The latest Omicron BA.4 and BA.5 lineages are frowning toward COVID-19 preventive measures: A threat to global public health

Development of multiplex allele-specific RT-qPCR assays for differentiation of SARS-CoV-2 Omicron subvariants

Quick differentiation of current circulating variants and the emerging recombinant variants of SARS-CoV-2 is essential to monitor their transmissions. However, the widely applied gene sequencing method is time-consuming and costly especially when facing recombinant variants, because a large part or whole genome sequencing is required. Allele-specific reverse transcriptase real time RT-PCR (RT-qPCR) represents a quick and cost-effective method for SNP (single nucleotide polymorphism) genotyping and has been successfully applied for SARS-CoV-2 variant screening. In the present study, we developed a panel of 5 multiplex allele-specific RT-qPCR assays targeting 20 key mutations for quick differentiation of the Omicron subvariants (BA.1 to BA.5 and their descendants) and the recombinant variants (XBB.1 and XBB.1.5). Two parallel multiplex RT-qPCR reactions were designed to separately target the prototype allele and the mutated allele of each mutation in the allele-specific RT-qPCR assay. Optimal annealing temperatures, primer and probe dosage, and time for annealing/extension for each reaction were determined by multi-factor and multi-level orthogonal test. The variation of Cp (crossing point) values (ΔCp) between the two multiplex RT-qPCR reactions was applied to determine if a mutation occurs or not. SARS-CoV-2 subvariants and related recombinant variants were differentiated by their unique mutation patterns. The developed multiplex allele-specific RT-qPCR assays exhibited excellent analytical sensitivities (with limits of detection (LoDs) of 1.47-18.52 copies per reaction), wide linear detection ranges (109-100 copies per reaction), good amplification efficiencies (88.25 to 110.68%), excellent reproducibility (coefficient of variations (CVs) < 5% in both intra-assay and inter-assay tests), and good clinical performances (99.5-100% consistencies with Sanger sequencing). The developed multiplex allele-specific RT-qPCR assays in the present study provide an alternative tool for quick differentiation of the SARS-CoV-2 Omicron subvariants and their recombinant variants. KEY POINTS: • A panel of five multiplex allele-specific RT-qPCR assays for quick differentiation of 11 SARS-CoV-2 Omicron subvariants (BA.1, BA.2, BA.4, BA.5, and their descendants) and 2 recombinant variants (XBB.1 and XBB.1.5). • The developed assays exhibited good analytical sensitivities and reproducibility, wide linear detection ranges, and good clinical performances, providing an alternative tool for quick differentiation of the SARS-CoV-2 Omicron subvariants and their recombinant variants.

Effectiveness of a broad-spectrum bivalent mRNA vaccine against SARS-CoV-2 variants in preclinical studies

Vaccines utilizing modified messenger RNA (mRNA) technology have shown robust protective efficacy against SARS-CoV-2 in humans. As the virus continues to evolve in both human and non-human hosts, risk remains that the performance of the vaccines can be compromised by new variants with strong immune escape abilities. Here we present preclinical characterizations of a novel bivalent mRNA vaccine RQ3025 for its safety and effectiveness in animal models. The mRNA sequence of the vaccine is designed to incorporate common mutations on the SARS-CoV-2 spike protein that have been discovered along the evolutionary paths of different variants. Broad-spectrum, high-titer neutralizing antibodies against multiple variants were induced in mice (BALB/c and K18-hACE2), hamsters and rats upon injections of RQ3025, demonstrating advantages over the monovalent mRNA vaccines. Effectiveness in protection against several newly emerged variants is also evident in RQ3025-vaccinated rats. Analysis of splenocytes derived cytokines in BALB/c mice suggested that a Th1-biased cellular immune response was induced by RQ3025. Histological analysis of multiple organs in rats following injection of a high dose of RQ3025 showed no evidence of pathological changes. This study proves the safety and effectiveness of RQ3025 as a broad-spectrum vaccine against SARS-CoV-2 variants in animal models and lays the foundation for its potential clinical application in the future.

