PCR-HRM for Genomic Surveillance of SARS-CoV-2: A Variant Detection Tool in Côte d’Ivoire, West Africa

The rise of new viruses, like SARS-CoV-2 causing the COVID-19 outbreak, along with the return of antibiotic resistance in harmful bacteria, demands a swift and efficient reaction to safeguard the health and welfare of the global population. It is crucial to have effective measures for prevention, intervention, and monitoring in place to address these evolving and recurring risks, ensuring public health and international security. In countries with limited resources, utilizing recombinant mutation plasmid technology in conjunction with PCR-HRM could help differentiate the existence of novel variants. cDNA synthesis was carried out on 8 nasopharyngeal samples following viral RNA extraction. The P1 segment of the SARS-CoV-2 Spike S protein was amplified via conventional PCR. Subsequently, PCR products were ligated with the pGEM-T Easy vector to generate eight recombinant SARS-CoV-2 plasmids. Clones containing mutations were sequenced using Sanger sequencing and analyzed through PCR-HRM. The P1 segment of the S gene from SARS-CoV-2 was successfully amplified, resulting in 8 recombinant plasmids generated from the 231 bp fragment. PCR-HRM analysis of these recombinant plasmids differentiated three variations within the SARS-CoV-2 plasmid population, each displaying distinct melting temperatures. Sanger sequencing identified mutations A112C, G113T, A114G, G214T, and G216C on the P1 segment, validating the PCR-HRM findings of the variations. These mutations led to the detection of L452R or L452M and F486V protein mutations within the protein sequence of the Omicron variant of SARS-CoV-2. In summary, PCR-HRM is a vital and affordable tool for distinguishing SARS-CoV-2 variants utilizing recombinant plasmids as controls.

Contribution of Genomic Surveillance in the Detection and Monitoring of SARS-CoV-2 Variants during the 6 Pandemic Waves in the Central African Republic from 2020 to 2023

Objective: The COVID-19 pandemic has highlighted the need to strengthen diagnosis and genomic surveillance capacities. In 2021, Central African managed five waves of COVID-19 by integrating genomic surveillance into their health monitoring system. This study sought to report surveillance data from the National Laboratory of Clinical Biology and Public Health and describe the circulation of SARS-CoV-2 variants. Materials and Methods: This retrospective, descriptive observational study spans three years, from April 2020 to November 2023. It was conducted on a population of consenting volunteers from across the Central African Republic, who were tested using RT-PCR on nasopharyngeal samples. Data with sufficient information were obtained from the National Laboratory of Clinical Biology and Public Health (LNBCSP) databases. Sequencing was largely carried out at the National Institute of Biomedical Research (INRB) in Kinshasa until May 2023, and subsequently at the LNBCSP. Results and Discussion: Out of 97,864 RT-PCR tests performed, 9,764 were positive, resulting in a prevalence of 9.98%. The average age of the patients was 39.97 years ± 13.76, and the male-to-female sex ratio was 2.12. RT-PCR test positivity was significantly associated with age (p = 0.001), sex (p = 0.013) and clinical manifestations. Ten variants circulated during the five recorded waves, with Omicron (B.1.1.529), Delta (B.1.617.2) variants being predominant. Notably, the B.1.620 and B.640 variants were prominent during the second wave. Conclusion: This retrospective study provides key insights into the COVID-19 pandemic in the CAR. It identifies risk factors and details the circulation of various SARS-CoV-2 variants. Enhancing national genomic surveillance capacities would enable the country to better respond to future pandemic challenges.

