Delta Lineage Research Articles

SARS-CoV-2 outbreak in lions, tigers and hyenas at Denver Zoo.

In late 2019, SARS-CoV-2 spilled-over from an animal host into humans, where it efficiently spread, resulting in the COVID-19 pandemic. Through both natural and experimental infections, we learned that many animal species are susceptible to SARS-CoV-2. Importantly, animals in close proximity to humans, including companion, farmed, and those at zoos and aquariums, became infected, and many studies demonstrated transmission to/from humans in these settings. In this study, we first review the literature of SARS-CoV-2 infections in tigers and lions, and compare species, sex, age, virus and antibody detection assay, and types, frequency and length of clinical signs, demonstrating broad heterogeneity amongst infections. We then describe a SARS-CoV-2 outbreak in lions, tigers and hyenas at Denver Zoo in late 2021. Animals were tested for viral RNA (vRNA) for four months. Lions had significantly more viral RNA in nasal swabs than both tigers and hyenas, and many individual lions experienced viral recrudescence after weeks of undetectable vRNA. Infectious virus was correlated with high levels of vRNA and was more likely to be detected earlier during infection. Four months post-infection, all tested animals generated robust neutralizing antibody titers. Animals were infected with Delta lineage AY.20 identical to a variant circulating at less than 1% in Colorado humans at that time, suggesting a single spillover event from an infected human spread within and between species housed at the zoo. Better understanding of epidemiology and susceptibility of SARS-CoV-2 infections in animals is critical to limit the current and future spread and protect animal and human health.

Molecular Characterization and Genomic Surveillance of SARS-CoV-2 Lineages in Central India.

Since the first reported case of COVID-19 in December 2019, several SARS-CoV-2 variants have evolved, and some of them have shown higher transmissibility, becoming the prevalent strains. Genomic epidemiological investigations into strains from different time points, including the early stages of the pandemic, are very crucial for understanding the evolution and transmission patterns. Using whole-genome sequences, our study describes the early landscape of SARS-CoV-2 variants in central India retrospectively (including the first known occurrence of SARS-CoV-2 in Madhya Pradesh). We performed amplicon-based whole-genome sequencing of randomly selected SARS-CoV-2 isolates (n = 38) collected between 2020 and 2022 at state level VRDL, ICMR-NIRTH, Jabalpur, from 11899 RT-qPCR-positive samples. We observed the presence of five lineages, namely B.1, B.1.1, B.1.36.8, B.1.195, and B.6, in 19 genomes from the first wave cases and variants of concern (VOCs) lineages, i.e., B.1.617.2 (Delta) and BA.2.10 (Omicron) in the second wave cases. There was a shift in mutational pattern in the spike protein coding region of SRAS-CoV-2 strains from the second wave in contrast to the first wave. In the first wave of infections, we observed variations in the ORF1Ab region, and with the emergence of Delta lineages, the D614G mutation associated with an increase in infectivity became a prominent change. We have identified five immune escape variants in the S gene, P681R, P681H, L452R, Q57H, and N501Y, in the isolates collected during the second wave. Furthermore, these genomes were compared with 2160 complete genome sequences reported from central India that encompass 109 different SARS-CoV-2 lineages. Among them, VOC lineages Delta (28.93%) and Omicron (56.11%) were circulating predominantly in this region. This study provides useful insights into the genetic diversity of SARS-CoV-2 strains over the initial course of the COVID-19 pandemic in central India.

Intranasal parainfluenza virus-vectored vaccine expressing SARS-CoV-2 spike protein of Delta or Omicron B.1.1.529 induces mucosal and systemic immunity and protects hamsters against homologous and heterologous challenge.

