Platforms Exploited for SARS-CoV-2 Vaccine Development

Development, Pre-Clinical Safety, and Immune Profile of RENOVAC-A Dimer RBD-Based Anti-Coronavirus Subunit Vaccine

Background: The development of effective and safe vaccines and their timely delivery to the public play a crucial role in preventing and managing infectious diseases. Many vaccines have been produced and distributed globally to prevent COVID-19 infection. However, establishing effective vaccine development platforms and evaluating their safety and immunogenicity remains critical to increasing health security, especially in developing countries. Objectives: Therefore, we developed a local subunit vaccine candidate, RENOVAC, and reported its toxicity and immunogenicity profile in animal models. Methods: First, the synthetic gene-coding tandem RBD linked with the GS linker was cloned into the expression vector and expressed in CHO cells. The protein was then purified and filter sterilized, and 10 µg/dose and 25 µg/dose formulations were finally examined for the 14-day repeated dose toxicity followed by the immunogenic profile in preclinical studies. Results: When administered to Sprague Dawley rats by intramuscular route, the vaccine was well tolerated up to and including the dose of 25 µg/animal, and no toxicologically adverse changes were noted. The observed change in weight of the thymus and spleen might be related to the immunological response to the vaccine. The dimer RBD vaccine demonstrated the ability to generate high levels of specific immunoglobulins (IGs) and neutralization antibodies (NAbs). Finally, changes in the amounts of specific T cells and cytokines after vaccination suggested that the vaccine mainly triggers an immune response by activating CD4+ Th2-cells, which then activate B-cells to provide humoral immunity. Conclusions: The study suggests that, based on its reliable immunogenicity and acceptable safety, the vaccine can be further directed for clinical trials.

Multi-antigen intranasal vaccine protects against challenge with sarbecoviruses and prevents transmission in hamsters

Immunization programs against SARS-CoV-2 with commercial intramuscular vaccines prevent disease but are less efficient in preventing infections. Mucosal vaccines can provide improved protection against transmission, ideally for different variants of concern (VOCs) and related sarbecoviruses. Here, we report a multi-antigen, intranasal vaccine, NanoSTING-SN (NanoSTING-Spike-Nucleocapsid), eliminates virus replication in both the lungs and the nostrils upon challenge with the pathogenic SARS-CoV-2 Delta VOC. We further demonstrate that NanoSTING-SN prevents transmission of the SARS-CoV-2 Omicron VOC (BA.5) to vaccine-naïve hamsters. To evaluate protection against other sarbecoviruses, we immunized mice with NanoSTING-SN. We showed that immunization affords protection against SARS-CoV, leading to protection from weight loss and 100% survival in mice. In non-human primates, animals immunized with NanoSTING-SN show durable serum IgG responses (6 months) and nasal wash IgA responses cross-reactive to SARS-CoV-2 (XBB1.5), SARS-CoV and MERS-CoV antigens. These observations have two implications: (1) mucosal multi-antigen vaccines present a pathway to reducing transmission of respiratory viruses, and (2) eliciting immunity against multiple antigens can be advantageous in engineering pan-sarbecovirus vaccines.

Innovative Strategies to Enhance mRNA Vaccine Delivery and Effectiveness: Mechanisms and Future Outlook

The creation of mRNA vaccines has transformed the area of vaccination and allowed for the production of COVID-19 vaccines with previously unheard-of speed and effectiveness. The development of novel strategies to enhance the delivery and efficiency of mRNA vaccines has been motivated by the ongoing constraints of the present mRNA vaccine delivery systems. In this context, intriguing methods to get beyond these restrictions include lipid nanoparticles, self-amplifying RNA, electroporation, microneedles, and cell-targeted administration. These innovative methods could increase the effectiveness, safety, and use of mRNA vaccines, making them more efficient, effective, and broadly available. Additionally, mRNA technology may have numerous and far-reaching uses in the field of medicine, opening up fresh avenues for the diagnosis and treatment of disease. This paper gives an overview of the existing drawbacks of mRNA vaccine delivery techniques, the creative solutions created to address these drawbacks, and their prospective public health implications. The development of mRNA vaccines for illnesses other than infectious diseases and creating scalable and affordable manufacturing processes are some of the future directions for research in this area that are covered in this paper.

Humoral responses to the CoronoVac vaccine in healthcare workers

BACKGROUND

This study aimed to assess the immunoglobulin G (IgG) antibody response rate in emergency department (ED) healthcare workers (HCWs) and potential adverse effects after CoronaVac vaccination.