Tracking SARS-CoV-2 and its variants in wastewater in Tunisia

Wastewater-based genomic surveillance can improve community prevalence estimates and identify emerging variants of pathogens. Wastewater influents and treated effluents from six wastewater treatment plants (WWTPs) in Tunisia were analyzed between December 2021 and July 2022. Wastewater samples were analyzed with reverse transcription solid digital PCR (RT-sdPCR) and whole-genome sequencing to determine the amount of SARS-CoV-2 RNA and assign SARS-CoV-2 lineages. The virus variants detected in wastewater samples were compared with COVID-19 prevalence data. The quantitative results in wastewater influents revealed that viral RNA concentrations at the treatment plants corroborate with locally reported clinical cases and show an increase before the increment of clinically diagnosed new COVID-19 cases between April and July 2022. Delta and Omicron variants were identified in the Tunisian wastewater. Interestingly, the presence of variant BA.5 was detected in samples prior to its inclusion as a variant of concern (VOC) by the Tunisian National Health Authorities. SARS-CoV-2 was detected in wastewater effluents, indicating that the wastewater treatment techniques used in the majority of Tunisian WWTPs are inefficient in removing the virus traces. This study reports the first identification of SARS-CoV-2 VOCs in Tunisian wastewater samples.

COVID-19 genome surveillance: A geographical landscape and mutational mapping of SARS-CoV-2 variants in central India over two years

Reading the viral genome through whole genome sequencing (WGS) enables the detection of changes in the viral genome. The rapid changes in the SARS-CoV-2 viral genome may cause immune escape leading to an increase in the pathogenicity or infectivity. Monitoring mutations through genomic surveillance helps understand the amino acid changes resulting from the mutation. These amino acid changes, especially in the spike glycoprotein, may have implications on the pathogenicity of the virus by rendering it immune-escape. The region of Vidarbha in Maharashtra represents 31.6 % of the state's total area. It holds 21.3 % of the total population. In total, 7457 SARS-CoV-2 positive samples belonging to 16 Indian States were included in the study, out of which 3002 samples passed the sequencing quality control criteria. The metadata of 7457 SARS-CoV-2 positive samples included in the study was sourced from the Integrated Health Information Platform (IHIP). The metadata of 3002 sequenced samples, including the FASTA sequence, was submitted to the Global Initiative on Sharing Avian Influenza Data (GISAID) and the Indian biological data centre (IBDC). This study identified 104 different SARS-CoV-2 pango-lineages classified into 19 clades. We have also analysed the mutation profiles of the variants found in the study, which showed eight mutations of interest, including L18F, K417N, K417T, L452R, S477N, N501Y, P681H, P681R, and mutation of concern E484K in the spike glycoprotein region. The study was from November 2020 to December 2022, making this study the most comprehensive genomic surveillance of SARS-CoV-2 conducted for the region.

Clustering analysis for the evolutionary relationships of SARS-CoV-2 strains

To explore the differences and relationships between the available SARS-CoV-2 strains and predict the potential evolutionary direction of these strains, we employ the hierarchical clustering analysis to investigate the evolutionary relationships between the SARS-CoV-2 strains utilizing the genomic sequences collected in China till January 7, 2023. We encode the sequences of the existing SARS-CoV-2 strains into numerical data through k-mer algorithm, then propose four methods to select the representative sample from each type of strains to comprise the dataset for clustering analysis. Three hierarchical clustering algorithms named Ward-Euclidean, Ward-Jaccard, and Average-Euclidean are introduced through combing the Euclidean and Jaccard distance with the Ward and Average linkage clustering algorithms embedded in the OriginPro software. Experimental results reveal that BF.28, BE.1.1.1, BA.5.3, and BA.5.6.4 strains exhibit distinct characteristics which are not observed in other types of SARS-CoV-2 strains, suggesting their being the majority potential sources which the future SARS-CoV-2 strains' evolution from. Moreover, BA.2.75, CH.1.1, BA.2, BA.5.1.3, BF.7, and B.1.1.214 strains demonstrate enhanced abilities in terms of immune evasion, transmissibility, and pathogenicity. Hence, closely monitoring the evolutionary trends of these strains is crucial to mitigate their impact on public health and society as far as possible.