The continuous emergence of new SARS-CoV-2 variants requires that COVID vaccines be updated to match circulating strains. We generated B/HPIV3-vectored vaccines expressing 6P-stabilized S protein of the ancestral, B.1.617.2/Delta, or B.1.1.529/Omicron variants as pediatric vaccines for intranasal immunization against HPIV3 and SARS-CoV-2 and characterized these in hamsters. Following intranasal immunization, these B/HPIV3 vectors replicated in the upper and lower respiratory tract and induced mucosal and serum anti-S IgA and IgG. B/HPIV3 expressing ancestral or B.1.617.2/Delta-derived S-6P induced serum antibodies that effectively neutralized SARS-CoV-2 of the ancestral and B.1.617.2/Delta lineages, while the cross-neutralizing potency of B.1.1.529/Omicron S-induced antibodies was lower. Despite the lower cross-neutralizing titers induced by B/HPIV3 expressing S-6P from B.1.1.529/Omicron, a single intranasal dose of all three versions of B/HPIV3 vectors was protective against matched or heterologous WA1/2020, B.1.617.2/Delta or BA.1 (B.1.1.529.1)/Omicron challenge; hamsters were protected from challenge virus replication in the lungs, while low levels of challenge virus were detectable in the upper respiratory tract of a small number of animals. Immunization also protected against lung inflammatory response after challenge, with mild inflammatory cytokine induction associated with the slightly lower level of cross-protection of WA1/2020 and B.1.617.2/Delta variants against the BA.1/Omicron variant. Serum antibodies elicited by all vaccine candidates were broadly reactive against 20 antigenic variants, but the antigenic breadth of antibodies elicited by B/HPIV3-expressed S-6P from the ancestral or B.1.617.2/Delta variant exceeded that of the S-6P B.1.1.529/Omicron expressing vector. These results will guide development of intranasal B/HPIV3 vectors with S antigens matching circulating SARS-CoV-2 variants.

Emergence and fixation of SARS-CoV-2 minority variants in a chronically infected patient receiving therapy in Denmark.

SARS-CoV-2 variants of concern (VOC), such as Delta and Omicron have harbored mutations, which increased viral infectivity or ability to evade neutralizing antibodies. Immunocompromised patients might be a source of some of these emerging variants. In this study, we sequenced 17 consecutive samples from an immunocompromised patient with a long-term SARS-CoV-2 infection with the pre-VOC era lineage B.1.177.35. We here describe the emergence of 73 nonsynonymous minority variants in this patient and show that 10 of these mutations became dominant in the viral population during the treatment period. Four of these were seen throughout the infection period and had a very low global prevalence, although three of them were also observed later in the Alpha, Delta, and Omicron lineages. We also found that two adjacent nsp12 variants (M785I and S786P) belonged to different quasi-species and competed during the early stages of infection and remdesivir administration. This emphasizes the importance of ongoing genome surveillance of SARS-CoV-2 among immunocpromised patients.

Detection of co-infection and recombination cases with Omicron and local Delta variants of SARS-CoV-2 in Vietnam

The first nationwide outbreak of COVID-19 in Vietnam started in late April 2021 and was caused almost exclusively by a single Delta lineage, AY.57. In early 2022, multiple Omicron variants co-circulated with Delta variants and quickly became dominant. The co-circulation of Delta and Omicron happened leading to possibility of co-infection and recombination events which can be revealed by viral genomic data. From January to October 2022, a total of 1028 viral RNA samples out of 4852 positive samples (Ct < 30) were sequenced by the long pooled amplicons method on Illumina platforms. All sequencing data was analysed by the workflow for SARS-CoV-2 on CLC genomics workbench and Illumina Dragen Covid application. Among those sequenced samples, we detected a case of Delta AY.57/Omicron BA.1 co-infection and two cases of infection with Delta AY.57/Omicron BA.2 recombinants which were nearly identical and had different epidemiological characteristics. Since the AY.57 lineage circulated almost exclusively in Vietnam, these results strongly suggest domestic events of co-infection and recombination. These findings highlight the strengths of genomic surveillance in monitoring the circulating variants in the community enabling rapid identification of viral changes that may affect viral properties and evolutionary events.

Tracking SARS-CoV-2 variants of concern in wastewater: an assessment of nine computational tools using simulated genomic data.

