Potential Prophylactic Treatments for COVID-19

Unlocking insights: Navigating COVID-19 challenges and Emulating future pandemic Resilience strategies with strengthening natural immunity

The original COVID-19 vaccines, developed against SARS-CoV-2, initially mitigated hospitalizations. Bivalent vaccine boosters were used widely during 2022-23, but the outbreaks persisted. Despite this, hospitalizations, mortality, and outbreaks involving dominant mutants like Alpha and Delta increased during winters when the population's vitamin D levels were at their lowest. Notably, 75 % of human immune cell/system functions, including post-vaccination adaptive immunity, rely on adequate circulatory vitamin D levels. Consequently, hypovitaminosis compromises innate and adaptive immune responses, heightening susceptibility to infections and complications. COVID-19 vaccines primarily target SARS-CoV-2 Spike proteins, thus offering only a limited protection through antibodies. mRNA vaccines, such as those for COVID-19, fail to generate secretory/mucosal immunity-like IgG responses, rendering them ineffective in halting viral spread. Additionally, mutations in the SARS-CoV-2 binding domain reduce immune recognition by vaccine-derived antibodies, leading to immune evasion by mutant viruses like Omicron variants. Meanwhile, the repeated administration of bivalent boosters intended to enhance efficacy resulted in the immunoparesis of recipients. As a result, relying solely on vaccines for outbreak prevention, it became less effective. Dominant variants exhibit increased affinity to angiotensin-converting enzyme receptor-2, enhancing infectivity but reducing virulence. Meanwhile, spike protein-related viral mutations do not impact the potency of widely available, repurposed early therapies, like vitamin D and ivermectin. With the re-emergence of COVID-19 and impending coronaviral pandemics, regulators and health organizations should proactively consider approval and strategic use of cost-effective adjunct therapies mentioned above to counter the loss of vaccine efficacy against emerging variants and novel coronaviruses and eliminate vaccine- and anti-viral agents-related serious adverse effects. Timely implementation of these strategies could reduce morbidity, mortality, and healthcare costs and provide a rational approach to address future epidemics and pandemics. This perspective critically reviews relevant literature, providing insights, justifications, and viewpoints into how the scientific community and health authorities can leverage this knowledge cost-effectively.

Exploring the Role of Antiviral Nasal Sprays in the Control of Emerging Respiratory Infections in the Community

INTRODUCTION

The COVID-19 pandemic has demonstrated that there is an unmet need for the development of novel prophylactic antiviral treatments to control the outbreak of emerging respiratory virus infections. Passive antibody-based immunisation approaches such as intranasal antibody prophylaxis have the potential to provide immediately accessible universal protection as they act directly at the most common route of viral entry, the upper respiratory tract. The need for such products is very apparent for SARS-CoV-2 at present, given the relatively low effectiveness of vaccines to prevent infection and block virus onward transmission. We explore the benefits and challenges of the use of antibody-based nasal sprays prior and post exposure to the virus.

METHODS

The classic susceptible-exposed-infectious-removed (SEIR) mathematical model was extended to describe the potential population-level impact of intranasal antibody prophylaxis on controlling the spread of an emerging respiratory infection in the community.

RESULTS

Intranasal administration of monoclonal antibodies provides only a short-term protection to the mucosal surface. Consequently, sustained intranasal antibody prophylaxis of a substantial proportion of the population would be needed to contain infections. Post-exposure prophylaxis against the development of severe disease would be essential for the overall reduction in hospital admissions.

CONCLUSION

Antibody-based nasal sprays could provide protection against infection to individuals that are likely to be exposed to the virus. Large-scale administration for a long period of time would be challenging. Intranasal antibody prophylaxis alone cannot prevent community-wide transmission of the virus. It could be used along with other protective measures, such as non-pharmaceutical interventions, to bridge the time required to develop and produce effective vaccines, and complement active immunisation strategies.