Structurally defined heparin octasaccharide domain for binding to SARS-CoV-2 Omicron BA.4/BA.5/BA.5.2 spike protein RBD

Heparin, a bio-molecule with the highest negative charge density, is pharmaceutically important to prevent SARS-CoV-2 infection due to its strong competitive binding to spike protein compared with cellular heparan sulfate, which was confirmed as a co-receptor for virus-host cell interaction. Hence, the refined structural characterization of heparin targeting viral protein-HS interaction was significant for developing antiviral pharmaceuticals. In our study, heparin oligomers (dp ≥ 4) were prepared using heparinase I. The affinity oligosaccharides binding to Omicron spike protein RBD were separated by affinity chromatography and size exclusion chromatography. HILIC-ESI-FTMS was used for chain mapping analysis. The basic building blocks were analyzed and the binding domain sequence was produced by Seq-GAG software and further measured by SAX chromatography. As results, heparin octasaccharide was found with significantly higher binding ability than hexasaccharide and tetrasaccharide, and the octasaccharide [ΔUA-GlcNS6S-GlcA-GlcNS6S-IdoA2S-GlcNS6S-IdoA2S-GlcNS6S] with 12 sulfate groups showed high binding to RBD. The mechanism of this structurally well-defined octasaccharide binding to RBD was further investigated by molecular docking. The affinity energy of optimal pose was -6.8 kcal/mol and the basic amino acid residues in RBD sequence (Arg403, Arg452, Arg493 and His505) were identified as the major contribution factor to interacting with sulfate/carboxyl groups on saccharide chain. Our study demonstrated that heparin oligosaccharide with well-defined structure could be potentially developed as anti-SARS-CoV-2 drugs.

Dynamic immune landscape in vaccinated-BA.5-XBB.1.9.1 reinfections revealed a 5-month protection-duration against XBB infection and a shift in immune imprinting

BACKGROUND

The impact of previous vaccination on protective immunity, duration, and immune imprinting in the context of BA.5-XBB.1.9.1 reinfection remains unknown.

METHODS

Based on a 2-year longitudinal cohort from vaccination, BA.5 infection and XBB reinfection, several immune effectors, including neutralizing antibodies (Nabs), antibody-dependent cellular cytotoxicity (ADCC), virus-specific T cell immunity were measured to investigate the impact of previous vaccination on host immunity induced by BA.5 breakthrough infection and BA.5-XBB.1.9.1 reinfection.

FINDINGS

In absence of BA.5 Nabs, plasma collected 3 months after receiving three doses of inactivated vaccine (I-I-I) showed high ADCC that protected hACE2-K18 mice from fatality and significantly reduced viral load in the lungs and brain upon BA.5 challenge, compared to plasma collected 12 months after I-I-I. Nabs against XBB.1.9.1 induced by BA.5 breakthrough infection were low at day 14 and decreased to a GMT of 10 at 4 months and 28% (9/32) had GMT ≤4, among whom 67% (6/9) were reinfected with XBB.1.9.1 within 1 month. However, 63% (20/32) were not reinfected with XBB.1.9.1 at 5 months post BA.5 infection. Interestingly, XBB.1.9.1 reinfection increased Nabs against XBB.1.9.1 by 24.5-fold at 14 days post-reinfection, which was much higher than that against BA.5 (7.3-fold) and WT (4.5-fold), indicating an immune imprinting shifting from WT to XBB antigenic side.

