key: cord-0252210-jn3leulz
authors: Adedokun, Kamoru A.; Olarinmoye, Ayodeji O.; Olayemi, Lawal O.; Shehu, Muhammed R.; Mustapha, Jelili O.; Kamorudeen, Ramat T.; Nassar, Sulaimon A.
title: Addressing the global surge of COVID-19 cases: Insights from diagnostics, improved treatment strategies, vaccine development and application
date: 2021-03-12
journal: J Clin Transl Res
DOI: nan
sha: 5f54f3bea72df434c10e582fe2947fcf0e76d4dd
doc_id: 252210
cord_uid: jn3leulz

BACKGROUND AND AIM: As the rage of coronavirus disease 2019 (COVID-19) pandemic continues to spread globally, much effort is being directed to contain it through various efforts – genomic studies, drug discoveries, clinical trials, vaccine development, and the innovation of diagnostic techniques. However, some pertinent areas involving accurate and sensitive diagnostics, immunoglobulin specificity, evolution of mutant strains of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the drug combination strategy to combat it still require more attention. METHODS: This review critically examines the COVID-19 response and containment operations. It also addresses some standing challenges involving the areas of diagnostics, vaccine development and prospect, and treatment strategies in relation to antiviral drug treatment and immunotherapy. Designated set of keywords such as “SARS-CoV-2;” “coronavirus;” “severe acute respiratory syndrome coronavirus;” “repurposed;” “vaccination;” “containment;” “laboratory diagnostic;” “immunotherapy;” “antiviral;” “antiparasitic;” “antibiotic;” “antiprotozoal;” “antibody;” “anti-inflammatory;” “antitumor;” “corticosteroid;” “hypertensive drug;” “statin;” “supplement;” and “biological” along with “COVID-19” were inserted on electronic databases to retrieve articles and clinical trial information relevant to the study objectives. The search databases included ClinicalTrials.gov, NIH.gov, PubMed, Scinapse, CINAHL, Medline, Google Scholar, Academic Search Premier, SAGE, EBSCO Host, and Scopus. RELEVANCE FOR PATIENTS: The difficulties associated with SARS-CoV-2 rapid mutations are unceasingly evolving and re-evolving. These pose serious concerns and downplay the efficacy and effectiveness of the current pipeline antiviral drugs and vaccines. Entities encompassing immunotherapy, antiviral drug therapies, viral genomics, protein-protein interaction, and improved diagnostics as well as drug combination strategy against the emerging genetic variability of SARS-CoV-2 were critically appraised. This study suggests that robust collaborations in the development of more sensitive, rapid and accurate diagnostics, development of immunoglobulin specific agents and improved anti-viral treatment focus against multiple mutant genes of SARS-CoV-2 should be aggressively pursued for the overall benefits of COVID-19 patients.

The year 2019 ended with a global alarm in the form of an outbreak of a new strain of coronavirus called the Severe Acute Respiratory Syndrome Coronavirus Type 2 (SARS-CoV-2). On December 31, 2019, the World Health Organization (WHO) alerted the global health community of the occurrence of a cluster of pneumonia cases in Wuhan city in the Hubei Province of China [1] . The toll of COVID-19 in terms of morbidity and mortality has been massive, especially in countries such as the United States, Italy, Spain, Germany, France, Republic of Korea and Iran [2] . As COVID-19 continues to spread worldwide, much effort is being directed by governments, the WHO, and other organizations to contain it through travel restrictions and social distancing. Researchers have swung into various actions including genomic studies, clinical trials, vaccine development, drug discoveries, and the innovation and improvement of diagnostic techniques. However, these efforts have resulted in limited success as the disease continues to spread unabatedly.

Recently, a big concern erupted over the dynamic antigenic drift of SARS-CoV-2 due to the discovery of about 14 mutant strains. From the available report, the existing immunogens and diagnostic reagents are normal products of the sequence of spike proteins from the index strain from Wuhan [3] . By indication, alteration in these spike proteins, the most studied domain in SARS-CoV-2 could result in reduced sensitivity to neutralizing antibodies and false testing outcomes against any new strains. Sooner or later, the emergence of new strains may outpace the ongoing interventions including vaccine design, diagnostic development, and the efficacy of the drug treatments.