Wastewater-based surveillance (WBS) is an important epidemiological and public health tool for tracking pathogens across the scale of a building, neighbourhood, city, or region. WBS gained widespread adoption globally during the SARS-CoV-2 pandemic for estimating community infection levels by qPCR. Sequencing pathogen genes or genomes from wastewater adds information about pathogen genetic diversity, which can be used to identify viral lineages (including variants of concern) that are circulating in a local population. Capturing the genetic diversity by WBS sequencing is not trivial, as wastewater samples often contain a diverse mixture of viral lineages with real mutations and sequencing errors, which must be deconvoluted computationally from short sequencing reads. In this study we assess nine different computational tools that have recently been developed to address this challenge. We simulated 100 wastewater sequence samples consisting of SARS-CoV-2 BA.1, BA.2, and Delta lineages, in various mixtures, as well as a Delta-Omicron recombinant and a synthetic 'novel' lineage. Most tools performed well in identifying the true lineages present and estimating their relative abundances and were generally robust to variation in sequencing depth and read length. While many tools identified lineages present down to 1 % frequency, results were more reliable above a 5 % threshold. The presence of an unknown synthetic lineage, which represents an unclassified SARS-CoV-2 lineage, increases the error in relative abundance estimates of other lineages, but the magnitude of this effect was small for most tools. The tools also varied in how they labelled novel synthetic lineages and recombinants. While our simulated dataset represents just one of many possible use cases for these methods, we hope it helps users understand potential sources of error or bias in wastewater sequencing analysis and to appreciate the commonalities and differences across methods.

Decoding the paradox: Understanding Elevated Hospitalization and Reduced Mortality in SARS-CoV-2 Variants

Introduction and aim: SARS-CoV-2 outbreaks occur cyclically, aligning with winter when vitamin D levels are lowest, except after new variant outbreaks. Adequate vitamin D is crucial for robust immune function. Hypovitaminosis diminishes immune responses, increasing susceptibility to viral infections. The manuscript explores the discrepancy between increased SARS-CoV-2 hospitalizations and lower mortality. Method​: SARS-CoV-2 mutants, including Delta, BQ, and XBB Omicron lineages, developed immune evasion capabilities, reducing the effectiveness of COVID-19 vaccines and bivalent boosters. The failure of COVID-19 vaccines to prevent infections and spread to others, coupled with the immune evasion exhibited by mutant viruses, contributed to continued SARS-CoV-2 outbreaks. Interestingly, dominant new mutants, despite their increased transmissibility, have caused fewer deaths. This article scrutinizes the mentioned incongruity through an analysis of published data. Results: Achieving herd immunity and eradicating SARS-CoV-2 has proven elusive due to ongoing mutagenesis and immune evasion, leading to recurrent viral outbreaks. The failure to approve repurposed early therapies for COVID-19 by regulators, as well as misinformation and weak strategies undertaken by leading health authorities, exacerbated the situation. Repurposed agents, including vitamin D and ivermectin, have demonstrated high efficacy against SARS-CoV-2 from the beginning, and remain unaffected by mutations. Despite their cost-effectiveness and widespread availability, regulatory approval for these generic agents in COVID-19 treatment is pending. Conclusion: Regulators hesitated to approve cost-effective, repurposed generic agents primarily to safeguard the temporary approval status of COVID-19 vaccines and anti-viral agents under Emergency Use Authorization, which persists. This reluctance overlooked the opportunity to implement an integrated approach with repurposed agents alongside COVID-19 vaccines, potentially reducing hospitalizations and fatalities and preventing outbreaks; this led to the failure to eradicate SARS-CoV-2 and becoming endemic. It is imperative that regulators now reconsider approving affordable generics for SARS-CoV-2 to effectively control future viral outbreaks. Non-technical Importance (Lay Abstract) Adequate vitamin D levels significantly bolster the human immune system—deficiency compromises immune responses and increases susceptibility, particularly to viruses. While new SARS-CoV-2 mutations like Omicron are less severe, they are more infectious and adept at evading immunity from vaccines; thus, they offer a limited spectrum of protection and duration. Primary COVID-19 vaccines have reduced disease severity but have failed to prevent viral spread, contributing to outbreaks. Booster doses had little effect on the virus but caused immune paresis, thus increasing susceptibility to infections. Regulators should consider approving generic, repurposed agents like vitamin D and ivermectin as adjunct therapies to address this challenge and better prepare for future pandemics. Proactively integrating vitamin D supplementation to fortify the immune system can mitigate vital outbreaks, alleviate hospital burdens, and reduce healthcare costs.