Genomic Profile of SARS-COV-2 Associated with COVID-19 Outbreaks in N’Djamena, Chad

Background: SARS-CoV-2 has circulated worldwide with dramatic consequences. In Chad, we have no data reported of variants. The aim of this study was to identify the SARS-CoV-2 variants that circulated during the epidemic from 2020 to 2021. Methods: This is a cross-sectional, descriptive study carried out between 2020 and 2021. Samples from patients with suspected COVID-19 were tested in five laboratories in N’Djamena. One hundred quality samples of the positives were sequenced in Kinshasa using Oxford nanopore technologies minion and the Protocol Midnight SARS-CoV2. Data were processed using Excel version 16 software. Results: Of the 100 samples sequenced, 77 (77%) produced sequences, 23 (23%) did not. The genomic profiles were wild-type Wuhan and minor mutations (19A, 19B (A), 20A (B.1, B.2), 20B (AV.1), 20D (B.1.1.1 /C.36), 20C), variant of concern Alpha (20I), variant of concern Delta (21A/J), variant of interest Eta (21D), variant of concern Omicron (21K) and unclassified variant under surveillance (B.1.640). Of these variants, the maximums were detected in patients aged 26 - 35 with 30.26% and 25.26% in 36 - 45. However, 24.67% were in travelers and 75.32% in residents, 35.06% in those vaccinated against COVID-19 and 62.33% in non-vaccinates. The estimated case-fatality rate was 2.44% (107/4374). Conclusion: This work has provided preliminary data on COVID-19 and SARS-CoV-2 variants circulating during the 2020-2021 epidemics in Chad.

Chest computed tomography findings of the Omicron variants of SARS-CoV-2 with different cycle threshold values

BACKGROUND The Omicron variant of severe acute respiratory syndrome coronavirus 2(SARSCoV-2)mainly infects the upper respiratory tract.This study aimed to determine whether the probability of pulmonary infection and the cycle threshold(Ct)measured using the fluorescent polymerase chain reaction(PCR)method were related to pulmonary infections diagnosed via computed tomography(CT).AIM To analyze the chest CT signs of SARS-CoV-2 Omicron variant infections with different Ct values,as determined via PCR.METHODS The chest CT images and PCR Ct values of 331 patients with SARS-CoV-2Omicron variant infections were retrospectively collected and categorized into low(<25),medium(25.00-34.99),and high(≥35)Ct groups.The characteristics of chest CT images in each group were statistically analyzed.RESULTS The PCR Ct values ranged from 13.36 to 39.81,with 99 patients in the low,155 in the medium,and 77 in the high Ct groups.Six abnormal chest CT signs were detected,namely,focal infection,patchy consolidation shadows,patchy groundglass shadows,mixed consolidation ground-glass shadows,subpleural interstitial changes,and pleural changes.Focal infections were less frequent in the low Ct group than in the medium and high Ct groups;these infections were the most common sign in the medium and high Ct groups.Patchy consolidation shadows and pleural changes were more frequent in the low Ct group than in the other two groups.The number of patients with two or more signs was greater in the low Ct group than in the medium and high Ct groups.CONCLUSION The chest CT signs of patients with pulmonary infection caused by the Omicron variants of SARSCoV-2 varied depending on the Ct values.Identification of the characteristics of Omicron variant infection can help subsequent planning of clinical treatment.

Surveillance of emerging SARS-CoV-2 variants by nanopore technology-based genome sequencing

Objective:To surveill emerging variants by nanopore technology-based genome sequencing in different COVID-19 waves in Sri Lanka and to examine the association with the sample characteristics,and vaccination status.Methods:The study analyzed 207 RNA positive swab samples received to sequence laboratory during different waves.The N gene cut-off threshold of less than 30 was considered as the major inclusion criteria.Viral RNA was extracted,and elutes were subjected to nanopore sequencing.All the sequencing data were uploaded in the publicly accessible database,GISAID.Results:The Omicron,Delta and Alpha variants accounted for 58%,22%and 4%of the variants throughout the period.Less than 1%were Kappa variant and 16%of the study samples remained unassigned.Omicron variant was circulated among all age groups and in all the provinces.Ct value and variants assigned percentage was 100%in Ct values of 10-15 while only 45%assigned Ct value over 25.Conclusions:The present study examined the emergence,prevalence,and distribution of SARS-CoV-2 variants locally and has shown that nanopore technology-based genome sequencing enables whole genome sequencing in a low resource setting country.