Many therapeutic agents have also been tested against SARS-CoV-2, so far, very few remain hopeful. Even though there is currently no specific drug available to treat COVID-19, a number of clinical trials are premised on repurposed drugs, biologicals, and occasionally dietary supplementations. These therapeutic agents are believed to serve various curative and preventive purposes either alone or in combination. Major classes among these medications are: Antivirals (such as remdesivir, lopinavir/ ritonavir, favipiravir, darunavir, ribavirin, elbasvir, tegobuvir, nelfinavir, and arbidol); broad spectrum anti-parasitics (such as nitazoxanide); broad spectrum synthetic serine protease inhibitor (such as nafamostat); antimalarials (such as artemisinin/ artesunate, chloroquine, and hydroxychloroquine); antibiotics (such as azithromycin); antibodies/biologicals (such as interferon β1b and tocilizumab); and antitumor drugs (such as ruxolitinib), among others [4] [5] [6] , Table 1 . Sadly, the ongoing emergency choices in repurposed drugs are not without associated problems, mainly, adverse drug reactions that have resulted in cardiac problems, liver and gastrointestinal system disorders in those that are treated [31] [32] [33] [34] . Lopinavirritonavir and interferon-β combination have been associated with self-limited nausea and diarrhea [35] . Chloroquine/ Hydroxychloroquine therapy at therapeutic doses has been associated with side effects including electrocardiographic changes, retinopathy, myopathy, headaches, dizziness, and gastrointestinal upset [6] . Myopathy and rhabdomyolysis are the most frequent adverse effects of Statins [36] . Darunavir is associated with increased risk of myocardial infarction, especially in HIV co-infected patients [37] , while Ribavirin plus Lopinavir/Ritonavir combination caused a significant increase in adverse gastrointestinal effects [38] . The common adverse effects of Remdesivir in severely infected COVID-19 patients have included nausea, acute respiratory failure, increased alanine aminotransferase (ALT) and constipation [39] , and liver toxicity linked to tocilizumab [6] . However, there is currently a dearth of information to determine whether some of these adverse events are a result of the unstable SARS-CoV-2 genetic components, or due to individual patient response which may demand new treatment strategies.

Furthermore, studies into the development of COVID-19 vaccines are underway with some vaccine trials showing promising outcomes. It is important to note that the emergence of SARS-CoV-2 rapid mutations may prompt various challenges against the success of the ongoing vaccines, including potential immunopathological reactions based on the knowledge of vaccine development from MERS and SARS [40, 41] . It is also worthy of note that vaccines for MERS and SARS diseases are yet to be approved. Apart from the concerns over the success of SARS-CoV-2 vaccine design, the poor diagnostics that currently pose a huge threat to COVID-19 containment operations are another source of worry [42] . A study report has it that due to poor sensitivity and low reliability, several available antibody test kits have failed to detect early (presymptomatic) infection of COVID-19 and failed to identify asymptomatic carriers, who constitute the largest proportion of COVID-19 patients [42] .

The present report, therefore, examines and addresses some current, budding and future challenges, which include diagnostics, vaccine development and prospect, and treatment strategies in relation to antiviral therapy. It also offers some useful research information to the body of available data, which may facilitate the containment and response operations against the global battle of COVID-19.

Familial and nosocomial contacts and community spread fuel and sustain the current rapid human-human transmission of SARS-CoV-2 virus in many countries [43] . Despite the rapid spread of the virus, there has been very little interest in identifying how the index case originally occurred, compared with the effort and resources being expended in search of cure and prevention. Nonetheless, the source of contact is widely believed to be a wet market in Wuhan where wild animals are traded [44] . in addition, it has been established that the first SARS virus (SARS-CoV) was initially transmitted from bats to civet cats and in MERS-CoV, from bats to camels before transmission to humans became possible in their transmission pathways. However, the potential reservoir and intermediate hosts of SARS-CoV-2 have not been conclusively identified (Figure 1) .

The SARS-CoV-2 virus is a Beta-coronavirus, same as MERS-CoV and SARS-CoV; all the three viruses have their origins in bats. However, in the case of SARS-CoV-2, it is pangolins that have somewhat cautiously been implicated as the intermediate hosts [45, 46] . Recent evidence-based phylogenetic comparison Inhibits viral RNA-dependent polymerase and induces a negative proofreading activity ( Figure 2 ).

Respiratory failure and organ impairment, anaphylactoid reactions, heart rhythm disorders angioedema, diarrhea, skin rash, and hypotension, among others.

NCT04575064 Germany [7, 8] Lopinavir/Ritonavir Phase III/March, 2021

Lopinavir is a peptidomimetic protease inhibitor combined with ritonavir. (Figure 2 ). Targets the main protease (Mpro) of SARS-CoV-2, a key protease enzyme required for the virus to replicate and assemble itself.

Allergic reaction, erectile dysfunction, libido, arrhythmia, abdominal pain, hyperlipidemia, nausea, among many others.

NCT04364022 Switzerland [8, 9] Favipiravir Phase III/ September, 2020

Inhibits of SARS-CoV-2 with other closely related reference genomes revealed up to 96% similarity with bat SARS-like coronavirus strain, BatCov RaTG13 [47] . In addition, the detection of SARS-CoV-2 in human airway epithelial cell lines (Vero E6 and Huh-7) and transgenic animals show characteristic induction of multifocal pneumonia and interstitial hyperplasia [47] . These findings suggest that SARS-CoV-2 invades the pulmonary and intestinal tracts. Although, there is no definite agent identified with the index case till date, available phylogenetic evidence in combination with the cellular tropism shows that SARS-CoV-2 has a zoonotic origin and that it is associated with respiratory and gastro-intestinal infections.