Whole genome analysis reveals unique traits of SARS-CoV-2 in pediatric patients

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continues to challenge the global healthcare with emerging variants and higher infectivity as well as morbidities. This study investigated potential age-related variations through genomic characterization of the virus under common clinical settings. A cohort comprising 71 SARS-CoV-2 strains from both infected infants and accompanying adults, diagnosed via RT-PCR at a tertiary pediatric hospital and research center, underwent Illumina paired-end sequencing. The subsequent analysis involved standard genomic screening, phylogeny construction, and mutational analyses. The analyzed SARSCoV- 2 strains were compared with globally circulating variants. The overall distribution revealed 67.61 % Delta, 25.7 % Omicron, and 1 % either Kappa or Alpha variants. In 2021, Delta predominated at ∼ 94 %, with Alpha/Kappa accounting for around 5 %. However, in 2022, over 94 % of the samples were Omicron variants, signifying a substantial shift from Delta dominance. Delta variants constituted 69.5 % of infections in adults and 78.5 % in infants, while Omicron variants were responsible for 31 % of cases in infants and 18 % in adults. The Spike region harbored the majority of mutations, with T19R being the most prevalent mutation in the Delta lineage. Notably, the frequencies of this mutation varied between infants and adults. In Omicron samples, G142D emerged as the most prevalent mutation. Our dataset predominantly featured clade 21A and lineage B.1.617.2. This study underscores the differential clinical presentations and genomic characteristics of SARS-CoV-2 in pediatric patients and accompanying adults. Understanding the dynamic evolution of the SARS- CoV-2 in both pediatric and adults can help in strengthening prophylactic measures.

Relative frequency of genomic mutations in SARS-CoV-2 recovered from southern Brazilian cases of COVID-19 through the Gamma, Delta and Omicron waves

The presence of different mutations in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome can be related to changes in coronavirus disease (COVID-19) infection. Besides, these viral alterations associated with factors such as massive number of positive cases, vaccination and reinfections can be important in the viral evolution process. As well as, mutations found at low frequencies may have a more neutral action and consequently be less inclined to negative selection, facilitating their spread through the population. Related to that, we aimed to present mutations that are possibly relevant in the process of viral evolution found in 115 SARS-CoV-2 sequences from samples of individuals residing in the metropolitan region of Porto Alegre in the state of Rio Grande do Sul, Brazil. The genome from clinical samples was sequenced using High-Throughput Sequencing (HTS) and analyzed using a workflow to map reads and find variations/SNPs. The samples were separated into 3 groups considering the sample lineage. Of the total number of analyzed sequences, 35 were from the Gamma lineage, 35 from Delta and 45 from Omicron. Amino acid changes present in frequencies lower than 80% of the reads in the sequences were evaluated. 11 common mutations among the samples were found in the Gamma lineage, 1 in the ORF1ab gene, 7 in the S gene, 2 in the ORF6 gene and 1 in the ORF7a gene. While in the Delta lineage, a total of 11 mutations distributed in the ORF1ab, S, ORF7a and N genes, 2, 7, 1 and 1 mutation were found in each gene, respectively. And finally, in the Omicron, 16 mutations were identified, 2 in the ORF1ab gene, 12 in the S gene and 2 in the M gene. In conclusion, we emphasize that genomic surveillance can be a useful tool to assess how mutations play a key role in virus adaptation, and its process of susceptibility to new hosts showing the possible signs of viral evolution.

Development and Evaluation of an In-House Real-Time RT-PCR Targeting nsp10 Gene for SARS-CoV-2 Detection.