Omicron variant (B.1.1.529) of SARS-CoV-2: Mutation, infectivity, transmission, and vaccine resistance

The appearance of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)variant Omicron(B.1.1.529)has caused panic responses around the world because of its high transmission rate and number of mutations.This review summarizes the highly mutated regions,the essential infectivity,transmission,vaccine breakthrough and antibody resistance of the Omicron variant of SARSCoV-2.The Omicron is highly transmissible and is spreading faster than any previous variant,but may cause less severe symptoms than previous variants.The Omicron is able to escape the immune system’s defenses and coronavirus disease 2019 vaccines are less effective against the Omicron variant.Early careful preventive steps including vaccination will always be key for the suppression of the Omicron variant.

CRISPR-Cas12a-Empowered Electrochemical Biosensor for Rapid and Ultrasensitive Detection of SARS-CoV-2 Delta Variant

Coronavirus disease 2019(COVID-19)is a highly contagious disease caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).The gold standard method for the diagnosis of SARS-CoV-2 depends on quantitative reverse transcription-polymerase chain reaction till now,which is time-consuming and requires expensive instrumentation,and the confirmation of variants relies on further sequencing techniques.Herein,we first proposed a robust technique-methodology of electrochemical CRISPR sensing with the advantages of rapid,highly sensitivity and specificity for the detection of SARS-CoV-2 variant.To enhance the sensing capability,gold electrodes are uniformly decorated with electro-deposited gold nanoparticles.Using DNA template identical to SARS-CoV-2 Delta spike gene sequence as model,our biosensor exhibits excellent analytical detection limit(50 fM)and high linearity(R2=0.987)over six orders of magnitude dynamic range from 100 fM to 10 nM without any nucleic-acid-amplification assays.The detection can be completed within 1 h with high stability and specificity which benefits from the CRISPR-Cas system.Furthermore,based on the wireless micro-electrochemical platform,the proposed biosensor reveals promising application ability in point-of-care testing.

Symptomatic COVID-19 in University Students: A School-Wide Web-Based Questionnaire Survey during the Omicron Variant Outbreak

Aim: To detect risk and preventive factors associated with the Omicron variant infection in university students, a combination of a web-based survey and multivariate logistic regression analysis was introduced as the front-line initiatives by the school health practitioners. Design: Questionnaire survey. Methods: The school-wide web-based questionnaire survey was conducted among our university students as a part of the annual health check-up in April, 2023. The positive outcome was confined to the first symptomatic COVID-19 onset during the Omicron variant outbreak. Results: In this self-administered survey, risk or protective associations were merely estimated statistically in university students (n = 5406). In measured factors, karaoke and club/group activities could maintain the statistical significance in adjusted odds ratios (ORs) as relative risk factors, and science course, measles/ rubella (MR) vaccination, and COVID-19 vaccination remained as relative protective factors in adjusted OR analyses. Club/group activities with member gathering and karaoke sing-along sessions in university students may frequently have WHO’s three Cs. These risk factors are still important topics for the infection control of COVID-19 in university students. Together with some recent reports from other researchers, the significant protective role of MR vaccine in our survey warrants further clinical investigation. If the breakthrough infection continuously constitutes the majority of infection, real data in test-negative case-control or web-based questionnaire design continue to be important for statistical analysis to determine the minimal requirement of our strategies which may be equivalent to or replace COVID-19 vaccines.