Because there is lack of a definite answer regarding whether the index case of COVID-19 was really due to zoonotic transmission, the current pandemic situation continues to generate misconceptions and misinformation in the public space [48] . One of the conspiracy theories describes SARS-CoV-2 as a biological weapon that was stealthily deployed during a covert spy operation between disputing nations. Other "infodemics" about COVID-19 include false claims of treatment breakthroughs, herbal remedies, biological mutation of the virus, and the right brand and proper usage of nose masks, among others [48] .

According to the Chinese Center for Disease Control and Prevention (China CDC), clinical manifestations of COVID-19 are used in categorizing the patients into three disease groupsmild, severe, and critical. The mild COVID-19 manifestation category involves 81% of the patients. They often show no signs of pneumonia, or occasionally develop a mild symptom. However, the severe and critical cases present with a wide range of symptoms and pulmonary dysfunctions. Severe cases of COVID-19 occur only in 14% of patients, with the critical ones occurring only in 5% [49] . Asymptomatic SARS-CoV-2 carriers may be contagious [50] , and a major barrier militating against rapid response and containment operations against COVID-19 is the failure to detect such virus shedders early enough to prevent the spread of the infection. Hence, urgent attention has been shifted to the development of newer, more rapid and accurate diagnostic tools to facilitate early contact tracing and rapid detection of COVID-19 cases, especially the asymptomatic individuals who may also shed the virus [42, 51] .

Several laboratory diagnostic methods -RT-PCR, serological tests such as ELISA among others have been developed and are currently in use. However, studies show that there is still a serious concern about the reliability of the major diagnostic tools for COVID-19 detection [52, 53] . The reverse-transcriptasepolymerase-chain-reaction (RT-PCR) is considered a robust, specific, and reliable technique and has been well documented in the diagnoses of various viral infections such as ebolavirus disease, Zika, and influenza. Unfortunately, false-negative rates are now commonly reported for RT-PCR in COVID-19. Of note, Wikramaratna et al. [53] reported a high rate of 41% falsenegative COVID-19 RT-PCR, indicating poor sensitivity akin to other laboratory tests with variable accuracy [54] .

In a study that involved a systemic review of 957 patients, it was observed that false-negatives in RT-PCR assays could be as high as 29% [55] . A similar study involving more than a thousand test samples also assessed the accuracy level in RT-PCR assay and reported 38% median false-negative rate for the tests conducted on the 1 st day of symptom onset and 20% 3 days later [56] . Meanwhile, several diagnostic tests are available for COVID-19 patients, but until now there is no reference-standard test otherwise known as "gold standard" for SARS-CoV-2 tests.

In addition to molecular diagnostics, various rapid point-of-care kits for testing SARS-CoV-2 antibodies have been manufactured and marketed far and wide. These tests are basically qualitative and thus can only detect whether SARS-CoV-2 antibodies are present or not [57] . Besides, SARS-CoV-2 antibodies may be impacted by unavoidable cross-reactivity with other coronaviruses, especially the original SARS-CoV [52] . For these reasons, a great caution would be required in interpreting their results, especially to inform patients' decisions.

Serology is fast evolving as a vital diagnostic tool for COVID-19 especially in spotting individuals with immunity against the SARS-CoV-2 infection, over time. Serological tests may be useful only for patients who present late, especially after the first 2 weeks following the onset of COVID-19 symptoms [52] . Even more concerning is the report that that the level of the earliest most sensitive antibody titer begins to rise only after the 2 nd week following the manifestation of symptoms [58] . In other words, serological test may not merit detection of early infection with SARS-CoV-2 especially in the presymptomatic, who are potential SARS-CoV-2 "silent spreaders."

The common approaches of detecting asymptomatic patients are through massive screening and good follow-up. However, to wait for possible development of symptoms in both presymptomatic and "asymptomatic" individuals may not represent the best approach since these groups of patients could still fuel the contagion. Therefore, a rapid point-of-care test with improved sensitivity and specificity is the required tool. To achieve this, the Food and drug Administration (FDA) must lay down a "gold standard" test for all COVID-19 diagnostic tests as a reference point. Apart from the diagnostic methods, other challenges such as sampling and transportation problems are fast evolving and contribute to the unreliability of test outcomes. Among the sampling related factors are varying anatomic sites, improper labeling, and wrong virus cycle timing.