METHODS

All included HCWs were grouped based on the previous history of coronavirus disease 2019 (COVID-19) and the number of vaccinations. Furthermore, the IgG antibody response was evaluated based on the sex and smoking status of HCWs. Those with a cut-off index of ≥1.00 after vaccination with CoronaVac were considered to have had COVID-19 and had an adequate humoral response.

RESULTS

Among 224 ED HCWs, 18% experienced the adverse effects of CoronaVac vaccine, the most prevalent being pain in the injection site. The IgG antibody response rate was 20% after the first dose of vaccine, while the response rate increased to 90% after the second dose. Female HCWs had higher IgG response rates compared with male HCWs (53.8 [15.9-147.0] vs 31.2 [4.5-124.0]). Non-smokers had higher IgG response rate compared with smokers (49.0 [11.5-160.5] vs 23.1 [7.4-98.5]).

CONCLUSION

A single dose of CoronaVac does not produce a sufficient antibody response; hence, two doses are recommended. Men have a lower IgG response compared with women. Smokers had a lower IgG response rate compared with non-smokers. Therefore, it may be necessary to carefully assess the humoral responses of men and smokers when implementing a community vaccination program.

COVID-19 vaccines adverse events: potential molecular mechanisms

COVID-19 is an infectious disease caused by a single-stranded RNA (ssRNA) virus, known as SARS-CoV-2. The disease, since its first outbreak in Wuhan, China, in December 2019, has led to a global pandemic. The pharmaceutical industry has developed several vaccines, of different vector technologies, against the virus. Of note, among these vaccines, seven have been fully approved by WHO. However, despite the benefits of COVID-19 vaccination, some rare adverse effects have been reported and have been associated with the use of the vaccines developed against SARS-CoV-2, especially those based on mRNA and non-replicating viral vector technology. Rare adverse events reported include allergic and anaphylactic reactions, thrombosis and thrombocytopenia, myocarditis, Bell's palsy, transient myelitis, Guillen-Barre syndrome, recurrences of herpes-zoster, autoimmunity flares, epilepsy, and tachycardia. In this review, we discuss the potential molecular mechanisms leading to these rare adverse events of interest and we also attempt an association with the various vaccine components and platforms. A better understanding of the underlying mechanisms, according to which the vaccines cause side effects, in conjunction with the identification of the vaccine components and/or platforms that are responsible for these reactions, in terms of pharmacovigilance, could probably enable the improvement of future vaccines against COVID-19 and/or even other pathological conditions.

Mother’s Pregnancy Trimester Does Not Affect the Differences of IgG SARS-COV-2 Antibody Levels in Pregnant Women after mRNA and Inactivated Coronavirus Disease 2019 Vaccination