A Retrospective Analysis of Wastewater Confirms Dominant Circulation of SARS-CoV-2 Delta Variant in Nairobi, Kenya, between April 2021 and August 2021

Wastewater surveillance has been applied in various parts of the world to monitor the introduction and transmissions of SARS-CoV-2 variants in a population. The knowledge of SARS-CoV-2 variants circulating in a population is critical to COVID-19 management and timing of the application of public health countermeasures. Contrary to the routine clinical surveillance of SARS-CoV-2 where cases from asymptomatic patients are often underreported, wastewater surveillance offers an unbiased tool for monitoring the extent of SARS-CoV-2 transmissions in a community. The present study aimed to characterize SARS-CoV-2 variants that circulated in Nairobi County, Kenya, between April 2021 and August 2021 utilizing wastewater samples. Viral RNA was extracted from wastewater samples, followed by SARS-CoV-2 screening by real-time RT-qPCR before targeted sequencing of the Spike gene. Forty samples were analyzed, of which 50% (n = 20) tested positive for SARS-CoV-2 by real-time RT-qPCR. Of these, 45% (n = 9) were successfully amplified by RT-PCR and sequenced. The majority (78%, 7/9) of the viruses belonged to the Delta (B.1.617.2) lineage of SARS-CoV-2, while a minority (22%) belonged to the Alpha (B.1.1.7) and Alpha-Delta lineages. Phylogenetic analysis of the SARS-COV-2 delta lineage strains revealed scattered clustering of the Kenyan viruses among the global strains included in the analysis, suggesting different introductory routes into the country. On the whole, our results confirm previous clinical findings that SARS-CoV-2 variants belonging to the Alpha (B.1.1.7) and Delta (B.1.617.2) lineages circulated in Nairobi County, Kenya during the study period, with the latter predominating. This is the first study to describe the diversity of SARS-CoV-2 variants circulating in Kenya, through wastewater analysis.

Case series in Indonesia:B.1.617.2(delta)variant of SARS-CoV-2 infection after a second dose of vaccine

BACKGROUND The B.1.617.2(delta)variant of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)was first discovered in Maharashtra in late 2020 and has rapidly expanded across India and worldwide.It took only 2 mo for this variant to spread in Indonesia,making the country the new epicenter of the delta variant as of July 2021.Despite efforts made by accelerating massive rollouts of current vaccines to protect against infection,cases of fully-vaccinated people infected with the delta variant have been reported.AIM To describe the demographic statistics and clinical presentation of the delta variant infection after the second dose of vaccine in Indonesia.METHODS A retrospective,single-centre case series of the general consecutive population that worked or studied at Faculty of Medicine,Universitas Indonesia with confirmed Delta Variant Infection after a second dose of vaccine from 24 June and 25 June 2021.Cases were collected retrospectively based on a combination of author recall,reverse transcription-polymerase chain reaction(RT-PCR),and whole genome sequencing results from the Clinical Microbiology Laboratory,Faculty of Medicine,Universitas Indonesia.RESULTS Between 24 June and 25 June 2021,15 subjects were confirmed with the B.1.617.2(delta)variant infection after a second dose of the vaccine.Fourteen subjects were vaccinated with CoronaVac(Sinovac)and one subject with ChAdOx1 nCoV-19(Oxford-AstraZeneca).All of the subjects remained in home isolation,with fever being the most common symptom at the onset of illness(n=10,66.67%).The mean duration of symptoms was 7.73 d(±5.444).The mean time that elapsed from the first positive swab to a negative RT-PCR test for SARS-CoV-2 was 17.93 d(±6.3464).The median time that elapsed from the second dose of vaccine to the first positive swab was 87 d(interquartile range:86-128).CONCLUSION Although this case shows that after two doses of vaccine,subjects are still susceptible to the delta variant infection,currently available vaccines remain the most effective protection.They reduce clinical manifestations of COVID-19,decrease recovery time from the first positive swab to negative swab,and lower the probability of hospitalization and mortality rate compared to unvaccinated individuals.

New and Newer Vaccines for SARS-CoV-2 Variants. Are the Major Vaccine Developers on the Right Track, Or Is Delipidation the Answer?