INTERPRETATION

Overall, I-I-I can provide protection against BA.5 infection and elicit rapid immune response upon BA.5 infection. Furthermore, BA.5 breakthrough infection effectively protects against XBB.1.9.1 lasting more than 5 months, and XBB.1.9.1 reinfection results in immune imprinting shifting from WT antigen induced by previous vaccination to the new XBB.1.9.1 antigen. These findings strongly suggest that future vaccines should target variant strain antigens, replacing prototype strain antigens.

FUNDING

This study was supported by R&D Program of Guangzhou National Laboratory (SRPG23-005), National Key Research and Development Program of China (2022YFC2604104, 2019YFC0810900), S&T Program of Guangzhou Laboratory (SRPG22-006), and National Natural Science Foundation of China (81971485, 82271801, 81970038), Emergency Key Program of Guangzhou Laboratory (EKPG21-30-3), Zhongnanshan Medical Foundation of Guangdong Province (ZNSA-2020013), and State Key Laboratory of Respiratory Disease (J19112006202304).

Knowledge, attitude and practices towards SARS-CoV-2 genetic mutations and emerging variants among the population in Bangladesh: a cross-sectional study

OBJECTIVES

The coronavirus is continuously mutating and creating new SARS-CoV-2 variants. Public awareness about SARS-CoV-2 mutation is essential for effective preventive measures. The present study aimed to assess the knowledge, attitude and practices (KAP) towards SARS-CoV-2 variants among the general population in Bangladesh.

DESIGN

We conducted this online survey between 9 April 2021 and 10 May 2021 using structured questionnaires to collect the information.

SETTING

We distributed the survey link among the participants from all 64 districts of Bangladesh using social media platforms.

PARTICIPANTS

A total of 1,090 respondents completed this survey. After careful evaluation, we excluded 18 responses due to partial or incomplete information, and 1,072 responses entered into the final analysis.

PRIMARY OUTCOME

The KAP of participants towards SARS-CoV-2 variants depends on their demographic backgrounds. Associations between demographic characteristics and the likelihood of having adequate KAP were estimated using adjusted logistic regressions.

RESULTS

Among the participants, 42% had a poor knowledge level, 4% had a low attitude level and 14% had a poor practice score. The average knowledge, attitude and practice score were 2.65, 4.194 and 4.464 on a scale of 5, respectively. Only 51.8% of the participants knew about mutant strains, and only 47.6% knew about the effectiveness of vaccines against new variants. The key factors associated with poor knowledge levels were educational levels, area of residence, geographic location, and concern regarding COVID-19. Sociodemographic factors for poor attitude levels were geographic location, vaccination and concern regarding COVID-19. The pivotal factors in determining poor practice scores were the residence area of people and concern regarding COVID-19.

CONCLUSIONS

The knowledge level and positive attitude are associated with better preventive measures against SARS-CoV-2 variants. Based on these findings, we recommended several awareness programmes on SARS-CoV-2 mutations and variants for the rural population in Bangladesh to increase overall awareness levels.

Impact of mutations defining SARS-CoV-2 Omicron subvariants BA.2.12.1 and BA.4/5 on Spike function and neutralization

Additional mutations in the viral Spike protein helped the BA.2.12.1 and BA.4/5 SARS-CoV-2 Omicron subvariants to outcompete the parental BA.2 subvariant. Here, we determined the functional impact of mutations that newly emerged in the BA.2.12.1 (L452Q, S704L) and BA.4/5 (Δ69-70, L452R, F486V, R493Q) Spike proteins. Our results show that mutation of L452Q/R or F486V typically increases and R493Q or S704L impair BA.2 Spike-mediated infection. In combination, changes of Δ69-70, L452R, and F486V contribute to the higher infectiousness and fusogenicity of the BA.4/5 Spike. L452R/Q and F486V in Spike are mainly responsible for reduced sensitivity to neutralizing antibodies. However, the combined mutations are required for full infectivity, reduced TMPRSS2 dependency, and immune escape of BA.4/5 Spike. Thus, it is the specific combination of mutations in BA.4/5 Spike that allows increased functionality and immune evasion, which helps to explain the temporary dominance and increased pathogenicity of these Omicron subvariants.