DYNAMICS OF CLINICAL SYMPTOMS AND SECRETORY IMMUNOGLOBULIN A IN COVID-19 CONVALESCENT PATIENTS

The post-COVID-19 recovery period is characterized by persistence of some symptoms, with immunological alterations being of great importance. Development of preventive measures to normalize mucosal immunity after a coronavirus infection determines the relevance of the current study. The aim. To study dynamics of clinical symptoms and level of secretory immunoglobulin A in individuals after a novel coronavirus infection as well as evaluate effectiveness of using interferon alpha-2b. Materials and methods. A study was conducted with patients aged 18 to 60 years old (n=130), surveyed 1 to 9 months after post-infection, as well as in apparently healthy individuals lacking COVID-19 (n=15). Previous novel coronavirus infection and post-COVID manifestations were verified based on medical documentation, complaints, anamnesis data, physical examination and questionnaires. The concentration of salivatory and nasopharyngeal mucosal sIgA was measured dynamically prior to and after administration of local therapy with interferon alpha-2b (gel applied intranasally twice a day for 30 days). Results. The acute period of COVID-19 was characterized by fever, anosmia, fatigue and weakness, muscle and joint pain. Among the post-COVID manifestations at early period (1-3 months), pain in the joints and muscles (75,0%) as well as elevated body temperature (21,2%) were reliably detected, whereas in the long period (6-9 months) there were revealed dominance with the same frequency of shortness of breath, muscle and joint pain (75,8%, respectively). Based on examination data in healthy subjects, there was determined an arbitrary normal range of secretory IgA in saliva 6.451.81 mg/ml and nasal swabs 13.433.24 mg/ml. In the group of patients 1-3 months post-infection, therapy with interferon alfa-2b one month later resulted in significantly increased level of secretory IgA in saliva (from 1.840.28 to 5.781.96 mg/ml) and in nasal swabs (from 28.613.0 to 39.833.85 mg/ml) by more than 3- and 1.5-fold, respectively. In the group of patients without therapy was featured with stably sustained decline in sIgA level up to 9 months after COVID-19. In particular, the level of saliva sIgA ranged from 2.360.56 down to 2.160.66 mg/ml, and in nasal smears from 15.661.32 to 10.231.07 mg/ml that differed insignificantly compared to baseline level. The rate of respiratory diseases prevailed in this group (27.6% of cases), which fully lacked in the group of topically administered interferon alpha-2b. Conclusion. In the post-COVID period, multiple organ disorders persist and reduced sIgA level is registered. Intranasally applied interferon alfa-2b made possible to normalize sIgA level and prevent accumulation of respiratory infectious pathologies.

COVID-19 prophylaxis with doxycycline and zinc in health care workers: a prospective, randomized, double-blind clinical trial

OBJECTIVES

This study aims to assess the efficacy of a combination treatment of doxycycline and zinc in the primary prevention of COVID-19 infection in Tunisian health care workers compared with two control groups.

METHODS

We conducted a prospective, randomized, double-blind clinical trial over 5 months to determine the efficacy of a preventive combination treatment dose of doxycycline (100 mg/day) and zinc (15 mg/day), compared with a single-dose treatment with doxycycline versus placebo. The effectiveness of preventive treatment was measured by the significant decline in the number of cases of COVID-19 infection and/or a decrease in the viral load as determined by SARS-CoV-2 cycle threshold value using reverse transcription polymerase chain reaction tests.

RESULTS

We detected a significant decrease of SARS-CoV-2 infection in the group that received both doxycycline and zinc compared with other participants. We also demonstrated that COVID-19 infection was neither associated with diabetes (P = 0.51) nor associated with hypertension (P = 0.99), asthma (P = 0.52), and chronic obstructive pulmonary disease (P = 0.27).

CONCLUSION

Our findings indicated that preventive therapy reduced the risk of SARS-CoV-2. These results suggest that the combination of doxycycline and zinc has a protective effect in patients with SARS-CoV-2 infection.