Background: Global Covid-19 pandemic has led to remarkable scientific achievements resulting in the development and rapid implementation of vaccines towards the original wild-type SARS-CoV-2 virus. Most Covid-19 vaccines are targeted to only one protein (the Spike protein) on the virus. SARS-CoV-2 that causes Covid-19 naturally undergoes multiple mutations over time. Such mutations can be inconsequential or have dire consequences. The lack of effectiveness of current vaccines towards mutated variants of Covid-19 is of major concern. The objective of this study is to describe an optimal solvent system that creates, via delipidation, a non-synthetic, host-derived or nonhost-derived modified viral particle that has its lipid envelope removed, exposing hidden undenatured proteins from within the virus, that generate a positive immunologic response when administered into a host, thereby providing a vaccine that offers strong and broad protection against the virus. Methods: Lipid removal from viruses by specific procedures renders the exposure of hidden proteins. Protection by antibodies to all of the virus’ protein types has shown to be far superior to protection by antibodies that are created by a single protein type. Results: Published studies with the Hepatitis virus, Pestivirus and HIV virus have reported the wide range of applications with this delipidation approach resulting in effectively long-term and broad protection vaccines. Conclusion: Mutations are rendering existing vaccines less effective. New approaches to obtain a more permanent vaccine that minimizes the effects of mutation are obtainable by delipidation of the viral particle and thereby creating vaccines that are more permanent with broad protection.

Epidemiology of SARS-CoV-2 and Emergence of UK Variant in Zintan City of Libya

Introduction: Coronavirus Disease 2019 (COVID-19) is an infectious respiratory disease caused by SARS-CoV-2. The disease was first broke out in Wuhan City, Hubei Province, China and subsequently spread to all countries and was considered by WHO as a worldwide pandemic. This study is aimed to determine the epidemiology of SARS-CoV-2 and the presence of UK variants in Zintan city of Libya taking some risk factors into account. Methods: In a cross-sectional retrospective study, a total of 15486 nasopharyngeal swabs were collected from COVID-19 suspected patients, travelers and people need disease-free certificates for hospital admission, etc. The samples were collected during the period from August 2020 to June 2021 and tested using real-time RT-PCR (rRT-PCR) kits for SARS-CoV-2 and UK variants. Age groups, sex, and monthly weather were considered as risk factors. Results: The positivity rate of COVID-19 in Zintan city was estimated to be (3891;25.12%) for the period from August 2020 to June 2021. Females showed significantly (p < 0.05) higher positivity rate (2100;54%) as compared to males (1791;46%). Out of the 3891 positive cases, 52 were deceased. The Case Fatality Rate (CFR) was 1.33 recorded significantly in cases aged ≥ 65 years which was higher in males (56.66%) than females (43.33%). The peak of the first wave of infection was recorded in October 2020 (590;15.15%) whereas the peak of the second wave of infection was recorded in April 2021 (727;18.71%). The positivity rate was decreased as the temperature increased. UK variant is detected firstly in May 2021 with the percentage of 6.2% of tested samples. Conclusions: Health Authorities are encouraged to continue implementing the control measures during the decrease phase of infection to stop transmission of the virus in the next wave. Early detection of new variants and studying their genetic characteristics play a valuable role in prevention and control.

SARS-CoV-2 Omicron variant (B.1.1.529): A concern with immune escape

Omicron,the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)variant that is now spreading across the world,is the most altered version to emerge so far,with mutations comparable to changes reported in earlier variants of concern linked with increased transmissibility and partial resistance to vaccineinduced immunity.This article provides an overview of the SARS-CoV-2 variant Omicron(B.1.1.529)by reviewing the literature from major scientific databases.Although clear immunological and clinical data are not yet available,we extrapolated from what is known about mutations present in the Omicron variant of SARS-CoV-2 and offer preliminary indications on transmissibility,severity,and immune escape through existing research and databases.