BACKGROUND: Since pregnancy increases the risk of coronavirus disease 2019 (COVID-19) and its morbidity in pregnant women, it is necessary and recommended to prevent COVID-19 in pregnant women by vaccination such as by messenger RNA (mRNA) and inactivated vaccines. SARS-CoV-2 antibodies produced from vaccination have different results according to the type of vaccine given. The previous studies showed that IgG SARS-CoV-2 antibody levels were influenced by various factors such as gestational weeks at the time when vaccines were given. Moreover, there have been no previous studies on the effect of gestational age on quantitative IgG levels after the second dose of the vaccine especially in Indonesia during this pandemic due to some restrictions on daily activities. AIM: The aim of this study is to see the effect of giving the COVID-19 vaccine based on maternal gestational age (in trimester units) on maternal immunity (IgG SARS-CoV-2) in Dr. Hasan Sadikin General Hospital Bandung, Bandung Kiwari Hospital and Dr. Slamet Hospital, Garut. METHODS: This was a retrospective and cohort study by taking secondary data using consecutive sampling from the previous tests on the levels of SARS-CoV-2 IgG antibodies after two doses of inactivated vaccine and mRNA. Healthy pregnant women 14–34 weeks at the Department of Obstetrics and Gynecology, Dr. Hasan Sadikin (RSHS) Bandung, Bandung Kiwari Hospital, and Dr. Slamet Hospital for the period October 2021 to January 2022 were the target population of this study. Based on inclusion and exclusion criteria, 103 samples met the criteria. Examination of Maternal SARS-CoV-2 IgG Antibody Levels procedures was carried out using Chemiluminescent Microparticle Immunoassay. Statistical analysis was done using IBM SPSS 28.00 and p < 0.05 was considered statistically significant. RESULTS: There was no significant difference (p = 0.236, p > 0.05) between the mean maternal age in the mRNA and inactivated vaccine groups. The mRNA and inactivated vaccine groups also had no significant difference in the gestational age category (0.70). There was a significant difference (p = 0.0001) between the levels of SARS-CoV-2 IgG antibodies after the vaccine in the mRNA and inactivated vaccine groups. There was no significant difference in the levels of SARS-CoV-2 IgG antibodies in the gestational age group after the mRNA vaccine (p = 0.426) and after the inactivated vaccine (p = 0.293). There was a significant difference (p < 0.05) in the subgroup analysis in each gestational age group (second trimester and third trimester) between SARS-CoV-2 IgG antibody levels after the mRNA vaccine compared to inactivated vaccine. DISCUSSIONS: The mRNA vaccine is based on the principle that mRNA is an intermediate messenger to be translated to an antigen after delivery to the host cell via various routes. However, inactivated vaccines contain viruses whose genetic material has been destroyed by heat, chemicals, or radiation, so they cannot infect cells and replicate but can still trigger an immune response. The administration of the vaccine in the second and third trimesters of pregnancy has the same results in increasing levels of SARS-CoV-2 IgG antibodies after mRNA and inactivated vaccination in this study. CONCLUSIONS: mRNA vaccination in pregnant women is better than inactivated vaccines based on the levels of IgG SARS-CoV-2 antibodies after vaccination. The maternal trimester of pregnancy was not a factor influencing the levels of SARS-CoV-2 IgG antibodies after either mRNA or inactivated COVID-19 vaccinations in this study.

A comparison between SARS-CoV-1 and SARS-CoV2: an update on current COVID-19 vaccines

Since the outbreak of the novel coronavirus disease 2019 (COVID-19) in Wuhan, China, many health care systems have been heavily engaged in treating and preventing the disease, and the year 2020 may be called as "historic COVID-19 vaccine breakthrough". Due to the COVID-19 pandemic, many companies have initiated investigations on developing an efficient and safe vaccine against the virus. From Moderna and Pfizer in the United States to PastocoVac in Pasteur Institute of Iran and the University of Oxford in the United Kingdom, different candidates have been introduced to the market. COVID-19 vaccine research has been facilitated based on genome and structural information, bioinformatics predictions, epitope mapping, and data obtained from the previous developments of severe acute respiratory syndrome coronavirus (SARS-CoV or SARS-CoV-1) and middle east respiratory syndrome coronavirus (MERS-CoV) vaccine candidates. SARS-CoV genome sequence is highly homologous to the one in COVID-19 and both viruses use the same receptor, angiotensin-converting enzyme 2 (ACE2). Moreover, the immune system responds to these viruses, partially in the same way. Considering the on-going COVID-19 pandemic and previous attempts to manufacture SARS-CoV vaccines, this paper is going to discuss clinical cases as well as vaccine challenges, including those related to infrastructures, transportation, possible adverse reactions, utilized delivery systems (e.g., nanotechnology and electroporation) and probable vaccine-induced mutations.

The Race for COVID-19 Vaccines: The Various Types and Their Strengths and Weaknesses

SARS-CoV-2 causes the highly contagious coronavirus disease (COVID-19), first discovered in Wuhan, China, in December of 2019. As of August 21, 2021, over 211 million people have been diagnosed with COVID-19 and 4.42 million people have died from the disease worldwide. The COVID-19 pandemic has adversely affected world economies, global public health infrastructure, and social behaviors. Despite physical distancing and the advent of symptomatic and monoclonal antibody therapies, perhaps the most effective method to combat COVID-19 remains the creation of immunity through vaccines. Scientific communities globally have been diligently working to develop vaccines since the start of the pandemic. Though a few have been authorized for use, the Pfizer vaccine was the first to be given full approval in the United States in August 2021 – being the quickest vaccine to ever be developed. Although several vaccines produced via different approaches are in use, no mortality has been reported thus far from vaccine use. Here, we highlight the latest advances in the development of the COVID-19 vaccines, specifically the lead candidates that are in late-stage clinical trials or authorized for emergency use. As SARS-CoV-2 uses its spike protein to enter a host cell and cause infection, most vaccine candidates target this protein. This review describes the various COVID-19 vaccines - authorized and/or under development - and their composition, advantages, and potential limitations as the world continues to fight this devastating pandemic.