Synthetic Heparan Sulfate Mimetic Pixatimod (PG545) Potently Inhibits SARS-CoV-2 by Disrupting the Spike-ACE2 Interaction

Heparan sulfate (HS) is a cell surface polysaccharide recently identified as a coreceptor with the ACE2 protein for the S1 spike protein on SARS-CoV-2 virus, providing a tractable new therapeutic target. Clinically used heparins demonstrate an inhibitory activity but have an anticoagulant activity and are supply-limited, necessitating alternative solutions. Here, we show that synthetic HS mimetic pixatimod (PG545), a cancer drug candidate, binds and destabilizes the SARS-CoV-2 spike protein receptor binding domain and directly inhibits its binding to ACE2, consistent with molecular modeling identification of multiple molecular contacts and overlapping pixatimod and ACE2 binding sites. Assays with multiple clinical isolates of SARS-CoV-2 virus show that pixatimod potently inhibits the infection of monkey Vero E6 cells and physiologically relevant human bronchial epithelial cells at safe therapeutic concentrations. Pixatimod also retained broad potency against variants of concern (VOC) including B.1.1.7 (Alpha), B.1.351 (Beta), B.1.617.2 (Delta), and B.1.1.529 (Omicron). Furthermore, in a K18-hACE2 mouse model, pixatimod significantly reduced SARS-CoV-2 viral titers in the upper respiratory tract and virus-induced weight loss. This demonstration of potent anti-SARS-CoV-2 activity tolerant to emerging mutations establishes proof-of-concept for targeting the HS-Spike protein-ACE2 axis with synthetic HS mimetics and provides a strong rationale for clinical investigation of pixatimod as a potential multimodal therapeutic for COVID-19.

[The problem of the use of interferons in the novel coronavirus disease COVID-19 (Coronaviridae: Coronavirinae: Betacoronavirus: Sarbecovirus)]

By the end of 2021, about 200 studies on the effect of interferons (IFNs) on the incidence and course of the new coronavirus infection COVID-19 (Coronaviridae: Coronavirinae: Betacoronavirus: Sarbecovirus) have been reported worldwide, with the number of such studies steadily increasing. This review discusses the main issues of the use of IFN drugs in this disease. The literature search was carried out in the PubMed, Scopus, Cochrane Library, Web of Science, RSCI databases, as well as in the Google Scholar preprint database using the available search queries «MeSH for coronavirus», «SARS-CoV-2», «IFN drugs», and «COVID-19». Interferon therapy is indicated for early administration (within the first 5 days of patient admission) in cases of mild to moderate COVID-19 to take advantage of the narrow therapeutic window of IFNs action. Control and suppression of viral replication requires therapy with IFNs and other effective antiviral agents that inhibit the reproduction of SARS-CoV-2 and induce several interferon-stimulated genes (ISG). Type I IFNs (IFN-I) exhibit potent pro-inflammatory properties and activate a wide variety of different cell types that respond to IFNs stimulation and pathogen entry. IFN-III confer local mucosal antiviral immunity without inducing the strong systemic pro-inflammatory responses associated with IFN-I. The use of IFNs drugs in the therapy of new coronavirus infection requires a cautious and differentiated approach, because in severe cases they can aggravate viral pathogenesis by causing excessive intensity of inflammatory reactions. The unique biological properties of substances of this class allow us to consider them as therapeutic agents with significant potential for use in patients with COVID-19.

Zinc and selenium supplementation in COVID-19 prevention and treatment: a systematic review of the experimental studies

BACKGROUND AND AIM

The COVID-19 pandemic has severely affected the world's population in the last two years. Along with non-pharmacological public health interventions, major efforts have also been made to identify effective drugs or active substances for COVID-19 prevention and treatment. These include, among many others, the trace elements zinc and selenium, based on laboratory studies and some observational human studies. However, both of these study designs are not adequate to identify and approve treatments in human medicine, and experimental studies in the form of randomized controlled trials are needed to demonstrate the effectiveness and the safety of any interventions.

METHODS

We undertook a systematic review in which we searched for published and unpublished clinical trials using zinc or selenium supplementation to treat or prevent COVID-19 in the Pubmed, Scopus and ClinicalTrials databases up to 10 January 2022.