Multi-omics analysis of attenuated variant reveals potential evaluation marker of host damaging for SARS-CoV-2 variants

SARS-CoV-2 continues to threaten human society by generating novel variants via mutation and recombination.The high number of mutations that appeared in emerging variants not only enhanced their immune-escaping ability but also made it difficult to predict the pathogenicity and virulence based on viral nucleotide sequences.Molecular markers for evaluating the pathogenicity of new variants are therefore needed.By comparing host responses to wild-type and variants with attenuated pathogenicity at proteome and metabolome levels,six key molecules on the polyamine biosynthesis pathway including putrescine,SAM,dc-SAM,ODC1,SAMS,and SAMDC were found to be differentially upregulated and associated with pathogenicity of variants.To validate our discovery,human airway organoids were subsequently used which recapitulates SARS-CoV-2 replication in the airway epithelial cells of COVID-19 patients.Using ODC1 as a proof-ofconcept,differential activation of polyamine biosynthesis was found to be modulated by the renin-angiotensin system(RAS)and positively associated with ACE2 activity.Further experiments demonstrated that ODC1 expression could be differentially activated upon a panel of SARS-CoV-2 variants of concern(VOCs)and was found to be correlated with each VOCs’pathogenic properties.Particularly,the presented study revealed the discriminative ability of key molecules on polyamine biosynthesis as a predictive marker for virulence evaluation and assessment of SARS-CoV-2 variants in cell or organoid models.Our work,therefore,presented a practical strategy that could be potentially applied as an evaluation tool for the pathogenicity of current and emerging SARS-CoV-2 variants.

SARS-CoV-2 variants are associated with different clinical courses in children with MIS-C

Background Recent infection with SARS‑CoV-2 in children has been associated with multisystem inflammatory syndrome in children(MIS-C).SARS‑CoV-2 has undergone different mutations.Few publications exist about specific variants and their correlation with the severity of MIS-C.Methods This was a single-center,retrospective study including all patients admitted with MIS-C at Rady Children’s Hospital-San Diego between May 2020 and March 2022.Local epidemiologic data,including viral genomic information,were obtained from public records.Demographics,clinical presentation,laboratory values,and outcomes were obtained from electronic medical records.Results The analysis included 104 pediatric patients.Four MIS-C waves were identified.Circulating variants in San Diego during the first wave included clades 20A to C.During the second wave,there were variants from clades 20A to C,20G,21C(Epsilon),20I(Alpha),and 20J(Gamma).The third wave had Delta strains(clades 21A,21I,and 21J),and the fourth had Omicron variants(clades 21K,21L,and 22C).MIS-C presented with similar symptoms and laboratory findings across all waves.More patients were admitted to the pediatric intensive care unit(PICU)(74%)and required inotropic support(63%)during the second wave.None of the patients required mechanical circulatory support,and only two required invasive ventilatory support.There was no mortality.Conclusions The various strains of SARS-CoV-2 triggered MIS-C with differing severities,with the second wave having a more severe clinical course.Whether the differences in disease severity across variants were due to changes in the virus or other factors remains unknown.

Development of T cell antigen-based human coronavirus vaccinesagainst nAb-escaping SARS-CoV-2 variants

Currently approved vaccines have been successful in preventing the severity of COVID-19 and hospitalization. These vaccines primarily induce humoral immune responses;however, highly transmissible and mutated variants, such as the Omicron variant, weaken the neutralization potential of the vaccines, thus,raising serious concerns about their efficacy. Additionally, while neutralizing antibodies(nAbs) tend to wane more rapidly than cell-mediated immunity, long-lasting T cells typically prevent severe viral illness by directly killing infected cells or aiding other immune cells. Importantly, T cells are more cross-reactive than antibodies, thus, highly mutated variants are less likely to escape lasting broadly cross-reactive T cell immunity. Therefore, T cell antigen-based human coronavirus(HCoV) vaccines with the potential to serve as a supplementary weapon to combat emerging SARS-CoV-2 variants with resistance to n Abs are urgently needed. Alternatively, T cell antigens could also be included in B cell antigen-based vaccines to strengthen vaccine efficacy. This review summarizes recent advancements in research and development of vaccines containing T cell antigens or both T and B cell antigens derived from proteins of SARS-CoV-2 variants and/or other HCo Vs based on different vaccine platforms.