The emergence of SARS-CoV-2 mutations poses significant challenges to diagnostic tests, as these mutations can reduce the sensitivity of commonly used RT-PCR assays. Therefore, there is a need to design diagnostic assays with multiple targets to enhance sensitivity. In this study, we identified a novel diagnostic target, the nsp10 gene, using nanopore sequencing. Firstly, we determined the analytical sensitivity and specificity of our COVID-19-nsp10 assay. The COVID-19-nsp10 assay had a limit of detection of 74 copies/mL (95% confidence interval: 48-299 copies/mL) and did not show cross-reactivity with other respiratory viruses. Next, we determined the diagnostic performance of the COVID-19-nsp10 assay using 261 respiratory specimens, including 147 SARS-CoV-2-positive specimens belonging to the ancestral strain and Alpha, Beta, Gamma, Delta, Mu, Eta, Kappa, Theta and Omicron lineages. Using a LightMix E-gene RT-PCR assay as the reference method, the diagnostic sensitivity and specificity of the COVID-19-nsp10 assay were found to be 100%. The median Cp values for the LightMix E-gene RT-PCR and our COVID-19-nsp10 RT-PCR were 22.48 (range: 12.95-36.60) and 25.94 (range 16.37-36.87), respectively. The Cp values of the COVID-19-nsp10 RT-PCR assay correlated well with those of the LightMix E-gene RT-PCR assay (Spearman's ρ = 0.968; p < 0.0001). In conclusion, nsp10 is a suitable target for a SARS-CoV-2 RT-PCR assay.

Long COVID across SARS-CoV-2 variants, lineages, and sublineages

This prospective study aimed to determine the prevalence of long COVID in patients hospitalized for SARS-CoV-2 infection from March 2020 to July 2022 and assess the impact of different viral lineages. A total of 2,524 patients were followed up for 12months, with persistent symptoms reported in 35.2% at one month, decreasing thereafter. Omicron variant patients initially showed higher symptom intensity, but this trend diminished over time. Certain viral lineages, notably Delta lineages AY.126 and AY.43, and Omicron sublineages BA.1.17, BA.2.56, and BA.5.1, consistently correlated with more severe symptoms. Overall, long COVID prevalence and severity were similar across SARS-CoV-2 variants. Specific lineages may influence post-COVID sequelae persistence and severity.

Impacts of Vaccination and Severe Acute Respiratory Syndrome Coronavirus 2 Variants Alpha and Delta on Coronavirus Disease 2019 Transmission Dynamics in Four Metropolitan Areas of the United States.

To characterize Coronavirus Disease 2019 (COVID-19) transmission dynamics in each of the metropolitan statistical areas (MSAs) surrounding Dallas, Houston, New York City, and Phoenix in 2020 and 2021, we extended a previously reported compartmental model accounting for effects of multiple distinct periods of non-pharmaceutical interventions by adding consideration of vaccination and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) variants Alpha (lineage B.1.1.7) and Delta (lineage B.1.617.2). For each MSA, we found region-specific parameterizations of the model using daily reports of new COVID-19 cases available from January 21, 2020 to October 31, 2021. In the process, we obtained estimates of the relative infectiousness of Alpha and Delta as well as their takeoff times in each MSA (the times at which sustained transmission began). The estimated infectiousness of Alpha ranged from 1.1x to 1.4x that of viral strains circulating in 2020 and early 2021. The estimated relative infectiousness of Delta was higher in all cases, ranging from 1.6x to 2.1x. The estimated Alpha takeoff times ranged from February 1 to February 28, 2021. The estimated Delta takeoff times ranged from June 2 to June 26, 2021. Estimated takeoff times are consistent with genomic surveillance data.

Cross-protection induced by highly conserved human B, CD4+, and CD8+ T-cell epitopes-based vaccine against severe infection, disease, and death caused by multiple SARS-CoV-2 variants of concern.

The coronavirus disease 2019 (COVID-19) pandemic has created one of the largest global health crises in almost a century. Although the current rate of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections has decreased significantly, the long-term outlook of COVID-19 remains a serious cause of morbidity and mortality worldwide, with the mortality rate still substantially surpassing even that recorded for influenza viruses. The continued emergence of SARS-CoV-2 variants of concern (VOCs), including multiple heavily mutated Omicron sub-variants, has prolonged the COVID-19 pandemic and underscores the urgent need for a next-generation vaccine that will protect from multiple SARS-CoV-2 VOCs. We designed a multi-epitope-based coronavirus vaccine that incorporated B, CD4+, and CD8+ T- cell epitopes conserved among all known SARS-CoV-2 VOCs and selectively recognized by CD8+ and CD4+ T-cells from asymptomatic COVID-19 patients irrespective of VOC infection. The safety, immunogenicity, and cross-protective immunity of this pan-variant SARS-CoV-2 vaccine were studied against six VOCs using an innovative triple transgenic h-ACE-2-HLA-A2/DR mouse model. The pan-variant SARS-CoV-2 vaccine (i) is safe , (ii) induces high frequencies of lung-resident functional CD8+ and CD4+ TEM and TRM cells , and (iii) provides robust protection against morbidity and virus replication. COVID-19-related lung pathology and death were caused by six SARS-CoV-2 VOCs: Alpha (B.1.1.7), Beta (B.1.351), Gamma or P1 (B.1.1.28.1), Delta (lineage B.1.617.2), and Omicron (B.1.1.529). A multi-epitope pan-variant SARS-CoV-2 vaccine bearing conserved human B- and T- cell epitopes from structural and non-structural SARS-CoV-2 antigens induced cross-protective immunity that facilitated virus clearance, and reduced morbidity, COVID-19-related lung pathology, and death caused by multiple SARS-CoV-2 VOCs.