RESULTS

Amongst the published studies, we did not find any trial with selenium, whereas we retrieved four eligible randomized clinical trials using zinc supplementation, only one of which was double-blind. One of these trials looked at the effect of the intervention on the rate of new SARS-CoV-2 infections, and three at the COVID-19 clinical outcome in already infected individuals. The study populations of the four trials were very heterogeneous, ranging from uninfected individuals to those hospitalized for COVID-19. Only two studies investigated zinc alone in the intervention arm with no differences in the endpoints. The other two studies examined zinc in association with one or more drugs and supplements in the intervention arm, therefore making it impossible to disentangle any specific effects of the element. In addition, we identified 22 unpublished ongoing clinical trials, 19 on zinc, one on selenium and two on both elements.

CONCLUSION

No trials investigated the effect of selenium supplementation on COVID-19, while the very few studies on the effects of zinc supplementation did not confirm efficacy. Therefore, preventive or therapeutic interventions against COVID-19 based on zinc or selenium supplementation are currently unjustified, although when the results of the on-going studies are published, this may change our conclusion.

Preclinical Evaluation of Chicken Egg Yolk Antibody (IgY) Anti-RBD Spike SARS-CoV-2—A Candidate for Passive Immunization against COVID-19

The coronavirus disease 2019 (COVID-19) has become a substantial threat to the international health sector and the global economy. As of 26 December 2021, the number of mortalities resulting from COVID-19 exceeded 5.3 million worldwide. The absence of an effective non-vaccine treatment has prompted the quest for prophylactic agents that can be used to combat COVID-19. This study presents the feasibility of chicken egg yolk antibody (IgY) anti-receptor-binding domain (RBD) spike SARS-CoV-2 as a strong candidate to neutralize the virus for application in passive immunization. For the purpose of preclinical studies, we radiolabeled IgY anti-RBD spike SARS-CoV-2 with radionuclide iodine-131. This allowed us to evaluate several biological characteristics of IgY in vitro, in vivo, and ex vivo. The preclinical data suggest that IgY anti-RBD spike SARS-CoV-2 could specifically bind to the SARS-CoV-2 antigens; however, little uptake was observed in normal cells (MRC-5) (<2%). Furthermore, the ex vivo biodistribution study revealed that IgY predominantly accumulated in the trachea of normal mice compared to other organs. We also found that IgY possessed a good safety profile when used as an intranasal agent. Taken together, we propose that IgY anti-RBD spike SARS-CoV-2 has the potential for application in passive immunization against COVID-19.

DNA aptamers masking angiotensin converting enzyme 2 as an innovative way to treat SARS-CoV-2 pandemic

All the different coronavirus SARS-CoV-2 variants isolated so far share the same mechanism of infection mediated by the interaction of their spike (S) glycoprotein with specific residues on their cellular receptor: the angiotensin converting enzyme 2 (ACE2). Therefore, the steric hindrance on this cellular receptor created by a bulk macromolecule may represent an effective strategy for the prevention of the viral spreading and the onset of severe forms of Corona Virus disease 19 (COVID-19). Here, we applied a systematic evolution of ligands by exponential enrichment (SELEX) procedure to identify two single strand DNA molecules (aptamers) binding specifically to the region surrounding the K353, the key residue in human ACE2 interacting with the N501 amino acid of the SARS-CoV-2 S. 3D docking in silico experiments and biochemical assays demonstrated that these aptamers bind to this region, efficiently prevent the SARS-CoV-2 S/human ACE2 interaction and the viral infection in the nanomolar range, regardless of the viral variant, thus suggesting the possible clinical development of these aptamers as SARS-CoV-2 infection inhibitors. Our approach brings a significant innovation to the therapeutic paradigm of the SARS-CoV-2 pandemic by protecting the target cell instead of focusing on the virus; this is particularly attractive in light of the increasing number of viral mutants that may potentially escape the currently developed immune-mediated neutralization strategies.

COVID-19 in 2021

The Special Issue on Vaccines and Therapeutics against Coronaviruses, which was launched in early 2021, has attracted the scientific community at large, and more than 20 manuscripts have been accepted for publication.[...].