While inaccurate diagnostic results constitute a challenge to the containment of the pandemic, it is suggested that researchers should focus inwards on a range of methodological expertise, where accurate and early detection of SARS-CoV-2 could be made possible soon after contracting the disease. A previous report showed the potential use of respiratory virus testing panel (RVTP) for rapid diagnosis of COVID-19 [42] , especially with possible rise in SARS-CoV-2 mutant strains. The development of RVTPs that are highly sensitive and specific to multi-strain SARS-CoV-2 targets, if commercially available, will no doubt aid in combating the transmission of SARS-CoV-2 more rapidly. It would also facilitate early confirmation of the suspected cases and identify the asymptomatic SARS-CoV-2 virus silent shedders. Since RVTPs may provide coverage for broader virus strains, its analytical sensitivity and specificity can be rapidly measured and identified. This would aid in shortening the turnaround diagnostic time and minimizing false results. It is also believed that RVTPs could circumvent the impacts of sampling and transportation errors, which may contribute to the bane of accurate testing. RVTPs may detect COVID-19 cases rapidly, especially if this is manufactured with a good reference guide to ensure high testing accuracy.

The purpose of antiviral therapy is to lower viremia in patients in the acute phase of infection, to allow the body to recover, and to give the immune system time to mount up a specific response that will neutralize the pathogen and halt its continued spread. According to a recent report, there have been few completed clinical trials on the efficacy of antiviral therapy in the management of COVID-19 patients [59] . One of such clinical trials involved the addition of Lopinavir-Ritonavir to the standard treatment regimen of patients with severe COVID-19 (i.e., the use of antibiotics, invasive or non-invasive ventilation and extracorporeal membrane oxygenation (ECMO), and vasopressor). In effect, it did not improve clinical outcomes of 28-day mortalities and viral RNA load significantly [60] . It is, therefore, suggested that a combination of three antivirals: Lopinavir-Ritonavir and Remdesivir could provide a synergistic mechanism against SARS-CoV-2. However, such combination may induce adverse effects. Lopinavir and Ritonavir are protease inhibitors, previously used in the treatment of Acquired immunodeficiency syndrome (AIDS). They prevent viral replication by selectively binding to viral proteases, thus blocking the proteolytic cleavage of protein precursors required for viral replication [4] . Ritonavir inhibits the metabolism of Lopinavir and increases its plasma concentration [61] Table 1 and Figure 2 .

Another antiviral agent Remdesivir, initially used in the therapeutic management of Ebola patients, is still undergoing wide-scale; multi-center clinical trials and the preliminary results suggest its efficacy in the treatment of patients with severe COVID-19 [62] . Remdesivir or GS-5734 is a broad-spectrum antiviral medication. It diffuses into cells where its active triphosphate metabolite GS-441524 interferes with the action of viral RNA-dependent RNA polymerase and evades proofreading by viral exoribonuclease (ExoN), leading to a reduction in viral RNA production [63] . Due to the emergence of varying mutants of SARS-CoV-2 and the genetic variability of individual patients, it may be important to consider synergistic effects or combinations of various potential repurposed drug candidates and their assessments when varying individual treatment options for management of COVID-19 ( Figure 2) .

In another recently concluded clinical trial, Veklury (Remdesivir) was superior to placebo in shortening the time to recovery in adults who were hospitalized with COVID-19 and had evidence of lower respiratory tract infection [64] . To help in accelerating the development of this promising drug, the Food and Drug Administration FDA through its coronavirus treatment acceleration program gave an approval for the use of Veklury (Remdesivir) in adults and pediatric patients [64] . Under a mechanism called emergency use authorization (EUA), Veklury (Remdesivir) can be used for treatment of suspected or laboratory confirmed COVID-19 in hospitalized pediatric patients weighing 3.5 kg to less than 40 kg or hospitalized pediatric patients less than 12 years of age weighing at least 3.5 kg [64] . Another agent; Bamlanivimab has also received EUA from the FDA as a monotherapy in adult and pediatric outpatients with mild-to-moderate COVID-19, and with positive results of direct SARS-CoV-2 viral testing who are 12 years of age and older weighing at least 40 kg, and who are at high risk for progressing to severe COVID-19 and/or hospitalization [65] .

Moreover, other studies focusing on the structural genetics (structural and non-structural proteins SP/NSP) and mRNA biological mechanisms of SARS-COV-2 pathogenesis and immune evasion of the host cell will be beneficial in unlocking regions for drug targets, vaccine delivery and host immunological response. By addressing the therapeutic challenges based on the therapies that target the host-virus interface, where the emergence of mutational resistance is arguably less likely, could potentially present durable, broad-spectrum treatment modalities [66] . This could be achieved through systematic mapping of the interaction landscape between the SARS-CoV-2 proteins and human proteins, especially in emerging mutated strain of SARS-CoV-2.