Unraveling the Dynamics of Omicron (BA.1, BA.2, and BA.5) Waves and Emergence of the Deltacton Variant: Genomic Epidemiology of the SARS-CoV-2 Epidemic in Cyprus (Oct 2021-Oct 2022)

Commencing in December 2019 with the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), three years of the coronavirus disease 2019 (COVID-19) pandemic have transpired. The virus has consistently demonstrated a tendency for evolutionary adaptation, resulting in mutations that impact both immune evasion and transmissibility. This ongoing process has led to successive waves of infections. This study offers a comprehensive assessment spanning genetic, phylogenetic, phylodynamic, and phylogeographic dimensions, focused on the trajectory of the SARS-CoV-2 epidemic in Cyprus. Based on a dataset comprising 4700 viral genomic sequences obtained from affected individuals between October 2021 and October 2022, our analysis is presented. Over this timeframe, a total of 167 distinct lineages and sublineages emerged, including variants such as Delta and Omicron (1, 2, and 5). Notably, during the fifth wave of infections, Omicron subvariants 1 and 2 gained prominence, followed by the ascendancy of Omicron 5 in the subsequent sixth wave. Additionally, during the fifth wave (December 2021-January 2022), a unique set of Delta sequences with genetic mutations associated with Omicron variant 1, dubbed "Deltacron", was identified. The emergence of this phenomenon initially evoked skepticism, characterized by concerns primarily centered around contamination or coinfection as plausible etiological contributors. These hypotheses were predominantly disseminated through unsubstantiated assertions within the realms of social and mass media, lacking concurrent scientific evidence to validate their claims. Nevertheless, the exhaustive molecular analyses presented in this study have demonstrated that such occurrences would likely lead to a frameshift mutation-a genetic aberration conspicuously absent in our provided sequences. This substantiates the accuracy of our initial assertion while refuting contamination or coinfection as potential etiologies. Comparable observations on a global scale dispelled doubt, eventually leading to the recognition of Delta-Omicron variants by the scientific community and their subsequent monitoring by the World Health Organization (WHO). As our investigation delved deeper into the intricate dynamics of the SARS-CoV-2 epidemic in Cyprus, a discernible pattern emerged, highlighting the major role of international connections in shaping the virus's local trajectory. Notably, the United States and the United Kingdom were the central conduits governing the entry and exit of the virus to and from Cyprus. Moreover, notable migratory routes included nations such as Greece, South Korea, France, Germany, Brazil, Spain, Australia, Denmark, Sweden, and Italy. These empirical findings underscore that the spread of SARS-CoV-2 within Cyprus was markedly influenced by the influx of new, highly transmissible variants, triggering successive waves of infection. This investigation elucidates the emergence of new waves of infection subsequent to the advent of highly contagious and transmissible viral variants, notably characterized by an abundance of mutations localized within the spike protein. Notably, this discovery decisively contradicts the hitherto hypothesis of seasonal fluctuations in the virus's epidemiological dynamics. This study emphasizes the importance of meticulously examining molecular genetics alongside virus migration patterns within a specific region. Past experiences also emphasize the substantial evolutionary potential of viruses such as SARS-CoV-2, underscoring the need for sustained vigilance. However, as the pandemic's dynamics continue to evolve, a balanced approach between caution and resilience becomes paramount. This ethos encourages an approach founded on informed prudence and self-preservation, guided by public health authorities, rather than enduring apprehension. Such an approach empowers societies to adapt and progress, fostering a poised confidence rooted in well-founded adaptation.