Sharia (Islamic Law) Perspectives of COVID-19 Vaccines

The Coronavirus disease 2019 (COVID-19) pandemic has caused health, economic, and social challenges globally. Under these circumstances, effective vaccines play a critical role in saving lives, improving population health, and facilitating economic recovery. In Muslim-majority countries, Islamic jurisprudence, which places great importance on sanctity and safety of human life and protection of livelihoods, may influence vaccine uptake. Efforts to protect humans, such as vaccines, are highly encouraged in Islam. However, concerns about vaccine products' Halal (permissible to consume by Islamic law) status and potential harm can inhibit acceptance. Fatwa councils agree that vaccines are necessary in the context of our current pandemic; receiving a COVID-19 vaccination is actually a form of compliance with Sharia law. Broader use of animal component free reagents during manufacturing may further increase acceptance among Muslims. We herein explain the interplay between Sharia (Islamic law) and scientific considerations in addressing the challenge of COVID-19 vaccine acceptance, particularly in Muslim populations.

Reinfections in COVID-19 Patients: Impact of Virus Genetic Variability and Host Immunity

The COVID-19 pandemic is still posing a devastating threat to social life and economics. Despite the modest decrease in the number of cases during September-November 2020, the number of active cases is on the rise again. This increase was associated with the emergence and spread of the new SARS-CoV-2 variants of concern (VOCs), such as the U.K. (B1.1.7), South Africa (B1.351), Brazil (P1), and Indian (B1.617.2) strains. The rapid spread of these new variants has raised concerns about the multiple waves of infections and the effectiveness of available vaccines. In this review, we discuss SARS-CoV-2 reinfection rates in previously infected and vaccinated individuals in relation to humoral responses. Overall, a limited number of reinfection cases have been reported worldwide, suggesting long protective immunity. Most reinfected patients were asymptomatic during the second episode of infection. Reinfection was attributed to several viral and/or host factors, including (i) underlying immunological comorbidities; (ii) low antibody titers due to the primary infection or vaccination; (iii) rapid decline in antibody response after infection or vaccination; and (iv) reinfection with a different SARS-CoV-2 variant/lineage. Infections after vaccination were also reported on several occasions, but mostly associated with mild or no symptoms. Overall, findings suggest that infection- and vaccine-induced immunity would protect from severe illness, with the vaccine being effective against most VOCs.

Roles of existing drug and drug targets for COVID-19 management

In December 2019, a highly transmissible, pneumonia epidemic caused by a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), erupted in China and other countries, resulting in devastation and health crisis worldwide currently. The search and using existing drugs support to curb the current highly contagious viral infection is spirally increasing since the pandemic began. This is based on these drugs had against other related RNA-viruses such as MERS-Cov, and SARS-Cov. Moreover, researchers are scrambling to identify novel drug targets and discover novel therapeutic options to vanquish the current pandemic. Since there is no definitive treatment to control Covid-19 vaccines are remain to be a lifeline. Currently, many vaccine candidates are being developed with most of them are reported to have positive results. Therapeutic targets such as helicases, transmembrane serine protease 2, cathepsin L, cyclin G-associated kinase, adaptor-associated kinase 1, two-pore channel, viral virulence factors, 3-chymotrypsin-like protease, suppression of excessive inflammatory response, inhibition of viral membrane, nucleocapsid, envelope, and accessory proteins, and inhibition of endocytosis were identified as a potential target against COVID-19 infection. This review also summarizes plant-based medicines for the treatment of COVID-19 such as saposhnikoviae divaricata, lonicerae japonicae flos, scutellaria baicalensis, lonicera japonicae, and some others. Thus, this review aimed to focus on the most promising therapeutic targets being repurposed against COVID-19 and viral elements that are used in COVID-19 vaccine candidates.

Repurposing Ivermectin for COVID-19: Molecular Aspects and Therapeutic Possibilities

As of January 2021, SARS-CoV-2 has killed over 2 million individuals across the world. As such, there is an urgent need for vaccines and therapeutics to reduce the burden of COVID-19. Several vaccines, including mRNA, vector-based vaccines, and inactivated vaccines, have been approved for emergency use in various countries. However, the slow roll-out of vaccines and insufficient global supply remains a challenge to turn the tide of the pandemic. Moreover, vaccines are important tools for preventing the disease but therapeutic tools to treat patients are also needed. As such, since the beginning of the pandemic, repurposed FDA-approved drugs have been sought as potential therapeutic options for COVID-19 due to their known safety profiles and potential anti-viral effects. One of these drugs is ivermectin (IVM), an antiparasitic drug created in the 1970s. IVM later exerted antiviral activity against various viruses including SARS-CoV-2. In this review, we delineate the story of how this antiparasitic drug was eventually identified as a potential treatment option for COVID-19. We review SARS-CoV-2 lifecycle, the role of the nucleocapsid protein, the turning points in past research that provided initial 'hints' for IVM's antiviral activity and its molecular mechanism of action- and finally, we culminate with the current clinical findings.