Scientists have been able to unwind the SARS-CoV-2 host infectivity fuelled by enzymatic and antibody kinetics. SARS-CoV2 infection regulates host kinase signaling and virus kinase phosphorylation with its activity driven by host proteome [67] . The top kinase families predicted by sequence to regulate these sites included casein kinase II (CK2), cyclin-dependent kinase (CDK), and protein kinase C (PKC), among others, suggesting that these kinases may contribute to the regulation of viral replication. It is also observed that SARS-CoV-2 makes use of the host post-translational regulatory systems to promote rapid changes in cellular signaling [67] . Kinases represent ideal drug targets and the ongoing studies on the antiviral activity of 68 drugs and compounds approved by the FDA are aggressively pursued. Some of these agents are in clinical testing stage or under preclinical development for various diseases, including silmitasertib (CK2, phase 2), gilteritinib (AXL, FDA approved), ARRY-797 (p38, phase 2/3), MAPK13-IN-1 (p38, preclinical), SB203580 (p38, preclinical), ralimetinib (p38, phase 2), apilimod (PIKFYVE, phase 1), and dinaciclib (CDK, phase 3), among others [62] . Similarly, multiplexed enzyme-linked immunosorbent assay (ELISA) analysis of supernatants of cells from in vitro experiments demonstrated strong upregulation of inflammatory cytokines at the protein level. It is believed that these agents and diagnostic techniques could offer various potentials for viral inhibition; activation of host immunological response by T and B cells associated cellular proteins and the monitoring of disease duration.

The use of intravenous immunoglobulin (IVIg) therapy shows potential value as an effective adjunct measure in the treatment of several acute infections, including viral pneumonias such as SARS-CoV-2 [68] . According to a recent report, the commencement of IVIg <48 h of hospital admission to intensive care unit may prevent clinical demands such as the need for mechanical ventilation and the length of hospital stay. It also advances the early recovery of patients and improves considerable level of clinical efficacy [69] .

However, a separate report implies that there is a limited benefit of IVIg therapy. It concluded that the treatment efficacy of IVIg would be better only if the immune IgG antibodies are pooled from the patients who recovered from COVID-19 in the same locality such as in the same city or the surrounding area. This can raise the possibility of neutralizing the virus [70] . The inherent limitations are that the harvested antibodies will not have widespread use and that the quantity that is available for use in the treatment of acute COVID-19 patients will depend on the number of recovered patients in each locality and the willingness of the individuals to donate immune sera. However, an alternative may lie in the use of cocktails of blocking monoclonal antibodies that specifically target and neutralize epitopes of predominant strains of SARS-CoV-2 circulating in wider geographical areas. Meanwhile, human monoclonal antibodies have been reported with the potential to block the binding of SARS-CoV-2 spike protein to angiotensin-converting enzyme 2 receptor sites of host cells [71] . A monoclonal antibody targeting the spike protein S1 of SARS-CoV-2, made from immunized transgenic mice expressing human Immunoglobulin (Ig) was reported to neutralize both SARS-CoV-2 and SARS-CoV infection [3] .

At present, various Igs are showing fruitful experimental outcomes as a promising class of drugs, it is believed that these proteins can, therefore, be produced ad infinitum in cell culture vats using hybridoma technology. Hybridoma technology could circumvent the need to pool intravenously or recruit patients who recovered from the disease once the genetic variants are fully identified. This may remove the barrier of the limited amount of harvested sera, and obviate the problem of the evolving constant mutation by the virus, using specific monoclonal antibodies through this technology. In this process, an antigen (or its epitope) is injected into a mammal to stimulate its immune system's B-cells and produces neutralizing antibodies specific to the antigen. Furthermore, the antibody-producing B-cells are harvested and fused with a myeloma (immortal B cell cancer cells) in vitro to produce a hybrid cell line (a hybridoma), which retains the antibody-producing ability of the B-cell and the reproducibility of the myeloma.

A collection of various SARS-CoV-2 hybridomas from varying genetic mutants and preparation of a range of serotypes from immunized cells, followed with a proper characterization and purification processes could be a novel idea to produce cocktails of SARS-CoV-2 blocking monoclonal antibodies. Likewise, the use of Ig combination specific to different antigenic sites from different strains may limit the problems of treatment resistance occasioned by genetic variants and immune escape and thus offer a useful treatment option.

The SARS-CoV-2 has demonstrated a remarkable ability to mutate. There has been an identified unexpected relationship between the SARS-CoV-2 mutation densities and viral transmission dynamics at different levels among human populations. A total of 14 new strains of the virus apart from the one originally identified in Wuhan have been characterized, and each has reportedly fueled regional epidemics such as those witnessed in Asia, Europe, North America, and Latin America [72] . Spike mutation pipeline reveals the emergence of a more transmissible form of SARS-CoV-2. A pathogen that mutates rapidly will, each time, present a new epitope, antigenic determinant or antigen molecule to which an antibody attaches, to the immune system. Meanwhile, the immune system is expected to respond by producing newer, specific antibodies that will bind to and neutralize the new epitope. It is, therefore, imperative to state that not all antibodies produced against epitopes of different strains of a pathogen are crossprotective. It is perhaps why an increasing number of COVID-19 patients are re-testing positive after recovery, although still unclear at this time if this is a result of the reactivation of the virus in the patients as opposed to re-infection [73, 74] .