The WHO has declared the end of pandemic phase of COVID-19: Way to come back in the normal life

The coronavirus disease 2019 (COVID-19) pandemic has resulted in significant global mortality and morbidity affecting millions of lives. As healthcare authorities worldwide are still paying substantial attention to COVID-19, other diseases continue to cause more deaths than COVID-19. The decreasing number of COVID-19 cases and deaths indicates that the pandemic is close to the end. For effective pandemic management, healthcare facilities worldwide have established COVID-19 units and testing facilities, instituting infection prevention and control measures, and employing telehealth services. Healthcare professionals have identified some promising treatments for COVID-19; also, mass vaccinations have improved patient outcomes. Instead of COVID-19 as a pandemic, it is time to pay more attention to other diseases to lessen their impact on public health. Therefore, the World Health Organization (WHO) has declared the end of the pandemic phase of COVID-19 considering the current COVID-19 situation and our preparedness, past pandemic experience, and long pandemic impact on social and economic life on May 5, 2023. In this article, we briefly discussed the present challenges due to COVID-19, necessary precautions, and future directions to return to life as before COVID-19.

Efficacy of novel SARS-CoV-2 rapid antigen tests in the era of omicron outbreak

Following the outbreak of Omicron and its subvariants, many of the currently available rapid Ag tests (RATs) showed a decrease in clinical performance. In this study, we evaluated the clinical sensitivity of the SARS-CoV-2 Rapid Antigen Test 2.0 for nasopharyngeal swabs and SARS-CoV-2 Rapid Antigen Test 2.0 Nasal for nasal swabs in 56 symptomatic individuals by comparing the results between RATs, RT-PCR, Omicron RT-PCR, and whole-genome sequencing (WGS). Furthermore, sequences of the Omicron subvariants' spike proteins were subjected to phylogenetic analysis. Both novel RATs demonstrated a high sensitivity of up to 92.86%, (95% CI 82.71%- 98.02%), 94.23%, (95% CI 83.07%- 98.49%), and 97.95% (95% CI 87.76%- 99.89%) compared to the RT-PCR, Omicron RT-PCR, and WGS, respectively. The clinical sensitivity of RATs was at its highest when the Ct value was restricted to 15≤Ct<25, with a sensitivity of 97.05% for RdRp genes. The Omicron RT-PCR analysis revealed subvariants BA.4 or BA.5 (76.8%) and BA.2.75 (16.1%). Subsequently, the WGS analysis identified BA.5 (65.5%) as the dominant subvariant. Phylogenetic analysis of the spike protein of Omicron's subvariants showed a close relationship between BA.4, BA.5, and BA.2.75. These results demonstrated that SARS-CoV-2 Rapid Antigen Test 2.0 and SARS-CoV-2 Rapid Antigen Test 2.0 Nasal are considered useful and efficient RATs for the detection of SARS-CoV-2, particularly during the current Omicron subvariants wave.

The fourth vaccination with a non-SARS-CoV-2 variant adapted vaccine fails to increase the breadth of the humoral immune response

Escape mutations in the spike protein of SARS-CoV-2 are a major reason for Omicron breakthrough infections. After basal vaccination only very low titers of Omicron neutralizing antibodies are present. However, booster vaccinations induce higher titers against the Omicron variant. The neutralization of the Delta and Omicron variants by sera obtained 6 months after 3rd vaccination and 2 weeks or 6 months after 4th vaccination with a monovalent RNA vaccine (Spikevax) was analyzed. It was observed for the Omicron variant that 6 months after the fourth vaccination, the titer returns to the same very low neutralizing capacity as 6 months after the third vaccination. The Delta variant neutralizing capacity wanes with a comparable kinetic although the titers are higher as compared to the Omicron variant. This indicates that the fourth vaccination with a monovalent vaccine based on the ancestral isolate neither affects the kinetic of the waning nor the breadth of the humoral response.