COVID-19: Insights into Potential Vaccines

People around the world ushered in the new year 2021 with a fear of COVID-19, as family members have lost their loved ones to the disease. Millions of people have been infected, and the livelihood of many has been jeopardized due to the pandemic. Pharmaceutical companies are racing against time to develop an effective vaccine to protect against COVID-19. Researchers have developed various types of candidate vaccines with the release of the genetic sequence of the SARS-CoV-2 virus in January. These include inactivated viral vaccines, protein subunit vaccines, mRNA vaccines, and recombinant viral vector vaccines. To date, several vaccines have been authorized for emergency use and they have been administered in countries across the globe. Meanwhile, there are also vaccine candidates in Phase III clinical trials awaiting results and approval from authorities. These candidates have shown positive results in the previous stages of the trials, whereby they could induce an immune response with minimal side effects in the participants. This review aims to discuss the different vaccine platforms and the clinical trials of the candidate vaccines.

SARS-CoV-2 vaccines: A critical perspective through efficacy data and barriers to herd immunity

Non-pharmacological interventions and tracing-testing strategy proved insufficient to reduce SARS-CoV-2 spreading worldwide. Several vaccines with different mechanisms of action are currently under development. This review describes the potential target antigens evaluated for SARS-CoV-2 vaccine in the context of both conventional and next-generation platforms.

We reported experimental data from phase-3 trials with a focus on different definitions of efficacy as well as factors affecting real-life effectiveness of SARS-CoV-2 vaccination, including logistical issues associated to vaccine availability, delivery, and immunization strategies. On this background, new variants of SARS-CoV-2 are discussed.

We also provided a critical view on vaccination in special populations at higher risk of infection or severe disease as elderly people, pregnant women and immunocompromised patients. A final paragraph addresses safety on the light of the unprecedented reduction of length of the vaccine development process and faster authorization.

What We Do Know and Do Not Yet Know about COVID-19 Vaccines as of the Beginning of the Year 2021

Coronavirus disease 2019 (COVID-19), which started at the end of 2019 and has spread worldwide, has remained unabated in 2021. Since non-pharmaceutical interventions including social distancing are facing limitations in controlling COVID-19, additional absolute means to change the trend are necessary. To this end, coronavirus-specific antiviral drugs and vaccines are urgently needed, but for now, the priority is to promote herd immunity through extensive nationwide vaccination campaign. In addition to the vaccines based on the conventional technology such inactivated or killed virus or protein subunit vaccines, several vaccines on the new technological platforms, for example, nucleic acids-based vaccines delivered by viral carriers, nanoparticles, or plasmids as a medium were introduced in this pandemic. In addition to achieving sufficient herd immunity with vaccination, the development of antiviral treatments that work specifically against COVID-19 will also be necessary to terminate the epidemic completely.

COVID-19 vaccines: Where do we stand?

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was first reported in the city Wuhan, China in December 2019. The high rates of infection led to quick spread of the virus around the world and on March 11th, 2020, the World Health Organization (WHO) announced the pandemic of the Coronavirus disease 2019 (COVID-19) caused by the SARS-CoV-2. The pharmaceutical companies and institutions have been working towards developing a safe and effective vaccine in order to control the pandemic. The biology of SARS-CoV-2 is briefly discussed describing the transcription of the virus and the receptor recognition. The spike protein of SARS-CoV-2 is important in the attachment of the host cell and RNA-dependent RNA polymerase (RdRp) is involved in the replication of the virus making them good candidates for drug and vaccine targets. To date many different strategies have been employed in the development of vaccines and a number of them are in the phase III of clinical trials with promising results. In this mini-review, we assessed the literature throughly and described the latest developments in SARS-CoV-2 vaccines for humans. The main benefits and drawbacks of each platform is evaluated and the possible changes in the vaccine effectivity due to naturally occuring SARS-CoV-2 mutations have been described.