It is important at this juncture, to add that evolving mutational significance in SARS-COV-2 termed synonymous and nonsynonymous mutations is imminent. About this, mutational changes have been identified from COVID-19 cases in the highest hit countries including the United State of America (USA) and United Kingdom (UK) [75] . Studies have shown that SARS-COV-2 14408 C>T and 23403 A>G mutations are associated with an increase in mutation density over time [75] . The report further shows that there exists a strong positive correlation between non-synonymous mutational densities and time with 14408 C>T/23403 A>G genotypes of SARS-CoV-2 in both the UK and US. These changes were identified among the "wild type" and "mutant" strains of SARS-CoV-2 [75] . Understanding the biological disparities between the "mutant" and "wild type" strains of SARS-CoV-2 would assist in the make-up of the vaccine ingredients and measurement of the mutational densities in synonymous and non-synonymous mutant strains.

There is good news about the emergency use authorizations (EUAs) of COVID-19 vaccines sponsored by the Pfizer/BioNTech, Moderna, and AztraZeneca. The U.S.-FDA has recently approved some new recombinant protein-based, non-replicating subunit RNA vaccines against COVID-19. So far, the Phase 3 clinical trial results show that these vaccines can be safe and effective for use. However, this is EUA and not a full approval. According to the FDA [76] , EUA is given when adequate and approved alternatives are unavailable; it does not mean these vaccines are completely risk-free.

It is believed that the current demanding COVID-19 situations in places like the United States and some parts of the Europe had called for the emergency authorization. Many questions in association with these vaccines are yet unanswered. It is reasonable to accept that there are potential risks and fears of unknown regarding these new vaccines. But making these vaccines hastily available faster than the usual process should be less contemplated against the risk of infection with COVID-19 itself. However, it is believed that when productions of these vaccines increase and become more readily available and when many populations are vaccinated, there could be possible emergence of unknowns at any time. These unknowns will prompt scientists to continue to ask questions. It is important that some of the puzzles about emergency use of COVID-19 vaccines be brought to the limelight of discussion, especially now that there seem to be inadequate time to follow-up with the trial participants before the emergency approval. Now that vaccination already kick started, how long will the vaccine protection last? From participant recruitment to FDAemergency approval, the process of clinical trials of these vaccines took less than 6 months. Therefore, it is believed that there were no adequate follow-ups to answer this question. Similarly, there is no current available data to understand whether the vaccines will require booster shots and the perfect time these might be expected.

Besides, the main goal of COVID-19 vaccines is to prevent personal infection. Then, will the vaccinated individuals still prevent the spread of SARS-CoV-2 virus to non-vaccinated individuals? Even with the high level of assurance being provided by the vaccine companies regarding their efficacies (especially the mRNA vaccines) against all forms of SARS-CoV-2 mutant strains, it remains to be acknowledged whether the vaccinated individuals can still spread the infection or not. While in the present situations, it may be virtually impossible to vaccinate everyone due to the logistic and economic reasons, this question demands immediate answer in containment operations.

In addition, the available vaccines data did not provide information regarding effectiveness of the vaccines in specific groups of people such as asymptomatics, immunocompromised, previously infected individuals, pediatrics, pregnant, and breastfeeding women, among many others. It is important to note that "efficacy" in clinical trials is not tantamount to "effectiveness" in clinical applications to all population groups. As at the time of writing this report, none of the clinical trials have answered questions regarding these specific individuals, yet they were so listed in their exclusion criteria in clinical trial statement [77] .

Furthermore, with the euphoria of arrival of the first COVID-19 vaccines, the virus seems to continue "re-strategizing" its battle with the emergence of new mutant strains, rapidly spreading, and affecting younger populations [78] . Now that we have emergency vaccine available, can the people infected with the new variants (such as UK-20B/501Y.V1 and South African-20C/501Y.V2 strains) be protected? The answers we seek to these questions would be very germane to human safety and in addressing the global threats of COVID-19 disease that has affected socioeconomic well-being in many parts of the world.

Detailed information about the biology of SARS-CoV-2 is currently unknown. However, more information on the ecology of the virus is now in the limelight. The problem of SARS-CoV-2 rapid mutations is an emerging area of concern demanding urgent consideration in clinical trials and patient management. Vaccines usually become ineffective when a virus mutates. Likewise, drug resistance ensues when the genetic component of a virus is unstable. Ongoing clinical trials and current patient management on COVID-19 would achieve landmark success if the following are considered: (i) Improved rapid, sensitive and accurate diagnostics and development of a standard test, (ii) addressing the constant evolution of SARS-CoV-2 mutant strains, (iii) addressing the problem of immunoglobulin specificity prospectively, and (iv) Improving antiviral combination strategy against emerging genetic variability.