Omicron variant evolution on vaccines and monoclonal antibodies

The severe acute respiratory syndrome coronavirus (SARS-CoV)-2 responsible for the global COVID-19 pandemic has caused almost 760 million confirmed cases and 7 million deaths worldwide, as of end-February 2023. Since the beginning of the first COVID-19 case, several virus variants have emerged: Alpha (B1.1.7), Beta (B135.1), Gamma (P.1), Delta (B.1.617.2) and then Omicron (B.1.1.529) and its sublineages. All variants have diversified in transmissibility, virulence, and pathogenicity. All the newly emerging SARS-CoV-2 variants appear to contain some similar mutations associated with greater "evasiveness" of the virus to immune defences. From early 2022 onward, several Omicron subvariants named BA.1, BA.2, BA.3, BA.4, and BA.5, with comparable mutation forms, have followed. After the wave of contagions caused by Omicron BA.5, a new Indian variant named Centaurus BA.2.75 and its new subvariant BA.2.75.2, a second-generation evolution of the Omicron variant BA.2, have recently been identified. From early evidence, it appears that this new variant has higher affinity for the cell entry receptor ACE-2, making it potentially able to spread very fast. According to the latest studies, the BA.2.75.2 variant may be able to evade more antibodies in the bloodstream generated by vaccination or previous infection, and it may be more resistant to antiviral and monoclonal antibody drug treatments. In this manuscript, the authors highlight and describe the latest evidences and critical issues have emerged on the new SARS-CoV-2 variants.

Risk evaluation and mitigation strategies for newly detected SARS-CoV-2 Omicron BF.7 subvariant: A brief report

Mutations of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are always going on. The pathogenic characteristics of a virus are influenced by mutations in the viral genome. Therefore, the recently identified Omicron BF.7 subvariant might harm humans. Here we aimed to evaluate the potential risks of this newly detected variant and identify possible mitigation strategies. The frequent mutation associated with SARS-CoV-2 makes it more concerning compared to other viruses. The Omicron variant of SARS-CoV-2 has unique changes in the structural amino acid. Thus, Omicron subvariants are different from other coronavirus variants in terms of viral spread, disease severity, vaccine neutralization capacity, and immunity evade. Moreover, Omicron subvariant BF.7 is an offspring of BA.4 and BA.5. Similar S glycoprotein sequences are present among BF.7, BA.4, and BA.5. There is a change in the R346T gene in the receptor binding site of Omicron BF.7 than other Omicron subvariants. This BF.7 subvariant has created a limitation in current monoclonal antibody therapy. Omicron has mutated since it emerged, and the subvariants are improving in terms of transmission as well as antibody evasion. Therefore, the healthcare authorities should pay attention to the BF.7 subvariant of Omicron. The recent upsurge may create havoc all of a sudden. Scientists and researchers across the world should monitor the nature and mutations of SARS-CoV-2 variants. Also, they should find ways to fight the current circulatory variants and any future mutations.

Comparative Performance Evaluation of Personal Protective Measures and Antiviral Agents Against SARS-CoV-2 Variants: A Narrative Review

Scientists identified SARS-CoV-2 in December 2019 in Wuhan city of China. Soon after its identification, Covid-19 spreads almost everywhere. The World Health Organization (WHO) declared the Covid-19 outbreak as a pandemic on March 11, 2020. Countries are facing multiple waves due to the different variants of the coronavirus. Personal preventive measures, vaccines, and antiviral drugs are the approaches to control Covid-19. However, these approaches are being implemented in different countries at different levels because of the availability of personal protective measures and antiviral agents. The objective of this study was to evaluate the effectiveness of practicing measures to fight the Covid-19 pandemic. Here we searched relevant literature from PubMed and Scopus using the keywords such as personal protective measures, antiviral agents, and vaccine effectiveness. According to the present findings, protective measures were found comparatively less effective. Nevertheless, these measures can be used to limit the spreading of Covid-19. Antiviral agents can reduce the hospitalization rate and are more effective than personal protective measures. The most effective strategy against Covid-19 is early vaccination or multiple vaccination dose. The respective authorities should ensure equal distribution of vaccines, free availability of antiviral drugs, and personal protective measure in poor and developing countries. We recommend more studies to describe the effectiveness of practicing preventive measures and antiviral agents against recent variants of the coronavirus.