Immunogenicity and safety of varying dosages of a fifth-wave influenza A/H7N9 inactivated vaccine given with and without AS03 adjuvant in healthy adults

BackgroundHuman infections with the avian influenza A(H7N9) virus were first reported in China in 2013 and continued to occur in annual waves. In the 2016/2017 fifth wave, Yangtze River Delta (YRD) lineage viruses, which differed antigenically from those of earlier waves, predominated. MethodsIn this phase 2 double-blinded trial we randomized 720 adults ≥ 19 years of age to receive two injections of a YRD lineage inactivated A/Hong Kong/125/2017 fifth-wave H7N9 vaccine, given 21 days apart, at doses of 3.75, 7.5, and 15 µg of hemagglutinin (HA) with AS03A adjuvant and at doses of 15 and 45 µg of HA without adjuvant. ResultsTwo doses of adjuvanted vaccine were required to induce HA inhibition (HI) antibody titers ≥ 40 in most participants. After two doses of the 15 µg H7N9 formulation, given with or without AS03 adjuvant, the proportion achieving a HI titer ≥ 40 against the vaccine strain at 21 days after the second vaccination was 65 % (95 % CI, 57 %-73 %) and 0 % (95 % CI, 0 %-4%), respectively. Among those who received two doses of the 15 µg adjuvanted formulation the proportion with HI titer ≥ 40 at 21 days after the second vaccination was 76 % (95 % CI, 66 %-84 %) in those 19–64 years of age and 49 % (95 % CI, 37 %-62 %) in those ≥ 65 years of age. Responses to the adjuvanted vaccine formulations did not vary by HA content. Antibody responses declined over time and responses against drifted H7N9 strains were diminished. Overall, the vaccines were well tolerated but, as expected, adjuvanted vaccines were associated with more frequent solicited systemic and local adverse events. ConclusionsAS03 adjuvant improved the immune responses to an inactivated fifth–wave H7N9 influenza vaccine, particularly in younger adults, but invoked lower responses to drifted H7N9 strains. These findings may inform future influenza pandemic preparedness strategies.

Three distinct ORF1a recombinants of the SARS-CoV-2 Delta variant of concern

The ongoing COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the emergency of various lineages through mutations and recombination. In the Delta lineage, we identified recombination events in the ORF1a gene, which divided the Delta sublineages into three different genotypes (Delta R1-R3). The regional distributions of Delta R1 and Delta R2 were not correlated, indicating that recombination occurred early in the Delta outbreak. The impact of the ORF1a gene on SARS-CoV-2 transmission remains unclear; however, our findings suggest that recombination may have contributed to the evolution and global spread of the Delta lineage.

SARS-CoV-2 Nucleocapsid Protein Mutations Found in Switzerland Disrupt N-Gene Amplification in Commonly Used Multiplex RT-PCR Assay.