WHO Statement Regarding Cluster of Pneumonia Cases in Wuhan, China. Geneva: World Health Organization

World Health Organization. Coronavirus Disease (COVID-19) Pandemic: Coronavirus Disease (COVID-19) Outbreak Situation. Geneva: World Health Organization

A Human Monoclonal Antibody Blocking SARS-CoV-2 Infection

Clinical Trials on Drug Repositioning for COVID-19 Treatment

Drug Repurposing Approach to Fight COVID-19

An International Randomized Trial of Additional Treatments for COVID-19 in Hospitalized Patients Who are All Receiving the Local Standard of Care WHO-Solidarity-Germany

A Review on Current Repurposing Drugs for the Treatment of COVID-19: Reality and Challenges

Efficacy 1 of Pragmatic Same-day COVID-19 Ring Prophylaxis for Adult Individuals Exposed to SARS-CoV-2 in Switzerland (COPEP)

Artesunate: Could be an Alternative Drug to Chloroquine in COVID-19 Treatment

Repurposing Antimalarials to Tackle the COVID-19 Pandemic

Evaluating the Efficacy of Artesunate in Adults with Mild Symptoms of COVID-19

Drug Trials Snapshots: Artesunate. Silver Spring, MA: U.S. Food and Drug Administration

Chloroquine is a Potent Inhibitor of SARS Coronavirus Infection and Spread

A Review on Possible Modes of Action of Chloroquine/Hydroxychloroquine: Repurposing against SAR-CoV-2 (COVID-19) Pandemic

Chloroquine Phosphate Prophylactic Use in Health Personnel Exposed to COVID-19 Patients

Norwegian Coronavirus Disease 2019 Study (NO COVID-19)

A Multi-centre Open-label Two-arm Randomised Superiority Clinical Trial of Azithromycin Versus Usual Care in Ambulatory COVID-19: Study Protocol for the ATOMIC2 Trial

A Multicentre Openlabel Two-arm Randomised Superiority Clinical Trial of Azithromycin Versus Usual Care in Ambulatory COVID-19 (ATOMIC2) (ATOMIC2)

Azithromycin for COVID-19: More than just an Antimicrobial?

Meta-Analysis of the Adverse Effects of Long-term Azithromycin Use in Patients with Chronic Lung Diseases

Bevacizumab in Severe or Critical Patients with COVID-19 Pneumonia (BEST-CP)

Evaluation of the Efficacy and Safety of Sarilumab in Hospitalized Patients with COVID-19

Indian Costus, Quinine, Anise Seed, Deglycyrrhizinated Licorice, Artemisinin, Febrifugine on Immunity of Patients with (COVID-19)

1 Antioxidant Therapy for COVID-19 Study (GSHSOD-COVID)

Harmful effects of antioxidant therapy

N-acetyl Cysteine: RX List

Off-label" use of Hydroxychloroquine, Azithromycin, Lopinavir-Ritonavir and Chloroquine in COVID-19: A Survey of Cardiac Adverse Drug Reactions by the French Network of Pharmacovigilance Centers

Reply to Gautret et al: Hydroxychloroquine Sulfate and Azithromycin for COVID-19: What is the Evidence and what are the Risks?

A Bayesian Reanalysis of the Effects of Hydroxychloroquine and Azithromycin on Viral Carriage in Patients with COVID-19

Incidence of Adverse Drug Reactions in COVID-19 Patients in China: An Active Monitoring Study by Hospital Pharmacovigilance System

Triple Combination of Interferon Beta-1b, Lopinavir-Ritonavir, and Ribavirin in the Treatment of Patients Admitted to Hospital with COVID-19: An Open-label, Randomised, Phase 2 Trial

Diagnosis, Prevention, and Management of Statin Adverse Effects and Intolerance: Canadian Consensus Working Group Update (2016)

Darunavir and Cardiovascular Risk: Evaluating the Data to Inform Clinical Care

Comparative Effectiveness and Safety of Ribavirin Plus Interferon-Alpha, Lopinavir/Ritonavir Plus Interferon-Alpha and Ribavirin Plus Lopinavir/Ritonavir Plus Interferon-Alpha in Patients with Mild to Moderate Novel Coronavirus Pneumonia: Results of a Randomized, Open-Labeled Prospective Study

Remdesivir for 5 or 10 Days in Patients with Severe COVID-19

Vaccines for SARS-CoV-2: Lessons from Other Coronavirus Strains

News Feature: Avoiding Pitfalls in the Pursuit of a COVID-19 Vaccine

Emerging Neuropathological and Acidbase Disorders in Coronavirus Disease-19: A Close Look at Diagnostic Prospect in Containment Operations

