than homologous vaccinations. However, more scientific data and clinical studies are needed to verify the safety of heterologous vaccination strategies. This article is protected by copyright. All rights reserved.

Characterization of SARS-CoV-2-Specific Humoral and Cellular Immune Responses Induced by Inactivated COVID-19 Vaccines in a Real-World Setting

While the immunogenicity of inactivated vaccines against coronavirus disease 2019 (COVID-19) has been characterized in several well-conducted clinical trials, real-world evidence concerning immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) raised by such vaccines is currently missing. Here, we comprehensively characterized various parameters of SARS-CoV-2-specific cellular and humoral immune responses induced by inactivated COVID-19 vaccines in 126 individuals under real-world conditions. After two doses of vaccination, S-receptor binding domain IgG (S-RBD IgG) and neutralizing antibody (NAb) were detected in 87.06% (74/85) and 78.82% (67/85) of individuals, respectively. Female participants developed higher concentrations of S-RBD IgG and NAb compared to male vaccinees. Interestingly, a longer dosing interval between the first and second vaccination resulted in a better long-term SARS-CoV-2 S-RBD IgG response. The frequencies of CD4+ T cells that produce effector cytokines (IFN-γ, IL-2, and TNF-α) in response to stimulation with peptide pools corresponding to the SARS-CoV-2 spike (S), nucleocapsid (N) or membrane (M) protein were significantly higher in individuals received two doses of vaccine than those received one dose of vaccine and unvaccinated individuals. S, N, or M-specific CD4+ and CD8+ T cell responses were detectable in 95.83% (69/72) and 54.16% (39/72) of double-vaccinated individuals, respectively. The longitudinal analysis demonstrated that CD4+ T cell responses recognizing S, N, and M waned quickly after a single vaccine dose, but were boosted and became more sustained following a second dose. Overall, we provide a comprehensive characterization of immune responses induced by inactivated COVID-19 vaccines in real-world settings, suggesting that both humoral and cellular SARS-CoV-2-specific immunity are elicited in the majority of individuals after two doses of inactivated COVID-19 vaccines.