At the end of 2021, we observed an increase in N-gene target failures (NGTF) with the TaqPathTM COVID-19 CE-IVD RT-PCR Kit from Thermo Fisher Scientific (TaqPath). We subsequently used whole-genome sequencing (Oxford Nanopore Technology) to identify potential issues with N-gene PCR efficacy. Among 168,101 positive samples with a cycle threshold (CT) value <30 from August 2021 to May 2022, 194 specimens without N-gene amplification by PCR were identified (0.12%). Most NGTF samples originated from a wave of infection attributable to the Delta variant (B.1.617.2) and its sublineages. Sequencing revealed the nucleotide substitution G28922T (A217S) in 151 samples (88.8%). The substitution G215C, a hallmark mutation for Delta lineages, was concurrently present in all of these samples. Ten samples (5.9%) carried the deletion 28,913-28,918 (del214/215), eight samples (4.7%) the deletion 28,913-28,915 (del214) and one sample (0.6%) the deletion 28,892-28,930 (del207-219). Samples showing intact N-gene amplification by PCR lacked these specific mutations, but delayed-type amplification (i.e., partial or pNGTF) was attributable to the exclusive presence of A217S. As the N gene is a common target in many RT-PCR methods for SARS-CoV-2, an in-depth analysis of single-target failures using a combination with viral whole genome sequencing may allow for the identification of diagnostic flaws and eventual new variants.

Near complete genome sequences from Southern Vietnam revealed local features of genetic diversity and intergenerational changes in SARS- CoV-2 variants in 2020–2021

BackgroundSince its beginnings in 2019, the COVID-19 pandemic is still a problem of global medical concern. Southern Vietnam is one of the country's vast regions, including 20 provinces and the densely populated metropolis Ho Chi Minh City. A randomized retrospective study was performed to investigate the epidemiology and genetic diversity of COVID-19. Whole-genome sequencing of 126 SARS-CoV-2 samples collected from Southern Vietnam between January 2020 and December 2021 revealed the main circulating variants and their distribution.MethodsEpidemiological data were obtained from the Department of Preventive Medicine of the Vietnamese Ministry of Health. To identify circulating variants, RNA, extracted from 126 nasopharyngeal swabs of patients with suspected COVID-19 were sequenced on Illunina MiSeq to obtain near complete genomes SARS-CoV-2.ResultsDue to the effectiveness of restrictive measures in Vietnam, it was possible to keep incidence at a low level. The partial relaxation of restrictive measures, and the spread of Delta lineages, contributed to the beginning of a logarithmic increase in incidence. Lineages 20A-H circulated in Southern Vietnam during 2020. Spread of the Delta lineage in Southern Vietnam began in March 2021, causing a logarithmic rise in the number of COVID-19 cases.ConclusionsPandemic dynamics in Southern Vietnam feature specific variations in incidence, and these reflect the success of the restrictive measures put in place during the early stages of the pandemic.

Higher Levels of SARS-CoV-2 Genetic Variation in Immunocompromised Patients: A Retrospective Case-Control Study.

A severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection lasts longer in immunocompromised hosts than in immunocompetent patients. Prolonged infection is associated with a higher probability of selection for novel SARS-CoV-2 mutations, particularly in the spike protein, a critical target for vaccines and therapeutics. From December 2020 to September 2022, respiratory samples from 444 immunocompromised patients and 234 health care workers positive for SARS-CoV-2, diagnosed at 2 hospitals in Paris, France, were analyzed using whole-genome sequencing using Nanopore technology. Custom scripts were developed to assess the SARS-CoV-2 genetic diversity between the 2 groups and within the host. Most infections were SARS-CoV-2 Delta or Omicron lineages. Viral genetic diversity was significantly higher in infections of immunocompromised patients than those of controls. Minor mutations were identified in viruses sequenced from immunocompromised individuals, which became signature mutations for newer SARS-CoV-2 variants as the epidemic progressed. Two patients were coinfected with Delta and Omicron variants. The follow-up of immunocompromised patients revealed that the SARS-CoV-2 genome evolution differed in the upper and lower respiratory tracts. This study found that SARS-CoV-2 infection in immunocompromised patients is associated with higher genetic diversity, which could lead to the emergence of new SARS-CoV-2 variants with possible immune evasion or different virulence characteristics.

Effectiveness of BNT162b2 and ChAdOx1 against SARS-CoV-2 household transmission: a prospective cohort study in England.