A human monoclonal antibody neutralizes SARS-CoV-2 Omicron variants bytargeting the upstream region of spike protein HR2 motif

The continuous emergence of new severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)variants meansthere is a need to explore additional strategies to develop broad-spectrum vaccines or therapeutics for individuals remaining at risk of coronavirus disease 2019(COVID-19).Neutralizing monoclonal antibody(mAb)that binds to theconserved S2 subunit of the SARS-CoV-2 spike(S)protein alone,or in combination with mAb that binds to the receptor-binding domain(RBD)of S protein,might be effective in eliciting protection from infection by a variety of SARS-CoV2 variants.Using high-throughput single-cell immunoglobulin sequencing of B cells from COVID-19-convalescent donors,we identified a high-affinity S2-specific mAb-39,that could inhibit original SARS-CoV-2 strain,Omicron BA.1,BA.2.86,BA.4,BA.5,and EG.5.1 S protein-mediated membrane fusion,leading to the neutralization of these pseudoviralinfections.Moreover,mAb-39 could also improve the neutralizing activity of anti-RBD antibody against the highlyneutralization-resistant Omicron variants.Molecular docking and point mutation analyses revealed that mAb-39 recognized epitopes within the conserved upstream region of the heptad repeat 2(HR2)motif of the S2 subunit.Collectively,these findings demonstrate that targeting the conserved upstream region of the HR2 motif(e.g.,using mAbs)provides anovel strategy for preventing the infection of SARS-CoV-2 and its variants.

Gastrointestinal symptoms in patients with COVID-19: Is there a relationship with mortality and new variations of SARS-CoV-2?

Coronavirus disease 2019(COVID-19)is caused by the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Although,respiratory symptoms are typical the digestive system is also a susceptible target with gastrointestinal symptoms present even in the absence of respiratory symptoms.The gastrointestinal symptoms of COVID-19 include diarrhea,abdominal pain,anorexia,and nausea among other symptoms.Some questions that remain to be answered include:Do patients with gastrointestinal symptoms have a higher mortality?SARS-CoV-2 variants are already a global reality:Do these variants present with a greater prevalence of gastrointestinal symptoms?Do patients with these symptoms warrant more intensive care unit care?

Novel coronavirus"Omicron subtype variant strain BA.2":The latest research progress

Since the outbreak of COVID-19,with the emergence of a series of novel coronavirus variants of different types,COVID-19 has continued to spread across the globe,posing a huge threat to the lives and health of people around the world and posing a severe challenge to global public health security.Recently,the World Health Organization(WHO)announced that novel coronavirus variant strain"Omicron"subtype variant strain BA.2 has been found in 57 countries and regions.It has higher vaccine and antibody tolerance and is more infectious than omicron(B.1.1.529).In this paper,we briefly review the recent studies on the omicron subtype variant strain BA.2.

Research progress on the correlation between immunosuppressive population and SARS-CoV-2 variation

Recently,some severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)variants represented by B.1.7(Alpha),B.1.351(Beta),P1(Gamma),B.1.617(Delta)and B.1.529(Omicron)have higher transmission and pathogenicity.Especially,Omicron causes global panic because of its high mutation in infectivity and vaccine escape,and their emergence makes the epidemic more difficult to control.The latest research reports indicate that these new corona mutants may first be mutated in the special population of immunosuppressive patients,and long-term infection and artificial immunotherapy may promote the variation of SARS-CoV-2.Not only that,there are a large number of congenital or acquired immunosuppressive patients worldwide,and immunosuppressive patients infected with SARS-CoV-2 will also have different impacts on social public health security.Therefore,we should pay more attention to the immunosuppressive population.This paper will briefly analyze the correlation between immunosuppressive population and SARS-CoV-2 variation in the form of review.