The Effect of Control Strategies to Reduce Social Mixing on Outcomes of the COVID-19 Epidemic in Wuhan, China: A Modelling Study

COVID-19: A Novel Zoonotic Disease Caused by a Coronavirus from China: What we know and what we don't

Probable Pangolin Origin of 2019-nCoV Associated with Outbreak of COVID-19

Identifying SARS-CoV-2 Related Coronaviruses in Malayan Pangolins

Report of the WHO-China Joint Mission on Coronavirus Disease

World Health Organization

COVID-19 Public Health Threats and the Associated Myths: Assessment of the Level of Scientific Evidence against Misinformation Conflict and Conspiracy Theories

Characteristics of and Important Lessons from the Coronavirus Disease 2019 (COVID-19) Outbreak in China: Summary of a Report of 72 314 Cases from the Chinese Center for Disease Control and Prevention

Early Stage Nonclinical Pulmonary Disorder in COVID-19 May Present Asymptomatic and Fuel the Contagion

Spike Mutation Pipeline Reveals the Emergence of a More Transmissible Form of SARS-CoV-2

Interpreting Diagnostic Tests for SARS-CoV-2

Estimating False-negative Detection Rate of SARS-CoV-2 by RT-PCR

Test for COVID-19 Antibodies: The Importance of Sensitivity, Specificity and Predictive Powers

False-negative Results of Initial RT-PCR Assays for COVID-19: A Systematic Review

Variation in False-Negative Rate of Reverse Transcriptase Polymerase Chain Reaction-Based SARS-CoV-2 Tests by Time Since Exposure

Temporal Profiles of Viral Load in Posterior Oropharyngeal Saliva Samples and Serum Antibody Responses during Infection by SARS-CoV-2: An Observational Cohort Study

Serology Characteristics of SARS-CoV-2 Infection Since Exposure and Post Symptom Onset

Antiviral Therapy in Management of COVID-19: A Systematic Review on Current Evidence

A Trial of Lopinavir-Ritonavir in Adults Hospitalized with Severe Covid-19

Lopinavir/Ritonavir: A Review of its Use in the Management of HIV Infection

Current Pharmacological Treatments for COVID-19: What's Next?

Broad Spectrum Antiviral GS-5734 Inhibits Both Epidemic and Zoonotic Coronaviruses

FDA's approval of Veklury (Remdesivir) for the Treatment of COVID-19-The Science of Safety and Effectiveness

Neutralizing Antibody Treatment for COVID-19: Bamlanivimab

Systematic Approaches towards the Development of Host-Directed Antiviral Therapeutics

The Global Phosphorylation Landscape of SARS-CoV-2 Infection

Highdose Intravenous Immunoglobulin as a Therapeutic Option for Deteriorating Patients with Coronavirus Disease

Effect of Regular Intravenous Immunoglobulin Therapy on Prognosis of Severe Pneumonia in Patients with COVID-19

Could Intravenous Immunoglobulin Collected from Recovered Coronavirus Patients Protect against COVID-19 and Strengthen the Immune System of New Patients?

Human Monoclonal Antibodies Block the Binding of SARS-CoV-2 Spike Protein to Angiotensin Converting Enzyme 2 Receptor

Positive RT-PCR Test Results in Patients Recovered from COVID-19

Covid-19: WHO and South Korea Investigate Reconfirmed Cases

Roadmap to Developing a Recombinant Coronavirus S Protein Receptor-Binding Domain Vaccine for Severe Acute Respiratory Syndrome

Mutation Density Changes in SARS-CoV-2 are Related to the Pandemic Stage but to a Lesser Extent in the Dominant Strain with Mutations in Spike and RdRp

FDA Takes Key Action in Fight against COVID-19 by Issuing Emergency Use Authorization for First COVID-19 Vaccine

Study to Describe the Safety, Tolerability, Immunogenicity, and Efficacy of RNA Vaccine Candidates against COVID-19 in Healthy Individuals, Identifier No. NCT04368728

Authorization of the First COVID-19 Emergency Vaccines: The Matters Arising

Not applicable.

The authors declare that they have no competing interests.

No financial support or sponsorship received on this project.

Not applicable.

All authors have contributed to the information or material submitted for publication and have read and approved the manuscript. The authors have no direct or indirect commercial financial incentive or individual person's data in any form associated with publishing the manuscript.

KAA conceived the study and wrote the first draft together with AOO and MSR. The final copy was edited by LOO, KAA and AOO with updated information. KAA, LOO, and RTK designed the images, JOM and SAN supplied some useful resources with suggestions. All authors were involved in the literature search. KAA, AOO and LOO revised the manuscript. All authors read and approved the final manuscript.