The ability of SARS-CoV-2 vaccines to protect against infection and onward transmission determines whether immunisation can control global circulation. We estimated the effectiveness of Pfizer-BioNTech mRNA vaccine (BNT162b2) and Oxford AstraZeneca adenovirus vector vaccine (ChAdOx1) vaccines against acquisition and transmission of the Alpha and Delta variants in a prospective household study in England. Households were recruited based on adult purported index cases testing positive after reverse transcription-quantitative (RT-q)PCR testing of oral-nasal swabs. Purported index cases and their household contacts took oral-nasal swabs on days 1, 3 and 7 after enrolment and a subset of the PCR-positive swabs underwent genomic sequencing conducted on a subset. We used Bayesian logistic regression to infer vaccine effectiveness against acquisition and transmission, adjusted for age, vaccination history and variant. Between 2 February 2021 and 10 September 2021, 213 index cases and 312 contacts were followed up. After excluding households lacking genomic proximity (N=2) or with unlikely serial intervals (N=16), 195 households with 278 contacts remained, of whom 113 (41%) became PCR positive. Delta lineages had 1.53 times the risk (95% Credible Interval: 1.04 - 2.20) of transmission than Alpha; contacts older than 18 years old were 1.48 (1.20 - 1.91) and 1.02 (0.93 - 1.16) times more likely to acquire an Alpha or Delta infection than children. Effectiveness of two doses of BNT162b2 against transmission of Delta was 36% (-1%, 66%) and 49% (18%, 73%) for ChAdOx1, similar to their effectiveness for Alpha. Protection against infection with Alpha was higher than for Delta, 69% (9%, 95%) vs. 18% (-11%, 59%), respectively, for BNT162b2 and 24% (-41%, 72%) vs. 9% (-15%, 42%), respectively, for ChAdOx1. BNT162b2 and ChAdOx1 reduce transmission of the Delta variant from breakthrough infections in the household setting, although their protection against infection within this setting is low.

Evidence of SARS-CoV-2 infection and co-infections in stray cats in Brazil

The zoonotic virus SARS-CoV-2, which causes severe acute respiratory syndrome in humans (COVID-19), has been identified in cats. Notably, most positive cases were in cats that had close contact with infected humans, suggesting a role for humans in animal transmission routes. Previous studies have suggested that animals with immune depletion are more susceptible to SARS-CoV-2 infection. To date, there is limited evidence of SARS-CoV-2 infections in stray and free-range cats affected by other pathogens. In this study, we investigated infections caused by SARS-CoV-2, Leishmania spp., Toxoplasma gondii, Mycoplasma spp., Bartonella spp., Feline leukemia virus (FeLV), and Feline immunodeficiency virus (FIV) in stray cats from an urban park in Brazil during the COVID-19 pandemic. From February to September 2021, 78 mixed-breed cats were tested for SARS-CoV-2 and hemopathogens using molecular analysis at Américo Renné Giannetti Municipal Park, Belo Horizonte, Minas Gerais, Brazil. An enzyme-linked immunosorbent assay (ELISA) was used to detect IgG in T. gondii. None of the animals in this study showed any clinical signs of infections. The SARS-CoV-2 virus RNA was detected in 7.7 % of cats, and a whole virus genome sequence analysis revealed the SARS-CoV-2 Delta lineage (B.1.617.2). Phylogenetic analysis showed that SARS-CoV-2 isolated from cats was grouped into the sublineage AY.99.2, which matches the epidemiological scenario of COVID-19 in the urban area of our study. Leishmania infantum was detected and sequenced in 9 % of cats. The seroprevalence of T. gondii was 23.1 %. Hemotropic Mycoplasma spp. was detected in 7.7 % of the cats, with Mycoplasma haemofelis and Candidatus Mycoplasma haemominutum being the most common. Bartonella henselae and Bartonella clarridgeiae were detected in 38.5 % of the cats, FeLV was detected in 17,9 %, and none of the cats studied tested positive for FIV. This study reports, for the first time, the SARS-CoV-2 infection with whole-genome sequencing in stray cats in southeastern Brazil and co-infection with other pathogens, including Bartonella spp. and Feline leukemia virus. Our study observed no correlation between SARS-CoV-2 and the other detected pathogens. Our results emphasize the importance of monitoring SARS-CoV-2 in stray cats to characterize their epidemiological role in SARS-CoV-2 infection and reinforce the importance of zoonotic disease surveillance.